Microbiology - Virology (2) Flashcards
1
Q
Influenza viruses
- Properties
- Vaccine
A
- Properties
- Orthomyxoviruses.
- Enveloped, (-) ssRNA viruses with 8-segment genome.
- Contain hemagglutinin (promotes viral entry) and neuraminidase (promotes progeny virion release) antigens.
- Patients at risk for fatal bacterial superinfection.
- Rapid genetic changes.
- Vaccine
- Reformulated vaccine (“the flu shot”) containing the viral strains most likely to appear during the flu season.
- Killed viral vaccine is most frequently used.
- Live, attenuated (temperature-sensitive mutant) vaccine that replicates in the nose but not in the lung, administered intranasally.
2
Q
Genetic shift / antigenic shifts vs. genetic drift
- Genetic shift / antigenic shifts
- Genetic drift
A
- Genetic shift / antigenic shifts
- Causes pandemics.
- Reassortment of viral genome
- Segments undergo high-frequency recombination, such as when human flu A virus recombines with swine flu A virus.
- Genetic drift
- Causes epidemics.
- Minor (antigenic drift) changes based on random mutation.
- Sudden shift is more deadly than gradual drift.
3
Q
Rubella virus
- Properties
- Causes…
A
- Properties
- A togavirus.
- Causes…
- Causes rubella, once known as German (3-day) measles.
- Fever, postauricular and other lymphadenopathy, arthralgias, and fine rash [A].
- Causes mild disease in children but serious congenital disease (a ToRCHeS infection).
- Congenital rubella findings include “blueberry muffin” appearance, indicative of extramedullary hematopoiesis [B].
- Causes rubella, once known as German (3-day) measles.
4
Q
Paramyxoviruses
- Causes…
- Properties
- Prevention
A
- Causes…
- Paramyxoviruses cause disease in children.
- They include those that cause parainfluenza (croup: seal-like barking cough), mumps, and measles as well as RSV, which causes respiratory tract infection (bronchiolitis, pneumonia) in infants.
- Properties
- All contain surface F (fusion) protein, which causes respiratory epithelial cells to fuse and form multinucleated cells.
- Prevention
- Palivizumab (monoclonal antibody against F protein) prevents pneumonia caused by RSV infection in premature infants.
5
Q
Measles virus
- Properties
- Causes…
- Prevention
A
- Properties
- A paramyxovirus that causes measles.
- Causes…
- Koplik spots [A] and descending maculopapular rash [B] are characteristic.
- SSPE (subacute sclerosing panencephalitis, occurring years later), encephalitis (1:2000), and giant cell pneumonia (rarely, in immunosuppressed) are possible sequelae.
-
3 C’s of measles:
- Cough
- Coryza
- Conjunctivitis
- Prevention
- Vitamin A used to prevent severe exfoliative dermatitis in malnourished children.
6
Q
Mumps virus
- Properties
- Causes…
A
- Properties
- A paramyxovirus.
- Causes…
- Symptoms: Parotitis [A], Orchitis (inflammation of testes), and aseptic Meningitis.
- Mumps makes your parotid glands and testes as big as POM-poms.
- Can cause sterility (especially after puberty).
- Symptoms: Parotitis [A], Orchitis (inflammation of testes), and aseptic Meningitis.
7
Q
Rabies virus
- Properties
- Causes…
- Treatment
A
- Properties
- Bullet-shaped virus [A].
- Negri bodies [B] commonly found in Purkinje cells of cerebellum and in hippocampal neurons.
- More commonly from bat, raccoon, and skunk bites than from dog bites in the United States.
- Causes…
- Rabies has long incubation period (weeks to months) before symptom onset.
- Progression of disease: fever, malaise –> agitation, photophobia, hydrophobia –> paralysis, coma –> death.
- Travels to the CNS by migrating in a retrograde fashion up nerve axons.
- Treatment
- Postexposure treatment is wound cleansing and vaccination ± rabies immune globulin.
8
Q
HAV
- Virus
- Transmission
- Carrier?
- Incubation
- HCC risk?
- Notes
A
- Virus
- RNA picornavirus
- Transmission
- Fecal-oral
- Carrier?
- No
- Incubation
- Short (weeks)
- HCC risk?
- No
- Notes
- Asymptomatic (usually), Acute, Alone (no carriers)
- HAV and HEV are fecal-oral
- The vowels hit your bowels.
- Naked viruses do not rely on an envelope so they are not destroyed by the gut.
9
Q
HBV
- Virus
- Transmission
- Carrier?
- Incubation
- HCC risk?
- Notes
A
- Virus
- DNA hepadnavirus
- Transmission
- Parenteral, sexual, maternalfetal
- Carrier?
- Yes
- Incubation
- Long (months)
- HCC risk?
