Animal Diseases Final Exam Study Guide PDF

1 I. Immunology and Immunodiagnostic Methods A. Barriers to Infection 1. Step 1: block the infection a) Types of blockages/barriers to infection (1) Antimicrobial chemicals in tears (2) Normal microfl...

1 I. Immunology and Immunodiagnostic Methods A. Barriers to Infection 1. Step 1: block the infection a) Types of blockages/barriers to infection (1) Antimicrobial chemicals in tears (2) Normal microflora in upper respiratory and digestive tracts (3) Mucus in the respiratory tract and lungs (4) Urinary flow (5) Skin (6) Stomach acid b) If this step is unsuccessful→infection enters and causes infection c) Proceed to Step 2 2. Step 2: Destroy invaders a) Types of immunity (1) Innate (a) 1st line of defense (b) Main action: phagocytosis (c) Act from the start of an infection but do not adapt to pathogens (d) Recognize patterns (amino acids, proteins, etc. on pathogen surface) (2) Adaptive (a) Response of an antigen-specific B or T lymphocytes to an antigen (b) Immunological memory 3. Common Immunology terms a) Antigen (1) Anything that triggers an immune response (2) Binds to immunoglobulin or T cell receptor b) Pathogen (1) Microorganism that causes disease c) Immunoglobulin (1) Antigen-binding protein made by B cells d) Antibody (1) Secreted immunoglobulin e) Vaccination (1) Deliberate induction of protective immunity to a pathogen (2) On purpose!!!  2 f) Immunization (1) The natural ability to resist infection (2) Happens by random exposure/by chance B. Components of the Innate Immune System 1. Phagocytic cells a) All cells in innate immune response have phagocytic ability (1) Dendritic cells (2) Neutrophils (3) Macrophages 2. Complement Proteins 3. Native defense cytokines 4. Natural killer (NK) cells 5. Antimicrobial peptides 6. All combined = INFLAMMATION a) Multi-step physiological process that aids innate immune system (1) Can be localized or systemic (a) Systemic can lead to sepsis 7. Leukocytes→ nucleated WBCs a) Lymphocytes→specialized leukocytes (1) Adaptive immune response ONLY!! (2) Originates in bone marrow (3) Matures in primary lymphoid organs (a) Bone marrow= B cell (b) Thymus= T cell C. Components of Blood 1. Serum: cell-free liquid, no clotting factors 2. Plasma: cell-free liquid, clotting factors present (1) Use anticoagulant to prevent clotting (2) 92% water by weight (3) Rest is proteins and other solutes b) Erythrocytes→RBCs c) Buffy coat (1) Platelets (2) Leukocytes (a) Neutrophils (i) Take up neutral dyes (b) Eosinophils (i) Pick up pink dye (c) Basophils (d) Lymphocytes  3 (e) Monocytes d) Lymphatic system (1) Separated circulatory system that drains lymph fluid from extravascular tissue (2) Leukocytes enter lymphatic system through capillary beds→lymph nodes (a) Gland like structures filled w/ lymphocytes (b) Behave as “checkpoints” (c) When lymphatic fluid w/ pathogens flow through lymph nodes, pathogen is detected→immune response triggered (d) Contains high concentration of lymphocytes and phagocytes e) Immune response cells (1) Myeloid cells→ from myeloid precursor cells→from bone marrow stem cells (2) Divided into 2 categories: (a) APCs (i) Engulf, process, and present antibodies to lymphocytes (ii) Monocytes, macrophages, dendritic cells (b) Granulocytes (i) Contain toxins or enzymes that are released to kill targeted cells (ii) Neutrophils, basophils, eosinophils (3) Immune cell flow chart 3. Phagocytosis a) Mediated by phagocytes (1) Recognize pathogens by using pattern recognition receptors (PRRs)  4 (a) Phagocyte proteins that recognize pathogen-associated molecular patterns (PAMPs) b) Phagocytes engulf and destroy pathogens (1) Use lysosomes (2) Move by amoeboid action c) Types of phagocytes (1) Neutrophils: actively mobile granulocytes (a) Found in blood circulation (2) Monocytes: precursors of macrophages (a) Large cells found in lymph nodes and in the spleen (b) Localized to specific tissues (3) Dendritic cells: use antigen presentation (a) After ingesting antigen, they move to lymph nodes and present antigen to T cells (b) Can be found in blood circulation and can be found in specific tissues d) Steps in phagocytosis (1) Pathogen is engulfed (2) Pathogen is digested into small fragments within vesicle (3) Vesicles with digested protein and MHC from golgi fuse (4) Pathogen fragment binds MHC (5) Antigen-MHC complex is transported to the surface and presented e) Phagocytic killing abilities (1) Toxic oxygen - kills ingested bacterial cells by oxidizing key cellular constituents (a) Happens in the phagocytic cell, doesn’t damage it f) Pathogen Evasion Techniques (1) Neutralizing toxic phagocytic products (a) S. aureus and M. tuberculosis (2) Leukocidins - kill phagocytes (a) S. pyogenes and S. aureus (3) Phagocytosis-resistant capsule (a) S. pneumoniae 4. Complement Proteins a) Important for innate and adaptive immunity  5 b) Causes lysis of pathogens or marks them for phagocytosis c) Lyses many gram negative bacteria d) MAC (membrane attack components) - insert in membrane to form a pore e) Complement activation - achieved by the mannose-binding lectin pathway and alternative pathway (1) Enhances phagocytosis through binding an antibody or complement - OPSONIZATION 5. Inflammation a) Nonspecific Reaction to noxious stimuli b) Symptoms (1) Redness (2) Swelling (3) Pain (4) Heat localized at infection site c) Molecular mediators - chemokines and cytokines d) Effective inflammation - isolates and limits tissue damage, destroys damaged cells and pathogens e) Widespread inflammation - fails to localize pathogen = SEPTIC SHOCK (1) Very deadly condition f) Steps (1) Neutrophils first to arrive at infection site (a) Attracted by interleukins (2) Neutrophils release chemokines to attract macrophages via chemokine gradient (a)DIAPEDESIS : movement of leukocytes via blood vessels to sites of inflammation (i) Phagocyte rolls along blood vessel lining and sticks to endothelial cell (margination) (ii) Phagocyte emigrates to infection site (3) Outcome: rapid localization and destruction of pathogen g) Cytokines (1) Accomplishes intracellular communication in the immune system (2) Regulate cell function and activate various cell types (3) Produced by lymphocytes that are called lymphokines/interleukins h) Chemokines  6 (1) Function as chemoattractants for phagocytes and lymphocytes (2) Produced by lymphocytes and other cells in response to pathogens i) Fever response (1) Phagocyte engulfs pathogen (2) Pyrogens are released as pathogen is digested and stimulate pyrogenic cytokine release (3) Interleukin-1 travels through the bloodstream to the hypothalamus and triggers prostaglandin release (4) Prostaglandin resets body temperature by raising the set point = FEVER 6. Natural Killer cells a) Different from T and B cells (1) Destroy cancer cells and cells w/ intracellular pathogens via granzymes and perforin (2) Kills in the absence of MHC 1 (3) Immune cells all have MHC 1 and 2 (4) Others only have MHC 1 (5) Prior exposure not required (6) Not enhanced and does not exhibit memory w/ target cells (7) Steps (a) Diseases cell has no MHC 1 and has stress protein on cell membrane (b) NK MHC 1 receptor has nothing to bind to, stress protein receptor binds to stress proteins (c) Granules w/ perforins and granzymes enter diseased cell (d) Cell death via apoptosis is induced 7. Components of Adaptive immunity a) Acquired ability to recognize and destroy a specific pathogen b) Depends on prior exposure c) Uses T and B cells d) T cells make T cell receptors e) B cells make antibodies/ immunoglobulins 8. Three rules of adaptive immunity a) Specificity: immune cells recognize and react w/ individual antigens via direct molecular interactions b) Memory: immune response to a certain antigen is faster and stronger bc of prior exposure  7 (1) Prior exposure results in multiple copies of antigen-reactive cells c) Tolerance:immune cells don’t react to self antigen (1) Self-reactive cells are destroyed during development 9. Types of T lymphocytes a) T-cytotoxic cells (1) Recognizes antigen presented by MHC 1 protein on infected cell (2) Kills antigen bearing target cells directly b) T-helper cells (1) Interact w/ peptide MHC 2 complexes on antigen-presenting cells (2) Act through cytokines to promote immune reactions (3) Two types (a) TH1: start inflammation and immunity by activating macrophages (b) TH2: stimulate antigen-reactive B cells to produce antibodies 10. Interaction of T and B cells, clonal selection a) TH1 -B cell interaction and inflammatory response (1) antigen-presenting phagocyte binds MHC 2 receptors to TH1 TCR (2) TH1 releases cytokines that stimulate inflammation b) TC-B cell interaction (1) antigen-presenting phagocyte binds MHC 1 receptors to TC TCR (2) TC releases perforins and granzymes= target cell lysis c) Antibody-mediated immunity (1) Happens right after first antigen exposure= PRIMARY IMMUNE RESPONSE (a) B cell presents antigen (b) TH2 TCR binds to MHC2-antigen complex = triggers cytokine release (c) Cytokines activate B cell to transform it into a plasma cell (i) Expanded cytoplasm (ii) ER has high protein synthesis= high immunoglobulin synthesis (d) Plasma cell produces more antibodies d) Clonal selection (1) Starts w/ activated T helper 2 cell  8 (2) Activated B cells (lymph node or spleen) make different versions of antibodies to target one antigen (3) One B cell clone has the most efficient and effective antibody and becomes memory cell (4) Plasma cells secrete large amounts of memory cell antibody 11. Antibody a) Immunoglobulin G (IgG) - most common circulating antibody b) Synthesized form different gene products c) Connected by disulfide bonds d) 4 polypeptide chains - 2 heavy and 2 light chains (1) Antigen-binding site results from interactions between heavy and light chains e) Constant chains - same for every Ig type f) Variable chains - different for every Ig type (1) Shape alters based on antigen g) Enzymes that can break peptide chains (1) Trypsin (2) Ficin (3) Papain h) Immunoglobulin types (1) IgM - Has additional constant heavy chain (a) Usually in aggregate of 5 attached by at least one joining chain (b) First antibody secreted in adaptive immune response (c) Energy expensive and not sustainable long-term (d) Agglutination - cell clumping (2) IgA - present as a dimer (two Igs) (a) Present in body fluids (saliva, tears, breast milk colostrum) (b) First barrier and works w/ innate immune response (c) Protects mucous membranes (d) Also does agglutination (3) IgG - basic Ig structure (a) Found in blood, lymph, breast milk, fetal circulation (b) Most dominant antibody  9 (c) Responsible in neutralization, opsonization, agglutination, newborn immunity (4) IgE (a) Found in serum and binds to eosinophils (b) Present in allergic rxns (5) IgD (a) Found in serum (b) No known function 12. Antibody diversity a) Mechanism is exclusive to T and B cells (1) Somatic recombination - meiosis, gametes (2) Hypermutation - errors, can lead to blood borne cancers (lymphoma, leukemia) (3) Gene rearrangement - dependent on antigen (a) Kappa chain gene rearrangement 13. Modes of Actions for antibodies a) Opsonization (1) Result: antigen destruction (a) Pathogen is marked with antibodies for phagocytic cell to recognize (b) Antibody markers bind to phagocytic cell receptors (c) Ingestion of pathogen begins and pathogen is destroyed in vesicle b) Neutralization (1) Stops toxin before it reaches cell (2) Toxin binds to antitoxin = neutralizes toxin so it can’t damage cell c) Agglutination (1) Antibody marks viral pathogen by binding to viral envelope protein (2) Blocks binding of viral pathogen to host cell= viral particle neutralized (3) Multiple antibody-pathogen complexes clump together 14. Monoclonal vs. Polyclonal Antibodies a) polyclonal : antibodies made by many different B cell clones (1) naturally occurring; cannot be made in vitro (2) Provide adequate immune protection, but not reproducible b) Monoclonal : antibody made by a single B cell clone  10 (1) Produced in a lab/in-vitro via hybridoma technique c) Hybridoma technique (1) Uses myeloma cells (cancerous and immortalized (2) Fuse w/ B cells isolated from spleen to make hybridomas (3) Grow hybridomas in cell culture and clone individual hybridomas (4) Perpetuate one clone to make monoclonal antibodies 15. Antigen-antibody reactions utilized in laboratory testing and diagnosis a) In