Bacteria Bacteria – single-celled organisms that are prokaryotic (no true nucleus)
Immunity to bacteria and related organisms in animal
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Transcript of Immunity to bacteria and related organisms in animal
Acquired Immunity to Bacteria and Related Organisms
Pakawadee Kumpolngam D.V.M.
• Acquired immunity– Immunity to Toxigenic Bacteria– Immunity to Invasive Bacteria– Immunity to Intracellular Bacteria– Modification of bacterial disease by immune responses
• Evasion of the immune response– Prevention of recognition– Resistance to effector mechanisms
• Adverse consequences of the immune responses• Serology of bacterial infections• Immunity to fungal infections
Acquired-immune responses to bacterial infection
There are 5 basic mechanisms• Neutralization : toxins or enzymes by
antibody• Killing bacteria : antibodies and complement• Opsonization : by antibodies and
complement, resulting phagocytosis and destruction
• Intracellular destruction : by activated macrophages
• Direct killing : by cytotoxic T cells and NK cells
Acquired immunity
The mechanisms by which the immune responses can protect the body against bacterial invasion.
Acquired immunity
• Immunity to Toxigenic Bacteria– Toxigenic bacteria such as B. anthracis– Immune response eliminate bacteria and
neutralize their exotoxins– Neutralization : Antibody prevents Toxin from
binding to its receptors on a target cell.– Once the toxin has combined with receptors,
antibodies ineffective in reversing this combination.
Immunity to Invasive Bacteria• Alternative or lectin pathways : innate defense mechanisms
-> MAC -> Lysis• Antibody and Complement activate Classical pathway to
destroy bacteria -> MAC -> Lysis• Antibodies or C3b against surface antigens of Bacteria :
capsular (K) antigen or cell wall (O) antigen– Antibodies or C3b act as opsonins
• Opsonization : antibodies and complement against bacteria resulting phagocytosis by neutrophils and macrophages
• Bacteria are either opsonized or lysed
Immunity to Intracellular Bacteria• Bacteria can evade intracellular destruction
Immunity to Intracellular Bacteria
Evasion of the immune response
1. Avioding antibody- Change protein surface- Produce protease destroy Ab.
2. Avoiding phagocytosis- Capsule protect macrophage - Produce protein interfere macrophage function
3. Avoiding complement4. Inhibit the expression of MHC I and II on DC surface
Immunity to Intracellular Bacteria
The type of immune response stimulated by bacteria depends on whether the bacteria are live or dead and whether they grow inside or outside cells.
IFN-γ
IL-2
Acquired immunity :Johne’s disease
• Modification of bacterial disease by immune responses
A.Lepromatous form-poor cell-mediated response -very high antibody levels-lesion contain so many bacteriaB.Tuberculoid form-intense cell-mediated response -minimal antibody response-lesion contain very few bacteria
(Mycobacterium paratuberculosis)
Modification of bacterial disease by immune responses
Immune response can swing between Th1 and Th2 response, perhaps several times, this variation appears to be a common feature of chronic infection such as tuberculosis.
Adverse consequences of the immune responses
• The adverse consequences of the immune responses correspond in their mechanism to the Hypersensitivity types described in next chapter.For example– a local Type I hypersensitivity– Type II cytotoxic reaction– Type III immune complex reaction
Serology of bacterial infections
• Detecting the specific antibodies– Bacterial agglutination tests
Immunity to fungal infections
• Innate immunity– Phagocytosis by
neutrophils and macrophages
– γδ T cells at epithelium – NK cells
• Adaptive immunity– Th1 response– Opsonization : antibody
induce phagocytosis
Acquired Immunity to Viruses
Acquired Immunity to Viruses
• Virus structure and antigens• Pathogenesis of virus infections• Immunity to virus• Evasion of the immune response by virus• Adverse consequences of immunity to viruses• Serology of viral diseases
Virus structure and antigens
• Viral antigensNucleic acid coreCapsid protein Envelope– Lipoprotein – Glycoprotein
• Cannot grow or reproduce without host cell
Innate immunity to Viruses• Interferons
The sequential production of interferon and antibody following intranasal vaccination of calves with infectious bovine rhinotracheitis vaccine. (From data kindly provided by Dr. M savan.)
