Term
| What is the most difficult barrier in the body to penetrate? Why? |
|
Definition
-skin
-cells on the surface are dead and thus do not allow for viral replication |
|
|
Term
| The majority of viral infections occur through contact with what? |
|
Definition
|
|
Term
| How do respiratory epithelial cells fight viral infection? |
|
Definition
| -covered in a blanket of mucus for trapping pathogens and moving it towards opening |
|
|
Term
| How does the digestive tract fight pathogens? |
|
Definition
| -digestive enzymes, acidic pH of stomach, and emulsifying properties of bile all delp |
|
|
Term
| What are the 2 most important components of the innate immune system to fight infections? |
|
Definition
-interfeons: IFN-alpha and IFN-beta
-natural killer cells |
|
|
Term
| Unlike the adaptive immune response, the innate immune response is (non-specific/specific) in that it recognizes (all/some) viruses. |
|
Definition
|
|
Term
| What is the most important arm of the inante resistance to viruses? |
|
Definition
|
|
Term
| What produces IFN-alpha and IFN-beta? |
|
Definition
|
|
Term
|
Definition
| -activated NK cells and Th cells |
|
|
Term
| IFN-alpha and IFN-beta are produced in what two situations? |
|
Definition
-infected cells which detect components of viral infection within them
-cells of the innate immune system which detect presence of the virus via tool-like receptors |
|
|
Term
| What do macrophages and dendritic cells recognize as PAMP molecues in the IFN system? |
|
Definition
|
|
Term
|
Definition
| -internally on endosomes and bind to PAMP molecules after phagocytosis |
|
|
Term
| What happens after TLRs are activated? |
|
Definition
| -they phosphorylate Nuclear Factors that initiate the transcription of mRNAs that thranslate IFN-alpha, IFN-beta, TNF-alpha, IL-12, and IFN-gamma |
|
|
Term
| dsRNA also causes macrophages, dendritic cells, and lymphocytes to maufacture ______ that are multiprotein oligomers which includes Caspase 1. What do they do? |
|
Definition
-inflammasomes
-promote inflammation by promoting the maturation of inflammatory cytokines |
|
|
Term
| True or FAlse: IFN-alpha and IFN-beta are active in the induced cell. |
|
Definition
| -FALSE, they are not anctive in the induced cell, the are transported out |
|
|
Term
| What happens to IFN-alpha and IFN-beta after they leave the induced cell? What is the purpose of this? |
|
Definition
-they bind to surface receptors of non-infected host cells and induce the production on antiviral proteins
-it is these antiviral proteins that cause the cells to resist a viral infection |
|
|
Term
| The antiviral proteins induced by IFNs consist of three enzymes. What are they? |
|
Definition
-2-5(A) synthetase
-protein kinase (PK-1)
-RNase L enzyme |
|
|
Term
| The antiviral protein enzymes are present in the cytoplasm in an (active/inactive) form. How are they activated? |
|
Definition
-inactive
-they are activated only when viral dsRNA is detected if the cell is infected by a virus |
|
|
Term
| What does 2-5(A) synthetase do? What does that do? |
|
Definition
-sytnesizes 2-5(A)
-activates RNaseL which chews up viral mRNAs |
|
|
Term
| What does protein kinasee (PK-1) do? What does this do? |
|
Definition
-phosphorylates the translation initiating factors (eIF-2) which binds to viral mRNA
-prevents viral protein translation |
|
|
Term
| Are IFN-alpha and IFN-beta directly or indirectly antiviral? |
|
Definition
|
|
Term
| Are IFNs broad or narrow spectrum? Potent or no? |
|
Definition
|
|
Term
| In general, how do IFNs work? |
|
Definition
-induce cellular antiviral enzymes in non-infected cells that become activated ONLY BY VIRAL dsRNA
-destroys the virus through activated enzymes that digest viral RNA and prevent viral protein synthesis |
|
|
Term
| NK cells are large granular __(type of cell)__ that exhibit spontaneous ______ against ______. They make up ___% of the circulating leukocytes. |
|
Definition
-lymphocytes
-vytotoxicity
-viral infected cells
-10% |
|
|
Term
| Do NK cells need to be sensitized to a particular virus before they attack and kill the viral-infected cell? |
|
Definition
| -NO, they have the potential to recognize and kill all viral infected cells |
|
|
Term
| What are the three important NK cell receptors that play a role in viral immune response? What do they do? |
|
Definition
1)m Natural Cytotoxic Receptors (NCR): recognize and bind to peplomers on viral infected cells
2) Inhibitory MHC-I receptors: recognize MHC-1 naturally present on all host cells
3) Fc receptors: bind to Fc portion of Ab that have attached to peplomers on viral infected cells |
|
|
Term
| Which of the 3 receptors on NK cells is the dominant receptor? How is it activated and what does it do? |
|
Definition
-MHC-1 Rc
-activated by the presence of normal MHC-1 molecules on cells
-prevent the NRC from activating the NK cell |
|
|
Term
| How do MHC-I and NCRs work together? |
|
Definition
-if NCRs are activated by viral infected cells that do not display MHC-I, the NK cell will kill the cell
-if the NCR binds to a cell that does display MHC-I, it will stop the activation of NK cell thus sparing the cell |
|
|
Term
| How do NK cells kill viral infected cells? |
|
Definition
| -secrete perforin and inject granzymes to activate the apoptosis cascade |
|
|
Term
| What is Antibody Dependent Cell Cytotoxicity (ADCC)? |
|
Definition
| -when an NK cell bind to Fc receptors of any Ab that is bound to viral infected cells thus inducing the perforin/gransyme pathway |
|
|
Term
| Other than cell binding, what else can activate NK cells? |