Vitro antigen-antibody reaction : serology (1) Study of antigen-antibody interactions in vitro (2) Usefulness of test is based on: (a) Specificity: ability of an antibody preparation to recognize a single antigen (b) Sensitivity (i) Lowest amount of an antigen that can be detected (c) Precipitation: antigen-antibody reaction between soluble antibody and antigen results in insoluble complex (i) Ex: Agar Gel Immunodiffusion (AGID) (d) Neutralization:: antibody blocks or distorts antigen to reduce or eliminate its activity (i) In vitro or in vivo (e) Agglutination: antigen clumps when mixed with its specific antigen (i) More sensitive than precipitation tests (ii) Direct agglutination: Identifies blood type (a) Type O - no agglutination w/ Ab A or B (b) Type A - agglutination w/ only Ab A (c) Type B agglutination w/ only Ab B (d) Type AB - agglutination w/ Ab A and B (iii) Latex bead agglutination - s. Aureus (f) Immunofluorescence  11 (i) Antibodies are modified w/ UV dyes to help detect antigens (ii) Common dyes - rhodamine B (red) fluorescein isothiocyanate (yellow-green) (iii) Methods (a) Direct method - antibody of a specific antigen is covalently linked to fluorescent dye (b) Indirect method - non fluorescent antibody is detected by a fluorescent antibody that targets the non fluorescent one (iv) Antigen present= pathogen cells fluoresce (v) Applied directly to host tissue - fast diagnosis (vi) Can be used on malignant cells (vii) Can be used to separate mixtures into pure cultures (viii) Can be used to define # of individual cell type in a mixture (flow cytometry) b) Enzyme Immunoassay, Enzyme-linked immunosorbent assay and Radioimmunoassay (1) Very sensitive (2) EIA - uses enzymes to label antibody molecules (a) Ex: covid, flu, pregnancy, drug tests (i) Direct EIA - detects antigen (ii) Indirect EIA - detects antibody (iii) Competitive EIA - detects antigen (a) Color product inverse to amount of antigen in sample (b) Known antigen-antibody amount is mixed w/ patient sample (b) Results - colored product (i) Amount of colored product=amount of antigen present (3) RIA - radioisotopes label antibodies (a) Uses isotope iodine-125 as conjugate (b) Used to measure rare serum proteins  12 (i) HGH, glucagon, vasopressin/ ADH, testosterone, insulin (ii) Illegal drug tests c) Immunoblot/ Western blots (1) Electrophoresis of proteins, followed by transfer to a membrane and detection by adding specific antibodies (2) Can detect antibodies of antigens or antigens themselves II. Prions and Transmissable Spongiform Encephalopathies A. Prions 1. Smaller than smallest known virus 2. Proteinaceous infectious particle 3. Found naturally in the body and start off as normal proteins 4. Normal protein vs. Prion a) Normal proteins : glycoprotein normally at cell surface and inserted in the plasma membrane (1) Secondary structure w/ alpha helices (2) Easily soluble (3) Easily digested by proteases (4) Encoded by PRNP gene (humans) on chr. 20 b) Prion/ Abnormal protein: same amino acid sequence and primary structure as normal protein (1) Secondary structure w/ beta helices (2) Converts normal protein to abnormal protein when they come in contact (3) Insoluble in everything but the strongest solvents (4) Highly resistant to protease digestion (a) Survives post-mortem (5) Extremely resistant to heat, normal sterilization, sunlight (6) Doesn’t trigger immune response 5. Different than protists a) Protists - group of eukaryotic microorganisms and can be unicellular or multicellular b) Prions - not alive! Just simple misfolded proteins B. Bovine Spongiform Encephalopathy/Mad Cow Disease 1. Atypical BSE prions a) H-type: high molecular mass fragments b) L-type/ bovine amyloidotic spongiform encephalopathy (BASE): lower molecular mass fragments  13 2. Animal Transmission a) Feed contaminated w/ scrapie or unknown BSE b) Maternal transmission (1) Low risk 3. Human Transmission a) Consuming infected cattle products can lead to vCJD b) Genetic susceptibility 4. Clinical Signs a) 2-8 years incubation period b) Neurological signs (1) Apprehension (2) Fear (3) Easily startled (4) Depression c) Final stages (1) Excitable (2) Hyperreflexia (3) Hypermetria (4) Ataxia (5) Muscle fasciculation (6) Tremors d) Terminal stage (1) Decreased rumination (2) Loss of body weight and condition 5. Treatment a) No known treatment for BSE b) Affected herds: 2-3% morbidity, 100% mortality 6. Diagnosis a) Slowly progressive, fatal neurologic disease b) Differential diagnoses:identifying and distinguishing between two or more conditions, diseases, or disorders that share similar symptoms or clinical features. (1) Rabies (2) Brain tumor (3) Lead poisoning (4) Spinal cord trauma c) No ante-mortem testing d) Post-mortem sampling of brain, medulla, spinal cord, and brain stem (1) Spongiform changes in gray matter (2) Detection of abnormal prion protein w/ antibodies  14 (3) Immunohistochemistry - gold standard (4) Western blotting, ELISA 7. Prevention a) Infected food animals cannot enter food supply b) Advanced Meat Recovery (AMR) (1) Prohibition of spinal cord tissue, dorsal root ganglia, and skull (2) Routine testing for BSE c) Prohibition of air-injection stunning of cattle at slaughter (1) Air injection causes brain particles to become airborne (2) Infected BSE brain particles can spread to food products C. Variant Creutzfeldt-Jakob disease (vCJD) 1. Types of CJD a) Familial/ Genetic: caused by an inherited mutation in the prion protein gene, PRNP (1) A child must have one copy of the gene to develop the disease (2) 10-15% of cases b) Sporadic/Spontaneous: caused by random and unknown protein misfolding (1) 85% of cases c) Iatrogenic: caused by medical procedures like organ or tissue transplants, blood transfusions, or exposure to contaminated surgical instruments or pituitary hormones (1) Less than 1% of cases d) vCJD: caused by humans consuming cattle products infected w/ BSE (1) All humans have genetic susceptibility (a) Codon 129 of PrPc 2. vCJD vs. CJD a) vCJD (1) Average onset age: 26.3 yrs (2) Illness duration: 14.1 months (3) Transmission: eating BSE products b) Classic CJD (1) Average onset age: 65 yrs (2) Illness duration: 4.5 months (3) Transmission: