Microbiology (Bio 139) Exam Review Outline: Exam #4
Viruses. Retroviruses: totally different from other ssRNA genome viruses: they make dsDNA (reverse
transcription) & integrate as provirus. Antigenic drift vs Antigenic shift in influenza A viruses.
Hemagglutinin & Neuraminidase: important surface antigens on the surface (envelope) of influenza that
distinguish one strain from another
AIDS: & HIV: abbreviations for what? What kind of virus is HIV?(retrovirus) What kind of genome
does it have?(ssRNA) What enzyme does it provide to convert its RNA into DNA?(reverse transcriptase,
an RNA-dependent DNA polymerase) Where does the HIV genome go once it is made into DNA?(it
integrates into the infected cell’s genome as a provirus) What cell surface marker does HIV use to enter a
cell?(CD4) What cells are CD4+?(T helper lymphocytes; macrophages) What kills most AIDS
patients?(opportunistic infections or cancers due to immunodeficiency, their immune systems fail) What
part of the world currently has the highest AIDS prevalence rates?(southern Africa) How is HIV
primarily transmitted there?(heterosexual sex) What “problem” does HIV have that makes it difficult to
design a vaccine?(high mutation rate due to inaccurate polymerase activity of RT)
Hantavirus. Emerging viral disease in U.S.; zoonosis (rodents). Herpesviruses (herpes simplex &
varicella zoster): latency in neurons; reactivation (immunosuppression, other) as herpes or shingles
(dermatome distribution of rash). Hepatitis A: fecal-oral, common in CA. Hepatitis B: sex & blood. D:
defective virus, needs helper (hep B). What virus has been eradicated? (smallpox) What virus is targeted
for eradication? (polio) because no reservoir outside humans, good vaccine available. Next target for
eradication: Polio: fecal-oral transmission; causes paralysis in some cases.
Viruses & cancer: prefix onco-; what is cancer/neoplastic transformation? What is the difference
between a proto-oncogene and an oncogene? 3 mechanisms by which viruses can cause cancer: DNA
tumor viruses (integration into host DNA leads to inappropriate regulation of proto-oncogenes: normal
cell genes involved, for example, in control of cell division; strong viral promoters over-express proto-
oncogenes); retroviruses (which carry an extra gene with them, a true oncogene which is a mutated proto-
oncogene; by itself, an oncogene can cause cell transformation into cancer); and chronic tissue damage,
with constant cell division for repair over decades; each cell division risks a mistake in DNA replication;
takes decades for cancer to result (example: hepatitis B virus). HPV (human papilloma viruses): cervical
cancer; new vaccine available, standards for use not yet established.
Antiviral drugs: Nucleoside analogs: what are they “analogs” of, how do they work, why are they
selectively toxic? Neuraminidase inhibitors: specifically target influenza virus (Tamiflu). Interferons
(natural proteins of the immune system). Anti-retrovirals: know all 4 categories: nucleoside analogs,
entry inhibitors, non-nucleoside RT inhibitors (which, like nucleoside analogs, target the viral
polymerase, but these affect RT by a different mechanism than competitive inhibition); and protease
inhibitors. These are administered to patients in combinations (HAART; why?). Understand what the
HIV protease does.
Prions. Infectious protein particles, no nucleic acid at all. Mad cow disease. Cannibalism.
Protozoa. Single cell eukaryotes. Giardia (cyst vs trophozoite, how transmitted); Toxoplasma (how
transmitted: role of cats, eating contaminated meat; why the disease is important: unborn babies).
Plasmodium (malaria): Anopheles mosquito is the vector. Basic life cycle: mosquito bite; blood; liver;
erythrocytes; synchronized red cell lysis & fever; gametocytes back to mosquito.
Ch. 16 Innate Immunity
Be able to distinguish between innate (nonspecific) and adaptive (specific) immune defenses. List some
innate defenses against microbial infection: e.g., skin, sweat, coughing, lysozyme, stomach acid. How
does transferrin protect against infection? Blood comes from stem cells in bone marrow. #WBC in blood
increases with infection. Myeloid vs lymphoid lineages. Know key features each leukocyte type (don’t
