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Give the 5 basic characteristics of Viruses
1. genome of either RNA or DNA
2. Obligate intracellular parasites
3. Composed of nucleic acid and proteins
5. Not susceptible to antibiotics
List the 7 basic steps of replication
4. Replication of proteins
5. Replication of nucleic acids
What is it called when an individual is infected but you cannot see s/s of disease yet?
How does adhesion work?
attachment of virus to host cell via receptors like the primary receptor and the co-receptor
what is the difference between class IV and class VI viruses?
Class 6 has reverse transcriptase in it
what are the 2 rounds of transcription in DNA viruses?
one from parental DNA and one from progeny DNA
why can replication of RNA take place in the cell cytoplasm?
The RNA viruses carry their own polymerases
what factors determine viral pathogenesis?
cell susceptibility, tissue tropism, immune resistance factors
What do receptors determine?
the presence of receptors determine whether a virus will infect your lungs or kidneys or liver etc.
what cells are in charge of humoral and cell-mediated immunity?
B cells- humoral
T cells- cell-mediated
what happens when a cell become virally infected?
the cell then expresses viral antigens and is considered "foreign".
what happens when a virus changes?
antigen changes, surface proteins change, change in susceptibility to drugs
what does an antigen drift of influenza cause?
epidemics, that's why there must be a new vaccine every year
how are influenza strains named? ex: A/Fujian/411/2002 (H3N2)
virus type, geographic origin, strain number, year of isolation, virus subtype
list the 6 cytopathic effects of gene switching?
1. inclusion bodies
2. cell lysis
3. cell rounding
4. syncytia formation
the change of normal cells to cells exhibiting the properties typical of tumor cells
what change in behavior happens during transformation
contact inhibition- cells touch and stop growing
what change in growth patterns happen during transformation
cells are pushed through checkpoints in cell cycle so they keep growing regardless of mutations
what happens in the 5 stages of the cell cycle?
G1: growth phase, RNA and Protein synthesis
G0: resting stage
S: DNA replication
G2: RNA and Protein synthesis
how is the cell cycle controlled?
through checkpoints that regulate the progression of cell from one stage to another
what are the 5 normal functions of oncogenes?
growth factor receptors
cell cycle and cell death regulators
when does virus-induced transformation occur?
tumor suppressors are inactivated
enhancement of growth factors
how are growth activators enhanced?
viral oncogenes are incorporated into the host genome.
viral DNA is incorporated near a proto-oncogene
what are the 9 steps of HIV replication?
2. penetration and uptake via gp41
3. Reverse transcription in cytoplasm
4. DNA replication
5. Move into nucleus for integration into host chromosomes as provirus
6. Host transcription factors bind LTR. Cytokine secretion by immune cells can enhance HIV transcription
8. Budding of immature viral particle
9. Long proteins are cleaved by viral proteases now making the virus infectious
what are the 3 causes of immunodeficiency by HIV?
altered cytokine/chemokine secretion
CD4 cells susceptible to HIV are found in what 5 places:
follicular dendritic cells
what 4 common diseases are associated with HIV infections?
what are characteristics of an ideal antimicrobic:
soluble and active in dilute concentrations
not susceptible to antimicrobial defenses
complements host defenses
does not compromise the host
what is C diff and how do you get it?
clostridium difficile, get it by overuse of antibiotics. causes psudomembranous colitis
what are side effects of host/drug reactions
toxicity ( renal/hepatic) allergic responses, alteration of microflora
what is the function of normal microbiota?
modification of pH and oxygen tension
creating physical obstacles
stimulating immune system
where are sources of normal microbiota?
skin, alimentary tract, respiratory tract, genitourinary tract
what are microbe-free body sites that should be sterile?
muscles, nervous system, blood, some internal organs
what factors promote disease?
adherence factors such as capsules and fimbriae, extracelllar enzymes, bacterial toxins, intracellular survival, infectious dose
why are intracellular organisms harder to kill?
they can evade immune response by growing inside organisms
what is an example of a chronic carrier?
organisms resides permanently and is shed through fecal matter
what is an example of a passive carrier?
picks up organism and then transfers to another without knowing. classic example is a dr. or ns
what is a biological vector?
involved in the life cycle of the pathogen, for example mosquito, tick flea
what is a mechanical vector?
involved in the physical transmission of the pathogen. example flies and roaches
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