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50 Cards in this Set
- Front
- Back
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major feature of innate immunity
presence of the normal flora in the GI, genitourinary, and respiratory tracts completely inhibit the binding of pathogens to host cells |
commensal organisms
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frequently form the first line of defense against viral infections
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NK cells
interferon production (IFN-alpha and -beta) |
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strategy of viruses in which the infection is is efficiently transferred during even a short acute illness
influenza and smallpox use this strategy |
facile transmission
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dsRNA molecules produced during the viral life cycle are detected by...
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TLRs
toll-like receptors which induce the the expression of IFN-alpha and -beta by the infected cell |
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activated by binding of IFN-alpha/beta to IFN alpha/beta receptor
in turn induces the transcription of several genes |
JAK-STAT pathway
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this enzyme activates a ribonuclease (RNAse L) that degrades viral DNA
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2'-5'-oligo-adenylate synthetase
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ribonuclease that degrades viral DNA
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RNAse L
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the binding of IFN-alpha and beta to ___ _____ induces lytic activity, making them very effective in killing virally infected cells
activity of ___ ____ is also greatly enhanced by IL-12, a cytokine that is produced very early in the response to viral infection |
NK cells
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PKR
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dsRNA-dependent protein kinase
leads to inactivation of protein synthesis |
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_____ ____ in mucous secretions plays an important role in host defense against viruses by blocking viral attachment to mucosal epithelial cells
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secretory IgA
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acts directly by inducing an antiviral state in cells
activates NK cells |
IFN-gamma
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acts indirectly by assisting in the development of CTL precursors into an effector population
activates NK cells |
IL-2
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hepatitis C evades the action of IFN-alpha/beta by blocking or inhibiting the action of ____
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PKR
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in particular, HSV (herpes simplex virus) inhibits antigen presentation by infected host cells
to do so, HSVs express an immediate-early protein called _______ which very effectively inhibits the human transporter molecule needed for antigen processing called ______ |
ICP47
TAP |
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inhibition of TAP blocks antigen delivery to class ____ MHC receptors on HSV-infected cells, thus preventing presentation of viral antigen to CD8+ T cells
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class I MHC molecules
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paramyxoviruses that cause mumps, the measles virus, epstein-barr virus (EBV), cytomegalovirus, and HIV all evade the immune system in this manner
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causing generalized immunosuppression
this may be through directly destroying immune cells by cytolytic mechanisms or altering their function in other cases, the immunosuppression is a result of a cytokine imbalance |
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EBV produces a protein called ____ that is homologous to IL-10, and similarly suppresses cytokine production by the Th1 subset, resulting in decreased levels of IL-2, TNF, and IFN-gamma
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BCRF1
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two glycoproteins inserted into the envelope of influenza virions
(surrounded by an outer envelope consisting of a lipid bilayer acquired from the plasma membrane of the infected host cell during the process of budding) |
hemagglutinin (HA) and
neuraminidase (NA) |
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the projections, in the form of trimers, are responsible for the attachment of the virus to host cells
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hemagglutinin projections
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hemagglutinin trimer binds to ____ ____ groups on host-cell glycoproteins and glycolipids by way of a conserved amino acid sequence that forms a small groove in the hemagglutinin molecule
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sialic acid
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cleaves N-acetylneuraminic (sialic) acid from nascent viral glycoproteins and host-cell membrane glycoproteins, an activity that presumably facilitates viral budding from the infected host cell
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neuraminidase
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within the envelope, an inner layer of ____ ____ surrounds the nucleocapsid
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matrix protein
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the nucleocapsid of influenza consists of...
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eight different strands of single-stranded RNA (ssRNA) associated w/ protein and RNA polymerase
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three basic types of ______ can be distinguished by differences in their nucleoprotein and matrix proteins
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influenza
(A, B, and C) |
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the most common type of influenza, is responsible for the major human pandemics
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type A
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this type of influenza causes human but not animal disease and has caused epidemics
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type B
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this type of influenza causes only mild human illness
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type C
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involves a series of spontaneous point mutations that occur gradually, resulting in minor changes in hemagglutinin and neuraminidase
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antigenic drift
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results in the sudden emergence of a new subtype of influenza whose HA and possibly also NA are considerably different from that of the virus present in a preceding epidemic
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antigenic shift
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this is the main protective response against extracellular bacteria
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the humoral immune response
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intracellular bacterial infections tend to induce a cell-mediated immune response; specifically, ____ _____ ______
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delayed-type hypersensitivity
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four primary steps in bacterial infection
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attachment to host cells
proliferation invasion of host tissue toxin-induced damage to host cells |
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secretory IgA antibodies role in bacterial defense
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secretory IgA antibodies specific for bacterial attachment structures can block bacterial attachment to mucosal epithelial cells and are the main host defense against bacterial attachment
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examples of bacterial surface structures that aid in attachment to mucosal surfaces
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pili
adhesion molecules that attach both the bacterium and the ciliated epithelial cells of the upper respiratory tract |
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the 84 _______ of S.pneumoniae differ from one another by distinct capsular polysaccharides
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serotypes
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enzyme which inactivates both the C3a and C5a anaphylatoxins, thereby diminishing the localized inflammatory response
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elastase
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cell wall endotoxins of some gram-negative bacteria activate macrophages, resulting in release of high levels o IL-1 and TNF-alpha, which can cause ____ _____
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septic shock
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the ability of some bacteria to survive intracellularly w/in infected cells can result in chronic antigenic activation of CD4+ T cells, leading to tissue destruction by a cell-mediated response w/ the characteristics of a _____ ____ ______ ______
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delayed-type hypersensitivity reaction
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diptheria is the classic example of a bacterial disease caused by a secreted exotoxin to which immunity can be induced by immunization w/ an inactivated _____
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toxoid
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tuberculosis is primarily controlled by _____ ____ ___
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CD4+ T cells
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the most common clinical patten of tuberculosis infection
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pulmonary tuberculosis
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in tuberculosis, CD4+ T cells induce the infiltration of large numbers of activated macrophages
these cells wall off the organism inside a granulomatous lesion called a ... |
tubercle
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in tuberculosis, as caseous lesions heal, they become calcified and are readily visible on x-rays, where they are called ____ ____
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Ghon complexes
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in this clinical pattern (10% individuals infected) accumulation of large concentrations of mycobacterial antigens w/in tubecles leads to extensive and and continual chronic CD4+ T=cell activation and ensuing macrophage activation
resulting high conc of lytic enzymes cause the necrotic tissue to liquefy, creating a rich medium that allows the tubecle bacilli to proliferate extracellularly |
chronic pulmonary tuberculosis
extrapulmonary tuberculosis |
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responsible for these serious diseases in humans:
amebiasis Chagas disease African sleeping sickness malaria leishmaniasis toxoplasmosis |
protozoans
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VSG
found in trypanosomes - flagellated protozoans that can cause sleeping sickness antigenic shift in these areas are the reason for recurring parasitemia |
variant surface glycoprotein
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Leishmania major
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provides an examples of how differing host responses can lead to either clearance or death from a parasite
Th1 is effective, while Th2 responses are not |
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parasitic worms
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helminths
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several Schistoma species are responsible for the chronic, debilitating, and sometimes fatal disease ______
most symptoms are caused by eggs, which can remain in the host causing chronic conditions including cell-mediated delayed-type hypersensitivity reactions, resulting in large granulomas that are gradually walled off by fibrous tissue |
schistosomiasis
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phagocytosis by _______ is a strong defense against most fungi
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neutrophils
those w/ neutropenia are susceptible to fungal infection |