|
Definition
| -IFN-alpha, IFN-beta, TNF-alpha, IL-12, macrophages, dendritic cells |
|
|
Term
| What other function do activated NK cells serve in addition to killing viral infected cells? |
|
Definition
| -secrete IFN-gamma to help recruit immune cells to the area of infection |
|
|
Term
| The level of IFN increases and peaks at __-__ days post-infection when viral replication is at its peak. |
|
Definition
|
|
Term
| The NK cell activity is detected early during infection and peaks at about __ days. |
|
Definition
|
|
Term
| The adaptive immune response is not usually detected before __-__ days after virus inofulation in an acute viral infection. Its appearance coincides with what? |
|
Definition
-7-10
-decrease in virus excretionor replication |
|
|
Term
| Which immunoglobulin is important in primary response to viral infection but quickly drops off? What does it do? |
|
Definition
-IgM
-activates complement and is important in opsonization, neutralization, and agglutination of virus particles |
|
|
Term
| What does the presence of serum IgM indicate? |
|
Definition
| -that the animal is undergoing an acute active infection with a virus |
|
|
Term
| Describe the functions of IgG. How long does it persist in the body? |
|
Definition
-enters tissue spaces during inflammation and escapes into damaged mucosal surfaces
-opsonize, agglutinate, and neutralize
-last for a very long time in the body |
|
|
Term
| What is the function of IgA? What makes it well-suited to its job? |
|
Definition
-secretory Ab that protects mucosal sufaces
-trypsin resistant |
|
|
Term
| Describe the structure of IgA. |
|
Definition
| -dimers with J-chain and secretory piece |
|
|
Term
| What does IgA do to viruses? |
|
Definition
-agglutinates and neutralizes them, preventing viral adherence
-important in lactogenic immunity |
|
|
Term
|
Definition
| -the animal has no circulating antibodies to a particular virus |
|
|
Term
|
Definition
| -the animal has circulating Abs to a particular virus |
|
|
Term
| What is the term used to describe when an animal changes form seronegative to seropositive? |
|
Definition
|
|
Term
| What are the 4 methods by which antibodies prevent viral infection? |
|
Definition
-neutralization
-lysis of virus
-aid in phagocytosis
-caus lysis of host cells |
|
|
Term
| Definition: Neutralization |
|
Definition
-Ab binds to epitopes on the virion surface and prvents viral attachment ot the cells
-also cause conformatioal changes in capsid and agglutination of virus particles |
|
|
Term
| What happens during Ab lysis of viruses? |
|
Definition
| -Ab bound to virus particle (enveloped virus) activates the complement cascade, whch results in viral lysis |
|
|
Term
| How do Abs aid in phagocytosis? |
|
Definition
-Abs arm macrophages or opsonize viral particles or viral-infected cells
-the Fc receptors on the macrophages bin to the Abs and initiate phagocytosis
-can also activate the complement system |
|
|
Term
| How do Ab's cause lysis of the host cell? |
|
Definition
| -Abs bind to virrus infected cells and cell becomes lysed bo complement or ADCC involving lymphocytes (NK cells and CTLs), neutrophils, or macrophages |
|
|
Term
| Why does lysis of host cell work to stop viral infections? Doesn't it just release the virus to infect another cell? |
|
Definition
| -cells are lysed before virus particles are released by the infected cell (before they have actually made anything) thus preventing virus spread |
|
|
Term
| How is Cell mediated immunity (CMI) regulated? |
|
Definition
| -through T-cells via secretion of cytokines |
|
|
Term
| True or False: Severe malnutrition can affect CMI response and enhances severity of diseases |
|
Definition
|
|
Term
| Cytotoxic T lymphocytes (CTL) are detcted __-__ days following viral infection. |
|
Definition
|
|
Term
| CTLs respond to (endogenous/exogenous) antigens. |
|
Definition
|
|
Term
| What do CTLs recognize on viral infected cells and how does it get there? |
|
Definition
-recognize cognate peptide:MHC molecule
-during virus replication, small biral peptides are formed which bind to the groove on the MHC_I molecules and are transported to the cell surface to flag down said CTL |
|
|
Term
| What do CTLs do once they are activated? |
|
Definition
| -lyse any viral infected cell |
|
|
Term
| T-helper cells produce ______ that activate ______. What does this cause? |
|
Definition
-cytokines
-B-cells and T-cells
-causes proliferation of said cells those receptors have recognized and bound to specific viral antigens |
|
|
Term
| What are Th1 cells primarily responsible for? What about Th2? |
|
Definition
-stimulating cell-mediated immune responses
-stimulating a humoral immune response to viruses |
|
|
Term
| What must happen for memory T-cells to be stimulated? |
|
Definition
| -virus must replicate so that the Ag can be presented to the MHC-I and MHC-II molecules |
|
|
Term
| -True or False: In a sensitized animal, antibodies are important in diminishing the virus load thereby reducing the number of cells the virus can infect. |
|
Definition
|
|
Term
| What do T-cells do in an effort to minize virus relase and ease the load on the antibodies? |
|
Definition
| -recognize and eradicate the infected cells before the virus has a chance to mature |
|
|
Term
| Is cell-mediated or humoral immune response important in eliminating virus during viral infection? What about in preventing viral infection? |
|
Definition
-cell-mediated = elimination during infection
-humoral = prevention of infection |
|
|
