Immunology: Innate and Acquired Immunity

• Immunology is defined as the condition of being immune or non-susceptible to the effects of pathogenic substances
• An antigen refers to any substance, like viruses or pollen, that prompts the immune system to produce antibodies.
• Antibodies are proteins produced by B-lymphocytes

Types of Immunity

• Innate immunity is a non-specific immunity present from birth

• It includes physical and chemical barriers like skin, mucous, stomach acid, and respiratory tract cilia

• It is immediate, non-specific, and consistent in strength

• Acquired immunity is the body's specific defense response to an antigen

• It is dependent on antibody production and is very specific

• Repeat antigen exposures lead to a stronger immune response

• Effectiveness is influenced by genetics, health, antigen dose, previous exposures, and innate immunity

• Passive Immunity involves temporary transfer of antibodies from a donor

• Active Immunity follows antigen exposure and results in antibody formation

Types of Antibodies

• IgM is produced during the first exposure to an antigen
• IgG is produced in future immune responses
• IgA provides local immunity, specifically in the GI and respiratory tracts, and conjunctiva
• IgE is linked to parasitic infections and inflammatory reactions
• Too much can cause anaphylactic reactions
• IgD function is somewhat unknown; thought to activate B-cells

Primary vs Secondary Immune Response

• Primary immune response occurs upon first exposure to an antigen, while the secondary response occurs during future exposures
• Primary Response:*
• Slow, taking several days
• Involves IgM antibody production
• Weak, with a low antibody titer
• Antibodies detected for a short time
• More severe disease progression
• Secondary Response:*
• Rapid response, within 1-2 days,
• IgG antibody production
• Strong response with a high antibody titer
• Antibodies are detected for months to years
• Less severe disease progression

Types of Acquired Immunity

• Naturally acquired immunity occurs through natural processes

• Active: antigens enter the body naturally, prompting antibody and lymphocyte production

• Passive: antibodies pass from mother to fetus via placenta, or to infant via mother's milk

• Artificially acquired immunity occurs through artificial means

• Active: vaccination introduces antigens, stimulating antibody and lymphocyte production

• Passive: pre-formed antibodies are introduced via injection of immune serum

Interpreting Titers

• IgM antibodies indicate:
• Recent disease exposure, or initial vaccination
• IgG antibodies indicate:
• A booster vaccination, or past disease exposure/recovery

Vaccine Timing

• Vaccines lose effectiveness if administered while maternal antibodies are present
• Initiating vaccinations after maternal antibodies wane can leave patients vulnerable to natural infection
• Vaccine schedules balance maternal antibody presence and risk of infection

Antibody Transfer to Neonates

• IgG transfer to neonates depends on placental thickness
• 3 membranes: 100% transfer in people and primates
• 4 membranes: majority transferred in cats and dogs
• 5/6 membranes: little to no transfer in ruminants, horses, donkeys, and pigs
• IgA is transferred via colostrum
• A dam's immunity from vaccines passes to offspring and timing of vaccines is paramount

Types of Vaccines

• Modified Live Vaccines (MLV): live, avirulent organisms,
• Provide long-lasting immunity
• Can cause abortions, immunosuppression, and mild symptoms
• Killed Vaccines (KV): contain chemically inactivated organisms
• Safe and stable
• Require repeat doses and may result in a weaker response
• Adjuvants enhance immune response but can cause injection site reactions
• Recombinant Vaccines: produced using DNA technology
• Safe and effective
• Non-adjuvanted to keep reactions down
• Increased cost

Handling and Adverse Reactions

• Vaccines should be refrigerated and reconstituted correctly before administration
• Administration routes = SQ, IM, IN, or transdermal
• Post-vaccine reactions can be minor (local pain, swelling, lethargy, fever) or severe (anaphylaxis)
• Anaphylaxis is immediate hypersensitivity within 20-30 minutes
• Mild Anaphylaxis:*
• Urticaria (hives)
• Facial edema
• Perioccular swelling
• Extremity swelling
• Vomiting and/or diarrhea
• Severe Anaphylaxis:*
• Respiratory arrest
• Cardiovascular collapse
• Death

Immune-Mediated Reactions

• Other Immune-mediated, post vaccine reactions include:
• Immune Mediated Hemolytic Anemia (IMHA): low red blood cells due to lysis
• Immune Mediated Thrombocytopenia (IMTP): low platelet count
• Polyarthritis (inflammation of the joints)

Post-Vaccinal Sarcomas

• Post vaccine sarcomas in cats
• Sarcomas form aggressively and are typically a localized problem, but tendrils spread deep and are difficult to remove

Canine Vaccines

• Core vaccines include rabies, canine distemper, adenovirus, parvovirus, leptospirosis, and +/- parainfluenza
• Noncore vaccines include Bordetella bronchispetica, Lyme disease, Crotalus atrox toxoid, and canine influenza