sporadic 3. Clinical symptoms  15 a) Initial symptoms (1) Depression (2) Schizophrenia- like psychosis (3) Unsteadiness (4) Walking difficulty (5) Involuntary muscle movement b) Progresses to patient becoming completely immobile and mute 4. Diagnosis a) Antemortem diagnosis (1) Neuropsychiatric disorder longer than 6 months (2) Abnormal EEG (3) Tonsillar biopsy of prion protein b) Postmortem diagnosis (1) Amyloid plaques surrounded by vacuoles (2) Prion protein accumulation in cerebellum (3) Spongiform appearance in gray matter 5. Treatment a) No effective treatment available, but some drugs are being experimented b) Symptomatic treatment c) Supportive care III. Canine and Feline Viral Diseases A. Rhabdovirus = Rabies 1. Replication a) Enveloped negative ssRNA virus b) Bullet shaped c) Transcription takes place in cytoplasm (1) Transcription of - strand mRNA by viral RNA polymerase→ + strand mRNA (2) Translation via host enzymes into more viral RNA polymerase and proteins (3) Viral RNA polymerase converts + strand mRNA→ - strand mRNA (4) Proteins and - strand mRNA assemble to form new virus 2. Pathogenesis a) Transmission: Reservoir species (1) In N. America - reservoir species are wildlife (a) Skunks, raccoons, coyotes, bats, foxes (i) Raccoons for NE USA  16 (2) No cat-cat transmission reported (3) Feline are more susceptible to rabies since 1987 (a) Dogs are more policed for rabies than cats (i) Vaccinations + dog registration b) Direct transmission - virus laden saliva introduced to live tissue, usually via bite wound (1) Saliva glands innervated by parasympathetic nerves (2) Rabies causes more salivation c) Can be inhaled or ingested, but less likely d) Incubation period: 21-80 days (1) Both prolonged and variable w/ no clinical signs e) Virus replicates in muscle cells near bite wound and travel up motor neurons to peripheral nerves to salivary glands (1) In humans, they would be in a coma at this point 3. Clinical Signs/Symptoms a) CNS disturbance b) Behavior changes and unexplained paralysis c) Anorexia d) Apprehension e) Ataxia f) Altered phonation g) Temperament changes 4. Disease Progression a) Patient has to be quarantine to limit nosocomial exposure b) Prodromal stage (1) 1-3 days (2) Vague CNS signs c) Excitative stage (1) “Mad dog syndrome” (a) Aggression (b) Apprehensive (c) Temper changes (2) Irrational, easily provoked (3) Patient not technically conscious d) Paralytic stage (1) Paralysis of throat and masseter muscles = lockjaw (2) Inability swallow (3) Paralysis spreads throughout body = eventual death 5. Diagnosis a) Immunofluorescence microscopy on fresh brain tissue b) Whole brain must be submitted  17 c) Mouse inoculation text - backup B. Rabies Vaccination Protocols 1. Vaccine recommended for all high-risk personnel a) Vets b) Animal control c) Lab personnel 2. Vaccine is not enough if you actually get exposed or bit 3. Immunization requires vaccine + IgG antibody post-exposure (PASSIVE IMMUNITY) a) IgG that is not made in body allows for temporary neutralization of virus b) Only lasts ~ 2 weeks 4. Prevention/Control a) Notify of suspected cases b) Euthanize dogs w/ clinical signs or that have been bitten by a rabid animal c) Leash laws d) Vaccinate young dogs e) Stray dog control f) Register dogs C. Canine Parvovirus 1. Parvovirus - Nonenveloped + ssDNA virus 2. Replication a) Replicates in the nucleus bc they can use the host cell’s DNA polymerase b) Very unstable = more prone to mutation and evolution= new strains form 3. CPV-2 a) Enteric pathogen in dogs b) CPV-1=FPLV(feline panleukopenia virus) but not CPV-2 c) Three antigenic variants (1) CPV-2a (2) CPV-2b (3) CPV-2c d) High genetic substitution rate= random and quick mutation (1) Different strains were identified via Western blots that looked for specific proteins on the parvovirus (2) PCT didn’t exist yet at this point e) Very stable in environment (1) Withstands variable temp and pH (2) Can survive for months in areas  18 (3) Resistant to common disinfectants f) High risk to rottweilers, american pit bull, german shepherds, and dobermans g) Low risk to toy poodles and cocker spaniels h) 90% morbidity, 16-35% mortality 4. Transmission a) Direct contact w/ infected dog’s body fluids (1) Vomit (2) Diarrhea b) Indirect contact w/ contaminated fomites of fecal matter and vomit c) Viral sheds in feces 3 weeks after recovery (1) Recovered dogs can be carriers and shed virus 5. Pathogenesis a) Post ingestion - viral replication in lymphoid tissue of the oropharynx b) Spreads into bloodstream and attacks rapidly dividing cells (1) In bone marrow and lymph nodes = lymphocytopenia and neutropenia (2) In jejunum and ileum = bloody diarrhea, vomiting, viremia c) Incubation: 3-8 days 6. Symptoms/Clinical Signs a) Asymptomatic but symptoms can be triggered by stress b) Myocarditis - inflammation of the heart's middle muscle layer (1) Used to be a problem for neonatal pups (2) Chest pain (3) Shortness of breath (4) Fatigue (5) Arrhythmia c) Gastroenteritis - inflammation of the stomach and intestines (1) 6-20 week old pups (2) Lethargy, vomiting, diarrhea, anorexia, fever, salivation 7. Diagnosis a) Positive fecal ELISA test b) Hemagglutination test c) Viral titers 8. Treatment a) Supportive care  19 (1) Fluids (2) Vomit control (3) Electrolyte balance (4) No food or water until vomit is under control (5) Bland diet (6) Glucose, B vitamins 9. Prevention/Control a) Clean contaminated areas (1:30 bleach) b) Isolate puppies and adult dogs c) Vaccination D. Feline Panleukopenia/ Feline Distemper (FPLV) 1. Etiology a) Retrovirus - FELV-A,b, and C b) Disease incidence related directly to population density c) Healthy cats w/ infection - reservoirs 2. Transmission a) Direct/ Indirect contact w/ body fluids (saliva, tears, urine, feces) b) Vertical transmission (in utero, milk) 3. Pathogenesis a) Oronasal inoculation = auto-infection b) Virus replicates in lymphoid tissue c) Spreads to blood mononuclear cells (macrophages) and eventually full body (1) Viremia evident 2-4 weeks after infection 4. Disorders caused by FELV a) Immunosuppression b) Lymphoid or myeloid tumors c) Anemia d) Immune complexes e) Reproductive problems f) Enteritis