BVetMed1 Principles of Science Lecture Notes PDF

BVetMed1 Principles of Science FRAMEWORK LECTURE Basis of Infection & Immunity Brian Catchpole BVetMed MSc PhD FRCVS Prokaryote family tree Saprophyte Isaprophytes) X harmful only populates Symbiont Symbiotic mutually benferal b g ⑰ Commensal findly keeps unfiendly barteria Pathogen / Parasite karmf...

BVetMed1 Principles of Science FRAMEWORK LECTURE Basis of Infection & Immunity Brian Catchpole BVetMed MSc PhD FRCVS Prokaryote family tree Saprophyte Isaprophytes) X harmful only populates Symbiont Symbiotic mutually benferal b g ⑰ Commensal findly keeps unfiendly barteria Pathogen / Parasite karmful on : , banterna ,. ->. r e. In car dead. shomad out. organism. Primary pathogen e.g. Brucella abortus > - > - assorcate heads to of disease abortion in in host cows. directly found Opportunistic pathogen e.g. Mannheimia haemolytica > - when in host something body occurs starts g. e. infection damaged epithelium Main routes of transmission Contact: direct / indirect (skin to skin) Aerosol (resp tract to resp tract) Orofaecal (GIT to GIT) Vector-borne (blood to blood) Transplacental (mother to offspring) Sites of infection (surface dwellers) U/G TRACT GIT > - local infections RESP TRACT SKIN Some pathogens prefer to live on epithelial surfaces Other pathogens invade and infect tissues PATHOGEN IN INTRACELLULAR VESICLE PATHOGEN IN TISSUE FLUID PATHOGEN IN CYTOPLASM Host response to infection: Inflammation and Immunity Lymphoid tissues White blood cells Neutrophils (bacteria) Eosinophils (parasites) Basophils / tissue mast cells (parasites) immertime i develop Monocytes / tissue macrophages (bacteria) Lymphocytes (viruses). ↳ I can and other WBC The misama ↑ Review - Infectious disease = pathogen Robert Koch 1843 - 1910 VETERINARY PATHOGENS MICROBIOLOGY Viruses Bacteria Fungi / Yeasts PARASITOLOGY Helminths (worms) Arthropods (insects) Protozoa Prions Induces a conformational change in the normal prion protein in the host Build up of mutant protein leading to cell death and tissue damage (esp CNS) Transmissible Spongiform Encephalopathies (TSEs) - metohed poli BASIS OF INFECTION: VIRUSES Schmallenberg virus Virus structure (naked vs enveloped) found ente en protemshell of virus enclosing genetic materials. Extracellular contagious phase Spread from host to host Intracellular replication phase Synthesis of new virus particles Extracellular dissemination phase Spread from cell to cell Immunity to viruses B lymphocytes produce ANTIBODY Targets extracellular phases Binds to surface of virus and prevents attachment to target cell > prevent replication phase IgG = systemic protection IgA = mucosal protection I & -. protects resp abmentary tool. Killer T lymphocytes Targets intracellular phase Seek out and destroy virus-infected cells : prevents spread : stops replication. Treating viral infections Antibiotics do not work against viruses Antiviral drugs are expensive Vaccination Prevention is better than cure Vaccination Expose host to modified, killed or fragments of pathogen to educate the immune system into making a response, but without causing disease Immunity develops that protects the host, if exposed to real pathogen later in life... BASIS OF INFECTION BACTERIA Structure of bacteria : prokaryote ↳ diff antibiotic structure can target barteria. Life cycle of bacterial infection Infection Colonisation Invasion Dissemination to not of spreading smith widely Colonisation of epithelial surfaces Skin Respiratory tract GIT Urogenital tract Pyoderma (Staphylococci) Helicobacter pylori on gastric mucosa Invasion of tissues surface dwellers Breach of epithelial barrier. TRAUMA TOXINS Localised Infection Lymphatic Spread Haematogenous Spread by. blood stream Systemic Infection Localised invasion and replication Abscess pro-libe lesion Granuloma > - solved Bovine TB (Mycobacterium bovis). Lessons such resp a a desense Lymphatic spread Strangles - Streptococcus equi > - gets b travel O& carotid through -n mucosa lymph ↳ to hymph vabness lymph mode modes. vessels Septicaemia I blood porsoning Swine Erysipelas Erysipelothrix rhusiopathiae Some bacteria produce toxins: Clostridial diseases Tetanus Botulism Immunity to bacteria PHAGOCYTOSIS & DIGESTION Neutrophils Macrophages Phagocytosis is enhanced by ANTIBODY Treatment of bacterial infection > - selectively Anti-microbial drugs (antibiotics) Target prokaryotic structure or function toxic to prokaryotes. -microbial resistance is becoming more common On his way to the lecture, Bob was approached by the Antibiotic Resistance BASIS OF INFECTION PARASITES PARASITES ENDOPARASITES HELMINTHS Parasitic worms Mainly infections of alimentary or respiratory tracts PROTOZOA Microscopic parasites Often blood-borne infections spread by insect vectors ECTOPARASITES ARTHROPODS Fleas, lice, flies, mites and ticks Mainly infestations of skin Helminths: Lungworm Indirect life-cycle Protozoan parasite (vector-borne transmission) Leishmania infantum Zoonosis = also infects humans ARTHROPODS: Mites A mangey critter Demodex mite lives In eas > - hear hair how fallaches follies fall. & ARTHROPODS: Ticks IMMUNITY TO PARASITES 1 EOSINOPHILS MAST CELLS a IgE ANTIBODIES crite parasitic Treatment of parasite infections Anthelmintics (wormers) Ectoparasiticides (flea treatment) Anti-protozoal drugs Summary Not all microorganisms are pathogenic and cause disease Pathogens are very varied in their biology and life cycles The host immune system is designed to detect and eliminate infectious organisms There are a number of pharmaceutical products and vaccines designed to counteract infectious disease