Feline Vaccines

• Core vaccines include rabies, feline panleukopenia, and feline viral rhinotracheitis/calicivirus (FVRCP)
• FVRCP consists of feline viral rhinotracheitis (herpes), calicivirus, and panleukopenia
• Noncore feline vaccine = Feline leukemia virus (FeLV)

Equine Vaccines

• Equine core vaccines include rabies, tetanus, Eastern/Western equine encephalomyelitis (EEE/WEE), and West Nile Virus (WNV)
• Risk-based equine vaccines = anthrax, botulism, Equine Herpes Virus (EHV), Equine Viral Arteritis (EVA), Equine Influenza, Leptospirosis, Potomac Horse Fever (PHF), Streptococcus equi (Strangles), and Venezuelan Equine Encephalomyelitis (VEE)

Bovine Vaccines

• Examples of bovine vaccines include:
• Bovine Respiratory Syncytial Virus (BRSV)
• Bovine Viral Diarrhea (BVDV)
• Infectious Bovine Rhinotracheitis (IBR)
• Parainfluenza 3 (PI3) Leptospirosis
• Rabies
• Brucellosis
• Clostridial diseases
• Campylobacterosis
• Pasturella, Coronavirus, Rotavirus, E. Coli
• Protocol determined by DVM and Producer to meet the health needs of the herd

Small Ruminant Vaccines

• Small ruminant vaccines = Clostridial diseases (CD-T) and Rabies
• Contagious Echthyma (Sore mouth) vaccine administered by the state veterinarian

Bovine Respiratory Disease Complex

• Bovine Respiratory Disease Complex (BRDC): includes shipping fever
• Shipping Fever: results in upper/lower airway disease (nose, pharynx, trachea, cranioventral lung lobes)
• Symptoms = depression, fever, anorexia, soft cough, abnormal lung sounds
• The causative agents are numerous, and includes viral and/or bacterial infections
• BRDC viral agents: IBR, BRSV, PI-3, BVDV
• BRDC Bacterial agents: Mannheimia haemolytica

Contributing Factors to BRDC

Contributing factors to BRDC:

• Stress before shipping (weaning, surgeries)
• Poor nutrition
• Weather stressors
• Concurrent diseases (parasitism)
• Co-mingling
• Transport
• Lack of food/water
• Processing/handling

Prevention of BRDC

• Management includes:
• Ensure adequate colostrum intake
• Monitor energy/protein of cow prior to calving
• Friendly calving environment
• Substitute colostrum when needed and vaccinate the cow to increase colostral antibodies

Preparing Calves for Shipping

• Condition calves prior to shipping with:
• Vaccinations
• Surgeries
• Weaning more than 3 weeks prior
• Parasite control
• Practicing biosecurity

What to Consider for BRDC Vaccine

• Vaccine considerations: timing, MLV v. Killed, and boosters
• Timing of vaccinations
• Vaccines require time for the immune system to respond
• Modified live vaccines:
• Killed vaccines are safer, but stimulate the immune system less
• MLV vaccines can be used in pregnant/nursing cows, but some cannot
• Follow label recommendations for timing

Leptrospiriosis

• Leptospirosis (“5L): Leptospira spp, aerobic spirochete that live in wet environments
• There are 180 serovars
• Reservoirs = wildlife, rodents, and domestic animals
• Disease presentation in cattle typically shows reproductive issues
• Includes abortions, stillbirths, weak calves, agalactia
• Other symptoms = kidney failure, hemolytic crisis, or liver failure
• Leptrospiriosis is zoonotic!

Significant Serovars of Leptospirosis in Cattle

• Significant Leptospirosis serovars in cattle include:
• L. borgpetersenii serovar Hardjo type Hardjo-bovis
• L. interrogans serovar Hardjo type hardjo-prajitno
• L. interrogans serovar Pomona
• L. kirschneri serovar Grippotyphosa
• L. interrogans serovar Icterohaemorrhagiae
• L. interrogans serovar Canicola

Transmission and Prevention

• Transmission of Leptospirosis

• Carried in the urinary tract which contaminates drinking water.

• Can penatrate mucus membranes

• Can shed through environment via aborted fetuses and fetal membranes

• Vaccine improves prevention by reducing reproductive issues

Clostridial Diseases

• Clostridial Diseases: “8-Way
• Anaerobic, spore forming, gas producing bacteria
• Ubiquitous = prevalent in soil and intestinal tract of mammals
• High mortality; unlikely to save the animal

Diseases

• Clostridium Chauvoie (Blackleg): common in young cattle

• Spores get ingested

• Disease progresses rapidly

• May/may not be associated with wound

• Clostridium Septicum (Malignant Edema): associated with wounds and reproductive trauma

• Bacteria found in feces of domestic animals

• can occur from C. sordelli, C. perfringens, C. novyi type B

• Clostridium Haemolyticum (Red Water Disease, Bacillary Hemoglobinuria) occurs when the liver is damaged