g) Neuropathy 5. Treatment a) Hard to treat and get rid of retroviruses (1) Retroviruses - use integrase to integrate into host genome=persistent viral infection b) Treat the disorders caused by FELV (1) Antiviral drugs (2) Interferon (3) Immunostimulants  20 6. Prevention/Control a) Test + remove all cats in a cattery situation (1) Lift quarantine 2 consecutive tests 12 weeks apart b) Test all cats coming into cattery c) Breed only FELV negative cats d) Vaccinate only afebrile cats 7. Feline Panleukopenia Virus and HIV a) Both are retroviruses (1) Replicate by using reverse transcriptase (a) RNA→DNA intermediate b) Both target immune cells (1) HIV = CD4+ cells (a) T-helper cells and macrophages (2) FPLV= blood mononuclear cells (a) Macrophages c) Both lead to immunosuppression and opportunistic infections d) Both lead to cancers (1) HIV=kaposi’s sarcoma (2) FPLV= lymphoid and myeloid tumors e) Both persistent viruses (1) Use integrase to integrate into host genome for continuous replication IV. Diseases Caused By Eukaryotes (Protozoans, Fungi, Screwworm Myiasis) A. What is a eukaryote? 1. Characteristics a) Nucleus containing DNA and enclosed w/ nuclear membrane b) Multiple chromosomes c) Linear genome d) Can be haploid or diploid e) Histones f) Use mitosis and meiosis g) Membrane bound organelles 2. Organisms a) Protozoans/ Protists - unicellular, mostly free-living b) Fungi c) Helminths - worms d) Ectoparasites - larval forms of insects B. Toxoplasmosis 1. Protozoan parasite - Toxoplasma gondii 2. Most prevalent parasitic infection (1-2 billion people worldwide)  21 3. Classification a) Domain: Eukarya b) Kingdom: Protozoan c) Clade: Alveolate d) Phylum: Apicomplexa e) Genus: Toxoplasma 4. Intestinal protozoan a) Entire life cycle takes place in intestinal microvilli 5. Definitive host: felines 6. Humans: dead end hosts 7. Direct Transmission: ingesting oocysts or pseudocysts a) Humans - handling cat litter or ingesting contaminated, undercooked meat b) Mild infection for immunocompetent and non-pregnant mothers 8. Vertical transmission: can be transmitted to fetus in first trimester from non-symptomatic effects on baby a) T in TORCH infections - vertically transmitted diseases that cause severe baby complications (1) T- toxoplasmosis (2) O - Other (HIV, syphilis, zika virus) (3) R- Rubella (4) C-Cytomegalovirus (CMV) (5) H- Herpes Simplex Virus b) Only affects the baby is the mother is actively pregnant when contracting toxoplasma gondii c) Severe effects on baby (1) Cerebritis - cerebral atrophy and intracranial calcifications (2) Chronic placental inflammation - leads to placental insufficiency (3) Low birth weight and premature birth 9. No effective vaccine/treatment for humans or cats C. Cryptosporidiosis 1. Classification a) Domain: Eukarya b) Kingdom: Protozoa c) Clade: Alveolate d) Phylum: Apicomplexa e) Genus: Cryptosporidium 2. Caused by Cryptosporidium parvum - intestinal protozoan  22 3. Transmission: fecal contaminated water a) Highly resistant to chlorination and UV radiation due to thick walled oocyst formation (1) Chlorination - used to kill aquatic bacteria 4. Sedimentation and Filtration are most effective at removing it from water 5. Mild diarrhea that resolves itself in immunocompetent patients 6. Immunocompromised patients - opportunistic infection if infected w/ HIV a) Constant gastroenteritis flare-ups b) Life threatening malabsorption D. Fungi 1. Mostly multicellular and form a network of hyphae 2. Conidia: Hyphae that extend above the surface and produce asexual spores a) Pigmented and resistant to drying b) Spores need a warm and wet environment in order to propage (1) Dry, cold environment = spores present, but won’t make hyphae 3. Mycelia: compact tufts of hyphae 4. Chitin: make up fungal cell walls 5. Fruiting bodies: macroscopic reproductive structures a) Ex: mushrooms 6. Can cause disease in plants and animals a) Geomyces - white nose syndrome in bats b) Mycoses - athlete’s foot (cutaneous) and histoplasmosis (pulmonary/systemic) (1) Cutaneous - on the surface of the body (2) Systemic - fungus breaks blood barrier and affects organs (a) Harder to treat than cutaneous fungal infections E. Coccidioides Immitis 1. rare , systemic, fungal infection 2. Lives on dead matter 3. Soil - reservoir a) Outbreaks correspond to environmental disturbances that kick up soil (ex: earthquakes, dust storms, construction sites, archaeological digs) 4. Dimorphic fungus  23 a) Ascomycete b) Two life cycle phases (1) Saprophytic phase (a) Endospore turns into tubular structure (b) Tubular structure turns into mycelia (c) Mycelia turns into arthroconidia in soil (d) Arthroconidia become airborne and are inhaled by humans or animals (2) Parasitic phase (a) Arthroconidia turns into spherule in the lungs (b) Mature spherule releases endospores (c) Endospore cycle continues in the body or endospores are coughed out into the environment 5. Pathology a) Looks like a tumor or tuberculosis (differential diagnosis) b) 60% of cases - asymptomatic (1) Identified w/ positive skin test c) 40% of cases - mild to severe infection (1) Pulmonary - infected cough up blood (2) Immunocompromised people - highly susceptible to serious infection (a) 1987 - CDC adds C. immitis to list of HIV-associated diseases 6. Diagnosis a) Clinical signs in endemic areas b) Laboratory testing (1) Spores found in exudates (2) Serology - complement-fixing antibody tests (a) IgG anti coccidioidal antibodies (b) Titer more than 1:4 = current or recent infection (c) Titer more than 1:32 = increased risk of spreading throughout the body c) Spherules visualized in sputum, pleural fluid, cerebrospinal fluid, or exudates from draining lesions 7. Treatment a) Disseminated infections (1) Long term therapy for at least a year (2) Antifungal agents (3) Guarded prognosis  24 b) Primary form of infection: good prognosis F. Screwworm Myiasis 1. Maggot infestation of bot fly larvae that affect muscle tissue 2. Sterile male technique - developed 1958 a) Screwworm flies mate once a lifetime and die b) Irradiating one of the flies in a pair sterilizes them = no reproduction 3. Animal Transmission a) Female fly deposits egg in live tissue wound b) Larvae