Innate immunity to Viruses1. Interferons • Type I IFN : IFN α, β, τ and δ• Type II IFN : IFN γ (gamma)• IFN α/ß are released from virus-
infected cells or plasmacytoid DCs – stimulate autocrine and
paracrine into antiviral stages• IFN γ released from NK cells and
Th1 cells – stimulate cytotoxic T cells and
Macrophages
Innate immunity to Viruses
2. NK cells• NK cells cytotoxicity is stimulated by IFN α• NK cells produce IFN γ -> antiviral effect• NK cells reduce severity of viral infection before the
development of acquired immunity
Immunity to virus
Antibody-Mediated Immunity
Cell-mediated Immunity
Interferons
NK cells
Immunity to virus
Evasion of the immune response by viruses
• Inhibition of Humoral immunity– They undergo mutation, selection and change the
structure of their hemagglutinins and neuraminidases : H16 N9 (2011)
– Antigenic drift / Antigenic shift (Antigenic variation)
• Interference with Interferons and Antibody• Inhibition of Apoptosis– Virus can replicate in infected cells
• Inhibition of Cytotoxic T cells and NK Cells– Inhibit mature DCs and induce DCs dead
• Latency : HIV
Inhibition of Humoral immunity
Adverse consequences of immunity to viruses
• Infectious canine hepatitis – Canine adenovirus 1
• Feline Infectious Peritonitis (FIP)– Coronavirus
Adverse consequences of immunity to viruses
Infectious canine hepatitis
Adverse consequences of immunity to viruses
Feline Infectious Peritonitis (FIP)
Immune-complexes deposite in serosal blood vessel causing
Pleuritis Peritonitis Glomerulonephritis
Serology of viral diseases
• Test to detect and identify Viruses and Antibodies– Immunofluorescence – ELISA– HA, HI– Gel precipitation– Western blotting– Complement fixation– Virus neutralization
Immunity to Parasites
http://www.huldaclarkzappers.com/php2/therapies.php
Immunity to Parasites
• Immunity to Protozoa– Innate immunity– Acquired immunity– Evasion of the immune response– Adverse consequences– Vaccination
Immunity to Protozoa
Innate immunity• In vertebrates, extracellular protozoa are eliminated
by phagocytosis and complement activation. • T cell responses.
- Extracellular protozoa - Th2 cytokines released for antibody production.
- Intracellular protozoa - Cytotoxic lymphocytes (CTL’s) kill infected cells. Th1 cytokines produced to activate macrophages
Immunity to ProtozoaAcquired immunity• Antibody responses.
- Extracellular protozoa are eliminated by opsonization, complement activation and ADCC. - Intracellular protozoa are prevented from entering the host cells by a process of neutralisation e.g. neutralising antibody against malaria sporozoites, blocks cell receptor for entry into liver cells.
Immunity to Protozoa
• Acquired immunity• Th1 response for
intracellular parasite• T. gondii tachizoites
grow within cells, the infected cell rupture and tachizoites are released to invade other cells.
Immunity to Protozoa
• Acquired immunity
The points in the life cycle of Toxoplasma gondii at which the immune system can exert a controlling influence.
Immunity to Protozoa
• Evasion of the immune response1. Avoid antibody
- Trypanosomes with a new surface glycoprotein antigen
2. Avoid neutrophil attachment and phagocytosis- T. gondii inhibit lysosome-phagosome fusion
3. Many protozoa are immunosuppressive- Plasmodium suppress DCs to process antigen
Immunity to Protozoa
• Adverse consequencesHypersensitivity types – Type I hypersensitivity– Type II cytotoxic reaction– Type III immune complex reaction– Type IV hypersensitivity reaction
Immunity to Protozoa
• VaccinationSuccessful vaccination against protozoan
infections of domestic animals is currently limited to coccidiosis, babesiosis, giardiasis and theileriosis
Acquired Immunity to Parasites
• Immunity to Helminths– Humoral immunity– Eosinophils and Parasite destruction– Cell-mediated immunity– Evasion of the immune response– Vaccination
Immunity to Helminths
• Most helminths extracellular & too large for phagocytosis.
• For the larger worms, e.g. some gastrointestinal nematodes host develops inflammation and hypersensitivity.
• Eosinophils & IgE activated to initiate inflammatory response
• Mast cells release histamine elicited reactions are similar to allergic reactions.
Immunity to Helminths• Humoral immunity
The mechanisms involved in the self-cure reaction against intestinal helminths.
Immunity to Helminths
• Horse skin allergy by migrating parasitic helminth larvae.
• Eosinophils presence• Type I hypersensitivity
Immunity to Helminths
• The factors involved in the activation of eosinophils– Granulocyte-macrophage
colony-stimulating factor (GM-CSF)
– EAF ; Eosinophil Activating Factor
– PAF ; Platelet-Activation Factor
Immunity to Helminths
• Eosinophils and Parasite destruction
Some of the molecules released from eosinophils that cause damage to parasitic helminths.
Immunity to Helminths• Eosinophils and Parasite destruction
Some effects of the immune responses on the stages of helminth development.
Immunity to Helminths• Cell-mediated immunity
Immunity to Helminths• Evasion of the immune response
Immunity to Helminths• Vaccination– Traditional vaccines little use– Recombinant T. ovis vaccine can induce protective
immunity in seep• Prevention – Control or prevent an infestation of helminths– Treat by drug
Antibody function and immune response to organisms
Acquired Immunity to Parasites
• Immunity to Arthropods– Demodectic Mange– Flea-Bite dermatitis– Tick infestation– Hypodermal infestation
Immunity to Arthropods
Demodectic Mange• T cell response• Infiltrating lymphocytes• Granuloma formation• Type I,IV hypersensitivity
reaction
• Flea-Bite dermatitis
© 2013 Campus Veterinary Clinic
Immunity to Arthropods
• Tick infestation
www.parasiticpests.com
Immunity to Arthropods
• Hypodermal infestation
• Hypodermin A, the protease secreted by larvae
• inhibit immune responses and reduce IL-2
Reference
• Tizard, I. R., 2009. Veterinary Immunology an introduction. 8th. Elsevier Saunders.
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