• Bacteria releases toxins that cause intravascular hemolysis and liver necrosis

• Spores in healthy animals, passed in feces/urine

• Concurrent infection with liver flukes

• Clostridium Novyi Type B (Black Disease) pathophysiology is similar to Red Water Disease

• Common finding is sudden death

• Clostridium Perfringens Type C (Necrotic Enteritis, Enterotoxaemia) found in young calves Worldwide disease and organism

• Clostridium Sordelli is founded in feedlot cattle and presents as sudden death

• Clostridium Tetani (Lockjaw) causes muscle spasms

Characteristics of Clostridial Diseases

• Clostridium chauvoie (Blackleg)*
• Young cattle
• Spread through ingested spores
• rapid disease
• Clostridium septicum (Malignant Edema)* Found in feces of domestic animals and soil with livestock.
• Fever, anorexia, swelling around a wound
• Clostridium hemolyticum (Red Water Disease)* Spores found in healthy animals (rarely), passed in feces/urine
• Liver damage
• Fever, anorexia, pale/icteric mucous membranes, port-wine urine.
• Clostridium novyi Type B (Black Disease)*
• liver is damaged anaerobic
• Sudden death Very similar disease to C. hemolyticum
• More common in sheep
• Clostridium perfringens Type C*
• intestial tract of animals.
• <1 week calves,
• Clostridium sordelli*
• feedlot cattle; Symptoms not observed, *~ acute death
• Black hemorrhage throat muscle necrosis with no gas formation

Clostridium tetani

• Causes disease when introduced into a wound
• Primarily a soil contaminant.

Treating Clostridial Diseases

• Treatment is challenging and costly
• Prevention is imperative
• Many multi-valent vaccines are available
• A.k.a: 4-Way, 7-Way, 8-Way, 9-Way, CD&T
• The vaccines come in the form of a Bacterin or toxoid. The vaccines require a a booster
• In general should booster 4-6 weeks with 6-12 months thereafter

ELISA

• ELISA tests look for antibodies

1. Coat well with antigen
2. Load positive and negative control
3. Add blood sample
4. Add wash step
5. Add enzyme-linked antibody
6. Add wash step
7. Add chromogen to see if color change

Rabies

• Rhabdovirus causes Rabies
• Mammals are susceptible
• Reservoirs skunks, raccoons, bats, fox, coyotes
• There are 2 types of vaccines (killed viruses and recombinant virus)
• Diagnosis has to be a post-mortem exam
• Rabies is excreted in saliva, or nervous tissue
• Transmission is through bites, scratches
• Clinical signs
• 2-3 incubation period of
• Behavior changes a few days
• 3-4 days excitory, or dumby form
• Rabies is fatal and a Zoonotic
• Follow the state and local laws

Other Diseases

• Canine distemper, paramyxvirus, reservoirs domestic wild dogs. Prevention with MLV or recombinant vaccine, direct contamination. Mild cases may be subclinical, and or there maybe poor tooth enamel development
• Hepatiatis or CAV-1, prevention MLV vaccine, asymptotic (death), bleeding disorders
• Caine Pavovirus- types 2/2b. Dogs and some cats, prevent with diagnosis
• Kennel cough-bordettela bronshiseptica. purainfluenza & CAV-2, dog can have this
• Leptiosproisis, is caused through spirochete, through dogs cats and humans. There are multiple carrier
• Feline Panleukpoenia- a parvovirus, from skunks, raccoons bats and foxes. causes feter dehydration and sudden death
• Feline rhinotracheitis- caused by herpes- sneezing, sneezing
• Feline leukemia virus- close cat to cat disease
• Feline immunodeficiency virus (FIV)- "fighting cat disease"

BVDV (Bovine Virial Diarrhea Virus)

Is a viral infection of cattle that can cause immunosuppression. There are 2 types: 1 and 2, they can be cytopathic (cell death) or non-cytopathic (no damage to cell)

• Respiratory illness- component of BRDV
• Embryonic loss- abortions
• The can get infected in utero with NCP BVDV can becmome calf infected that will not shed or clear the signs
• Muocsals dsiseasee causes

Wounds

Wound Healing Phases

• Inflammatory Phase: clot forms and cell removing bacteria
• Proliferative Phase; granualtion tissue is built as a barrier
• Maturation Phase; wound becomes elasticated; helps with durability

Immediate Wound Care

• Cover with bandage
• Hairs must be removed before wound dressing

Lavage

1. Why a. Remove derbies from loos particles b. Reduce bacteria
2. How it is done a. Flush with large volume/no antibiotics b. 7-8 pi lavage solutions;

• dilute chlorohexine

Wound Closure

1. Time
2. deglree of damage
3. amt of damge
4. blood to wound
5. location

How to primary wound closer,

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after care;

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