feed on living tissue c) Non-contagious d) Common for multiple infestations in one wound 4. Human Transmission - same as animals a) Can transmit adult screwworms 5. Clinical Signs in Animals a) Larvae visible in wound by 3 dyas b) Bloody discharge c) Foul-smelling odor d) Depression e) Off feed f) Separation g) Attempt to control discomfort 6. Clinical signs in Humans a) Larvae visible within wound b) Bloody discharge c) Foul-smelling d) General discomfort 7. Diagnosis a) Microscopic examination for larvae identification b) Sample collection and handling (70% alcohol) c) ELISA tests in development 8. Treatment a) Topical application of larvicide for 2-3 days b) Spray or dip wound with organophosphate (1) Cannot put animal in food cycle (2) Prevents reinfestation V. Helminthic Infections A. Helminths 1. Worms 2. Bilateral symmetry, head and tail, tissue differentiation  25 3. Usually have digestive, circulatory, nervous, excretory, and reproductive systems 4. Parasitic helminths a) Spend most or all of their lives in the host b) Specializations (1) Lack of digestive system and absorbs nutrients from host’s food, body fluids, or tissues (2) Reduced nervous systems (3) Reduced or absent means of locomotion (4) Complex reproductive system - many eggs that can infect another host B. C. elegans 1. Common roundworm 2. Model organism - used to research other helminths 3. Only non-parasitic helminth C. Phyla of Helminths 1. Platyhelminthes (flatworms) a) trematodes/flukes b) cestodes/tapeworms 2. Nematodes - roundworms D. Schistosomiasis 1. Caused by schistosoma species/ blood flukes 2. Causes damage to blood vessels, liver, and other organs 3. Live in fecally contaminated water a) Reason why it’s so rare in US - we have a really good water sanitation system here 4. Burrow through skin and enters the circulatory system 5. Dioecious - male and female are different organisms and have different characteristics 6. Life cycle a) Egg hatches in water b) Larva - free swimming and infects aquatic snail c) Asexual reproduction takes place in the snail d) Larva leave snail and are free swimming in water e) Larva penetrate human skin coming in contact in water f) Larva mature into adult flukes in blood vessels of intestine g) Sexual reproduction occurs h) Fertilized eggs pass in feces E. Asian Liver Fluke 1. Clonorchis sinensis - trematode 2. Infests gallbladder, bile ducts, pancreatic ducts  26 a) Causes biliary cirrhosis and jaundice 3. No transmission in US because intermediate hosts aren’t available here 4. Intermediate host - snail F. Lung Fluke 1. Paragonimus westermani a) Lives in bronchioles of humans and other animals b) Transmission - eating undercooked crayfish G. Rat LungWorm 1. Causes meningitis 2. intermediate host - giant african land snail a) Invasive in Florida!! 3. Introduction of intermediate host allows humans to get rat lungworm in a region where it is not common H. Tapeworms/Cestodes 1. Characteristics a) Long flat bodies b) Intestinal parasites c) Lack a digestive system, absorb food through cuticle d) Scolex - head of worm (1) Has suckers for attachment e) Proglottids - segments of the body of the worm (1) Monoecious - proglottids have both male and female reproductive organs (2) Farthest from the head - mature and contain fertilized eggs 2. Beef tapeworm a) Caused by taenia saginata b) DH - humans c) IH - cattle d) Infection occurs by ingestion of contaminated, undercooked beef (measly beef) 3. Pork tapeworm a) Caused by taenia solium b) DH - humans c) IH - pigs d) Infection occurs by eating undercooked contaminated pork or human-human contact e) Also causes cysticercosis - tapeworm eggs encyst in the brain 4. Echinococcus granulosus a) DH - dogs and coyotes  27 b) Humans - accidental intermediate host (1) Come into contact w/ dog feces or saliva c) Causes cystic hydatid disease I. Nematodes/Roundworms 1. Characteristics a) Cylindrical body tapered at end end b) Complete digestive system - mouth, intestine, anus c) Covered w/ tough cuticle - resists drying and crushing d) Dioecious - separate males and females e) Infections caused by eggs or larvae 2. Ascariasis a) Ascaris lumbricoides b) Most prevalent helminth infection worldwide c) Life cycle (1) Unembryonated eggs in feces (2) Eggs embryonate: L2 inside egg (3) Egg ingested during L2 (transmission stage) (4) Egg hatches in Small Intestine, molts twice: L3 → L4 (5) L4 enters circulation and migrates to lungs (6) L4 coughed up and swallowed, molts into adult in SMALL INTESTINE d) Pathology (1) Migration: some L4 get lost and die - may cause inflammation/granuloma (spleen, liver, brain) (2) Pulmonary damage: damage to lung capillaries - blood pools and leaks - (3) lung congestion → bacterial infection (Loeffler's syndrome - increased eosinophils in lungs in response to surface proteins (4) Intestinal pain, allergic reactions to waste, obstruction, peritonitis e) Pinworms (1) Enterobius vermicularis (2) Spends entire life in human host, adults live in large intestine (3) Itching of perianal or genital region - females lay eggs there f) Hookworms (1) Necator americanus, ancylostoma duodenale - passage through skin (2) Cause iron deficiency anemia through chronic GI blood loss g) Heartworm (1) Dirofilaria immitis (2) DH = dogs  28 (3) Humans = accidental IH (a) Larva can’t mature in humans (b) Larva die and immune system reacts to dead larva - inflammation - pulmonary dirofilariasis (4) Life cycle (a) Mosquito takes a blood meal (L3 enters bite wound) (b) Adults in pulmonary arteries and heart (c) Adults produce microfilariae that are found in peripheral blood (d) Mosquito takes a blood meal (ingests MF) (e) MF penetrates mosquitos midgut and migrate to malpighian tubules (f) Molts L1 → L3 (g) Migrate to head and proboscis J. Pathophysiological effects of helminth infections 1. Mechanical obstruction - worms block or displace organs/tissues a) intestinal, lymphatic, displacement of normal tissues b) Examples: ascariasis, lymphatic filariasis, hydatid disease (echinococcosis), cysticercosis (t. solium) 2. Facilitating bacterial invasion - create conditions or providing mechanisms that allow bacteria to easily enter and establish themselves within a