HY bact and vir

jdlevenson's version from 2015-06-09 06:12


HY Virology


Question Answer
All DNA are DS exceptParvo
All RNA are SS exceptReo/ Rota
Only () viruses can cause antigenic shiftSegmented
What segmented viruses existOrthomyxo (flu) and Rota (Reo)
Antigen drift happens inAll viruses. Single pt mutation.
HDV needing HBsAg of HBV is calledComplementation
When there is nucleocapsid from one strain with genome from another that is calledPhenotypic mixing; next generation reverts back to original unmixed phenotype.
A cytopathic wild type virus can occur fromReecombination (2 viruses infected same cell; crossing over occurs at homologous regions) and Reassortment (only for segmented viruses)
All RNA viruses replicate inCytoplasm except influenza and retroviruses
All DNA viruses replicate inNucleus except pox (smallpox, cowpox)
Enveloped viruses acquire their envelope fromPlasma membrane, except Herpes viruses which acquire envelopes from nuclear membrane
All DNA viruses are linear exceptPapilloma (HPV), polyoma (JC) and hepadna (HBV)
All DNA viruses are icosahedral exceptPox (smallpox cowpox)
All picorna viruses can cause aseptic viral meningitis exceptRhinovirus and HAV
All picorna viruses are enteroviruses exceptRhino


HY Bacteriology
Question Answer
Unique to gram positiveLipoteichoic acid
Unique to gram negativesPorin, endotoxin/ LPS (outer membrane) and periplasmic space (where Beta lactamase is located)
Common to gram negatives and positivesFlagellum, pilus, capsule, cell wall, peptidoglycan and cytoplasmic membrane
Why is pilus/ fimbria importantMediates adherence of bacteria to cell surface; sex pilus forms attachement between 2 bacteria during conjugation
Vilus shows variation inN. Gonococcus/ antigenic variation
Viruses that express antigenic variationInfluenza, HCV, HIV
What bacteria has 2 flagella variantsSalmonella***
Capsules are organized discrete polysaccharide layers exceptBacillus anthracis which contains D-Glutamate
Why is glyocalyx importantMediates adherence to surfaces, particularly foreign surfaces like with indwelling catheters; made up of loose network of polysac
Gram negatives have an outer membrane that has key endotoxinLPS, major surface antigen with toxic portion being Lipid A that is generally not released until death of cell (except with N. Meningitis, overproduces outer membrane) and O polysaccharide as antigen
LPS activatesMacrophages, leading to release of TNFalpha, IL-1 and IL-6; IL-1 – fever, macrophage activation and production leads to tissue damage, and damage to endothelium from bradykinin induced vasodilation leads to shock
Pleomorphic bacteriaChlamydia and Rickettsia
Periplasm is inGram negatives; space between cytoplasmic membranes and outer membrane
Why are polysacchardies conjugated to carrier protein :To promote immunogenicity since polysaccharide antigen alone cannot be presented to T cells
Question Answer
Conjugate vacinesH Flu, Meningococcal, Pneumococcal
What bacteria produces red? Blue-green?Red – serratia; blue-green – pseudomonas
Protein A is expressed byS. Aureus
Protein A has what effectBinds Fc region of IgG; prevents opsonization and phagocytosis.
Group A strep have what virulence factorM Protein; prevents phagocytosis; shares similar epitopes to human cellular proteins via molecular mimicry; possibly underlies autoimmune response seen in ARF
Type III secretion systemInjectisome – pseudomonas, salmonella, shigella, e. coli
Only () have ENDOtoxinGram negative; lipopolysac, released when lysed ; recall Gram positive and negative have EXOtoxin
LPS endotoxin, toxicity? Antigenicity?Low toxicity; need A LOT to be toxic; poorly antigenic
Which is heat stable, exotoxin or endoEndo.