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35 Cards in this Set
- Front
- Back
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antigens
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viral proteins, glycoproteins which host immune responses are mounted against
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antigenic determinants or epitopes
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discrete parts or components of viral proteins
elicit neutralizing antibodies |
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T-lymphocytes: two major classes
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Regulator: helper (Th), suppressor (Ts)
Effector: cytotoxic (Tc), delayed hypersensitivity (Td) |
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Antigen presenting cells (APC)
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processing/presenting viral antigens to T cells (macrophage, monocyte, dendritic cells)
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MHC proteins
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MHC-I = present on the plasma membrane of most cells
MHC-II = present on the antigen presenting cells (APC) |
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cytokines
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soluble proteins produced by T cells, macrophages, monocytes
regulate, augment, or suppress immune function inhibit or enhance viral gene expression |
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Immunologic memory
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primary response sensitized T cells, clonal expansion to produce long-lived memory T lymphocytes
when exposed to same antigen, anamnestic immune response -> more rapid and vigorous, higher level response |
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Natural Killer (NK) cells
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large granular lymphocytes: destroy virus-infectecd cells
No specficity no memory no MHC- or antibody-dependence |
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Complement
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serum components ->complementing immune response
two pathways (classical Ag-Ab; alternate Ab-independent) destruction of virus-infected cells, inflammation, opsonization, neutralization enhancement |
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Active Immunity
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infected subject mounts immune response
destruct infected cells neutralize infectious viruses produce interferon |
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passive immunity
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infected subjects receive antibodies or activated T cells (products of other subjects' reaction to viral infection)
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Immune cytolysis of virus-infected cells
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occurs before mature virions are produced because of the appearance of early viral proteins on cells via 4 mechanisms
cytotoxic T cells antibody-complement complex mediated cytotoxicity antibody-dependent cell mediated cytotoxicity NK cells |
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Cytotoxic T cells
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release perforin to disrupt cell membrane integrity
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antibody-complement complex mediated cytotoxicity
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low level of antibodies via Classical pathway
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antibody-dependent cell-mediated cytotoxicity
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mediated by Fc receptors on leukocytes, macrophages, PMNs, NK cells
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NK cells
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activated by interferon or viral glycoproteins
non-specifically kill virus-infected cells |
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Neutralizing antibodies
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antibodies against viral attachment proteins (VAPs)
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Viral attachment proteins/epitopes
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recognizing cell surface receptors
specific binding |
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Antibody neutralization
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- at attachment/entry stage -> require large amount of antibodies
-antibody-virus complexes destroyed by cellular enzymes -> more effective |
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Recovery from viral infections: Tcells
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major protective roles in many diseases
broader specificity than antibody -depleted: no recovery -repopulated by adoptive transfer: recovery |
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Recovery from viral infections: antibody
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IgA: LOCAL - mucosal diseases
IgG: SYSTEMIC spread/ VIREMIA systemic disease virus in cells not affected by Ab |
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Passive immunity
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infected subject receives immune products -> antibody or activated T cells
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Natural vs Acquired Passive Immunity
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acquired in mammalian species by suckling (colostrum, milk) and in avian species via the egg yolk
maternal antibody - important for young animals: --trans-placental, colostral (IgA) and milk (IgG), egg yolk ---early suckling, continuous suckling (important for protection of young animals) protective for variable length of time after birth may interfere with vaccinations of young animals!!!! |
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IgA
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secreted IgA: present in respiratory, GI
important against localized infections (intestinal diseases or respiratory diseases) maternal or lactogenic immunity -> rapid decline in colostrum |
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IgG
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transplacental, translocation across GI epithelium
providing systemic protection against viremia and systemic disease digested and lose their activity inintestines Translocation: short duration, higher titers of IgA, IgG are important for protection maternal antibodies rapidly destroyed in newborns -> good management (early and continuous suckling) is important in the first few hours or days of the newborns |
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Human vaccination
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cost per dose is a low priority
safety, efficacy - highly controlled/top priority small number of vaccines available large international efforts |
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animal vaccination
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cost is a top priority
safety and efficacy is important limited international efforts over 80 vaccines |
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animal vaccine types
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Modified live-attenuated vaccine (MLV)
killed vaccine subunit vaccine genetically-engineered/recombinant vaccines |
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MLVs vaccines
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most effective: mutants naturally occured or induced by genetic engineering, serial passaging in cells or heterologous animal hosts
administered by SC, IM, orally, aerosol, drinking water Risks: safety - insufficient attenuation, contamination, reversion efficacy - depends on virus replication Stability - improper handling->ineffectiveness |
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Killed Vaccines
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ADV: safe, use in situations where MLVs not appropriate
DIS: incomplete inactivation multiple injections low level and shorter duration of immunity |
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Enhancing Immunogenicity: Adjuvants
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immune enhancers mixed with subunit, inactivated, synthetic vaccines to enhance immunogenicity
- prolonged retention and slow release - macrophage activation - attract lymphocytes leading to lymphokine secretion |
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Recombinant DNA technology
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genes of protective proteins identified, cloned, and expressed in bacteria, virus, or yeast
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Recombinant viruses as vaccines
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rabies vaccine (rabies viral antigen in vaccinia virus)
porcine circovirus (PCV) vaccine --- which is a chimeric virus with the immunogenic antigen of the pathogenic PCV2 expressed in the backbone of the non-pathogenic PCV1 |
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Suvaxyn PCV2 One Dose - Label claim
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first USDA-fully licensed vaccine
one dose vaccine (based on PCV1-2 chimera virus) for piglets 4 wks and older aids in the prevention of PCV2 viremia and the control of diseases caused by PCV2 |
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Antiviral agents
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cost-prohibitive for use in veterinary medicine
very few available |