host organism a) Strongyloidiasis, filariasis 3. Anemia - loss of blood or vitamin B12 (pernicious anemia) a) hookworms , fish tapeworms 4. Chronic inflammation - long term immune response to parasite presence in the body a) Onchocerciasis VI. Pharmacology and Vaccines A. Antimicrobial agents 1. Physical antimicrobial control a) Heat sterilization b) Radiation sterilization c) Filter sterilization - expensive! (1) Important for waterborne protozoan infections because cysts are resistant to chlorine 2. Chemical antimicrobial control - two categories a) Used to control microorganisms in commercial and industrial applications (1) Chemicals in foods, AC cooling towers, textile and paper products, fuel tanks b) Prevent human pathogen growth in inanimate environments and on external body surfaces (1) Sterilants - kills 99.99% of microbes (2) Disinfectants - kills most pathogenic organisms on inanimate surfaces  29 (3) Sanitizers - reduce microbial population on a surface to safe levels according to public health standards (4) Antiseptics - inhibit or kill microorganisms on living tissue 3. In Vivo antimicrobial agents a) Classified based on mode of action, molecular structure, and antimicrobial spectrum of activity (1) Modes of actions (a) Inhibit DNA gyrase (b) Inhibit cell wall synthesis (c) Inhibit folic acid metabolism (d) Inhibit cytoplasmic membrane structure and function (e) Inhibit lipid biosynthesis (f) Inhibit RNA elongation (g) Inhibit DNA-directed RNA polymerase (h) Inhibit protein synthesis (50S, 30S, and tRNA) (2) Antimicrobial spectrum of activity (a) Eukaryotes - fungi (b) Bacteria - mycobacteria, gram neg, gram pos (c) Obligately parasitic bacteria - chlamydia, rickettsia (d) Viruses - RNA and DNA b) Drug resistance (1) Most drug resistant pathogens are gram negative bacteria (2) Why? (a) Outer Membrane layer w/ LPS makes it harder for drugs to penetrate into the bacteria (3) Examples (a) Streptococcus pneumoniae - pneumonia (i) Gram positive (b) Neisseria gonorrhoeae - gonorrhea (i) Gram negative (c) Salmonella spp - salmonella (i) Gram negative (d) Staphylococcus aureus - staph infection (i) Gram positive (ii) Drug resistant since 1950 B. Types of Immunity 1. Natural active immunity - acquired during an infection that initiates an adaptive immune response 2. Natural passive immunity - antibody transfer across placenta or breast milk 3. Artificial active immunity/Immunization - exposure to a controlled dose of a harmless antigen to induce antibody formation a) Vaccinations involve this type of immunity!!!  30 b) Herd Immunity: 80% of a population is vaccinated in order to effectively eradicate the spread of disease c) Boosters: additional vaccinations that produce a secondary response and higher antibody titer 4. Artificial passive immunity - injection of an antiserum derived from an immune individual a) Ex: IgG therapy in rabies and ebola b) Temporary, lasts up to 3 weeks c) No permanent immunity, no memory produced C. Vaccines 1. Vaccines w/ live cells or viruses are more effective than dead or inactivated material 2. Types of vaccines a) Live attenuated vaccine - pathogen is alive, but severely weakened (1) Used for pathogens that are not as deadly unless in a high enough dose (2) Provide lifelong immunity and both humoral and cell-mediated defense (3) Dangerous for immunocompromised people b) Killed vaccine - pathogen is dead or inactivated (1) Used for extremely viral pathogens that can cause serious disease even in small doses (2) No risk of disease (3) Needs a booster to keep adaptive immunity c) Subunit vaccine - uses specific parts of the pathogen that are nonpathogenic (1) Can contain either a fractionized pathogen or a toxoid (2) Fractionation: the process of breaking down a pathogen and isolating its nonpathogenic parts (3) Toxoid: chemically or thermally inactivated toxins (a) Need boosters (b) Weaker antigen d) DNA vaccine - contains a cloned subunit proteins gene in a DNA vector that stimulates an immune response e) Live vector vaccine - uses a harmless virus to transfer the subunit protein gene of a more virulent pathogen (1) Uses subcloning to transfer genetic material f) Recombinant subunit vaccine - subunits are genetically engineered using recombinant DNA technology (1) Expression: triggers the production of the desired protein or antigen inside the host after the gene has been subcloned into the vector g) Conjugated vaccine - combine a polysaccharide antigen from a pathogen and a protein carrier to enhance the immune response (1) Weak antigen - polysaccharide  31 (2) Strong antigen - protein carrier h) Importance of recombinant and conjugated vaccines (1) Overall safer when dealing with extremely virulent pathogens like ebola (2) Helps us understand transcribing and translating the genome to better understand how the virus works i) Fertilized eggs and vaccines (1) Fertilized eggs: have embryonic stem cells (a) Virus replicates in cells, then are collected and inactivated for a vaccine 3. What’s in a vaccine bottle? a) The actual vaccine b) Adjuvant - immunological agent that increases the immune response to the vaccine (1) Boosts visibility of the immune system (2) Ex: Peanut oil, corn oil c) Preservatives : increase shelf life of vaccine (1) Formaldehyde (2) Gentamycin (3) Thimerosal (a) Faulty study made a link between thimerosal in vaccines and autism (b) Started anti-vaxx beliefs 4. Vaccine administration routes a) SQ - subcutaneous b) IM - intramuscular c) IN - intranasal d) Oral - polio vaccine 5. Response to vaccination a) Maximum immune response - 2 weeks after vaccine is administered b) Boosters stimulate maximum immunity c) Once memory cells are established, annual boosters are recommended 6. Why do vaccines fail? a) Animal is already incubating disease (1) 2 week wait period for maximum response (2) stress=immunosuppression b) Vaccine is ineffective (1) Denatured by heat, UV light, cold chain storage c) Animal state at time of vaccination (1) Pregnant - maternal antibody interference (a) Pregnant animals have depressed T-cell function d) High dose infectious inoculum can overcome immunity VII. Bovine and Equine Diseases A. Bovine Respiratory Disease/Shipping Fever  32 1. Most common disease of feedlot cattle worldwide 2. 75% morbidity, 64% mortality 3. Multifactorial - caused by many factors a) Environmental factors - weaning, transport, co-mingling (1) High pressure water spraying (2) Ventilation (3) Humidity and room temp (4) vitamin/mineral deficiencies (5) Ammonia levels b) Bacterial factors (1) Pasteurella hemolytica - mastitis (2) Opportunistic infections (E. coli, salmonella) (3) Mycoplasma - contagious bovine pleuropneumonia (CBPP) (a) c) Viral factors (1) IBR - infectious bovine rhinotracheitis (a) Found worldwide (b) Disease of all phases of production cycle, beef, and dairy (c) Related to stress and population density (i) Latent infection - activated w/ stress (d) Reservoir - adults (2) BRSV - bovine respiratory syncytial virus (3) PI3 - parainfluenza virus (a) Family: paramyxoviridae (b) RNA virus (c) Symptoms (i) Fever (ii) Nasal discharge (iii) Dry, harsh, tracheal cough (iv) Dyspnea (d) No complications=recovery in 4-7 days (e) Risk for secondary bacterial pneumonia (4) BVD - bovine viral diarrhea 4. Animal transmission a) Introduction of carrier animal to susceptible feedlot herds (1) Most common cause b) Aerosol in close contact c) Direct contact (1) Saliva, urine, fetal membranes, uterine discharge d) Humans - not susceptible 5. Thoughts on the beef and dairy industry a) Stress from Transport: Cattle that are shipped over long distances often experience physical and psychological stress, which weakens their immune systems (1) Stress can result from changes in diet, temperature  33 fluctuations, overcrowding, and lack of rest or water during transport. b) Immune System Suppression: Stress from shipping, along with exposure to new environments and pathogens, can compromise the cattle's immune systems, making them more susceptible to infection c) Poor Conditions: cattle who live in poor conditions can contract shipping fever from environment or pathogens B. Strangles/Equine Distemper 1. Caused by streptococcus equi a) Gram positive, capsulated bacteria b) Survives in environment dependent on temp and humidity for up to 7-9 weeks 2. Highly contagious 3. High morbidity and low mortality 4. Affects horses, donkeys, and mules 5. Transmission: indirect contact w/ fomites and direct contact 6. Shares similar symptoms to influenza a) Differential diagnosis is IMPORTANT 7. Symptoms a) Nasal discharge (green, yellow, or white) b) Fever of 103-107 c) Loss of appetite d) Anorexia e) Depression f) Cough g) Swelling of lymph nodes in the head or neck (1) Filled w/ thick contagious yellow pus (2) Labored breathing due to pressure on the trachea or pharynx h) Difficulty swallowing 8. Distemper vs. Influenza in horses a) Causative agent (1) Bacteria for distemper (2) Virus for influenza b) Same symptoms (1) Distemper has influenza signs but also forms abscesses in the lymph nodes c) Treatment (1) Bacterial infection = antibiotics (2) Viral infection = no antibiotics bc viruses aren’t alive C. Ehrlichiosis/Potomac horse fever 1. Named based on location (potomac river, VA) a) Season based - spring, summer, early fall b) Found around pastures w/ creeks or rivers c) Ill horses are not contagious 2. Unknown transmission - possible ingesting aquatic insects that  34 carry the bacteria 3. Zoonotic = can spread to humans 4. Caused by coccobacilli - neorickettsia risticii a) small , pleomorphic b) Gram negative c) Obligate intracellular pathogen (1) Attacks immune cells (monocytes and granulocytes) 5. In humans - causes human monocytic ehrlichiosis and human granulocytic ehrlichiosis a) Non-specific symptoms (1) Headache, fever, malaise (2) Gastrointestinal signs (3) Rash on trunk, legs, arms, and face b) Severe for immunocompromised people D. Viral Encephalitis/West Nile Virus 1. Big zoonosis in midwestern US 2. Transmission a) Mosquito vector b) Normal host - birds (1) Amplifying host - virus multiples c) Horses and humans = dead-end hosts (1) Virus reaches a cap in replication d) Clinical signs in horses (1) Fever (2) Anorexia (3) Weight loss (4) Depression (5) CNS signs: wide stance, droopy ears, flaccid lips, hanging head (6) Death in 4 days 3. Vaccine available for horses, not humans a) Trivalent formalin - inactivated vaccine E. Vesicular Stomatitis 1. Vesicular = blister, inflammation of skin surface 2. Foot Mouth Disease Virus a) Family:picornaviridae (1) Non enveloped positive ssRNA virus b) Affects cloven-hoofed animals c) Inactivated in extremely acidic or basic conditions (1) pH below 6.5 or above 11 d) Survives in milk, milk products, bone marrow, lymph glands e) Economically devastating 3. Cattle clinical signs a) Oral lesions(vesicles) (1) Epithelium erodes and leads to secondary infections (2) Tongue, dental pad, gums, soft palate, nostrils, muzzle (3) Excess salivation, drooling, nasal discharge  35 b) Lethargy, loss of body condition c) Teat lesions = decreased milk d) Hoof lesions (1) Interdigital space (2) Coronary band - where fur and hoot meet/ nail bed (3) Lameness (4) Reluctant to move e) Necrosis f) Horses not affected g) Sheep and goats = mild signs if any 4. Pig clinical signs a) Hoof lesions (1) More severe than cattle (2) More painful (3) Coronary band, heel, interdigital space b) Lameness c) Snout vesicles d) Oral vesicles 5. Diagnosis a) All vesicular diseases are clinically the same! b) Suspect any animals w/ lameness or excessive salivation and vesicles c) Tranquilization may be necessary d) Lab testing 6. Vesicular Stomatitis Virus a) Family: rhabdoviridae, vesiculovirus b) Mostly in western hemisphere c) Affects horses, cattle, swine, and camelids (1) Sheeps and goats = resistant d) Can affect humans e) Similar to FMD f) 90% morbidity but low mortality g) Transmission (1) Vectors: sandflies, blackflies, seasonal outbreaks (2) Direct: infected animals, contaminated objects h) Clinical signs in horses (1) 3-5 day incubation (2) Fever and vesicles that look like FMD (3) Severely affects horses (4) Oral lesions (5) Coronary band lesions i) Clinical signs in cattle and pigs (1) Vesicles: oral, mammary gland, coronary band, interdigital region (a) Isolate to one area, usually mouth or feet (2) Salivation and lameness (3) Recovery in 2 weeks