- Yes: integrates into host genome, acts as oncogene
- Notes
- In HBV, the DNA polymerase has both DNA- and RNA-dependent activities.
- Upon entry into the nucleus, the polymerase functions to complete the partial dsDNA.
- The host RNA polymerase transcribes mRNA from viral DNA to make viral proteins.
- The DNA polymerase then reverse transcribes viral RNA to DNA, which helps form new viral particles
10
Q
HCV
- Virus
- Transmission
- Carrier?
- Incubation
- HCC risk?
- Notes
A
- Virus
- RNA flavivirus
- Transmission
- Primarily blood (IVDU, posttransfusion)
- Carrier?
- Yes
- Incubation
- Long
- HCC risk?
- Yes: from chronic inflammation
- Notes
- Chronic, Cirrhosis, Carcinoma, Carrier
11
Q
HDV
- Virus
- Transmission
- Carrier?
- Incubation
- HCC risk?
- Notes
A
- Virus
- RNA delta virus
- Transmission
- Parenteral, sexual, maternalfetal
- Carrier?
- Yes
- Incubation
- Superinfection (HDV after HBV)—short
- Co-infection (HDV with HBV)—long
- HCC risk?
- Yes
- Notes
- Defective virus Dependent on HBV
- Superinfection –> decreased prognosis
12
Q
HEV
- Virus
- Transmission
- Carrier?
- Incubation
- HCC risk?
- Notes
A
- Virus
- RNA hepevirus
- Transmission
- Fecal-oral, especially with waterborne epidemics
- Carrier?
- No
- Incubation
- Short
- HCC risk?
- No
- Notes
- High mortality in pregnant women
- Enteric, Expectant mothers, Epidemic
- HAV and HEV are fecal-oral:
- The vowels hit your bowels.
- Naked viruses do not rely on an envelope so they are not destroyed by the gut.
13
Q
Signs and symptoms of all hepatitis viruses
A
- Episodes of fever
- Jaundice
- Increased ALT and AST.
14
Q
Hepatitis serologic markers (166)
- Anti-HAV (IgM)
- Anti-HAV (IgG)
- HBsAg
- Anti-HBs
- HBcAg
- Anti-HBc
- HBeAg
- Anti-HBe
A
- Anti-HAV (IgM)
- IgM antibody to HAV
- Best test to detect active hepatitis A.
- Anti-HAV (IgG)
- IgG antibody indicates prior HAV infection and/or prior vaccination
- Protects against reinfection.
- HBsAg
- Antigen found on surface of HBV
- Indicates hepatitis B infection.
- Anti-HBs
- Antibody to HBsAg
- Indicates immunity to hepatitis B.
- HBcAg
- Antigen associated with core of HBV.
- Anti-HBc
- Antibody to HBcAg
- IgM = acute/recent infection
- IgG = prior exposure or chronic infection.
- Positive during window period.
- Antibody to HBcAg
- HBeAg
- A second, different antigenic determinant in the HBV core.
- Indicates active viral replication and therefore high transmissibility.
- Anti-HBe
- Antibody to HBeAg
- Indicates low transmissibility.
15
Q
Hepatitis serologic markers (166)
- For each
- HBsAg?
- Anti-HBs?
- HBeAg?
- Anti-HBe?
- Anti-HBc IgM/IgG?
- Acute HBV
- Window
- Chronic HBV (high infectivity)
- Chronic HBV (low infectivity)
- Recovery
- Immunized
A
- Acute HBV
- HBsAg (+)
- HBeAg (+)
- Anti-HBc IgM
- Window
- Anti-HBe (+)
- Anti-HBc IgM
- Chronic HBV (high infectivity)
- HBsAg (+)
- HBeAg (+)
- Anti-HBc IgG
- Chronic HBV (low infectivity)
- HBsAg (+)
- Anti-HBe (+)
- Anti-HBc IgG
- Recovery
- Anti-HBs (+)
- Anti-HBe (+)
- Anti-HBc IgG
- Immunized
- Anti-HBs (+)
16
Q
HIV
- Genome
- The 3 structural genes (protein coded for)
- Mechanism
- Homozygous vs. heterozygous
A
- Genome
- Diploid genome (2 molecules of RNA).
- The 3 structural genes (protein coded for)
- env (gp120 and gp41)
- Formed from cleavage of gp160 to form envelope glycoproteins.
- gp120—attachment to host CD4+ T cell.
- gp41—fusion and entry.
- gag (p24)—capsid protein.
- pol—reverse transcriptase, aspartate protease, integrase.
- env (gp120 and gp41)
- Mechanism
- Reverse transcriptase synthesizes dsDNA from RNA
- dsDNA integrates into host genome.
- Virus…
- binds CCR5 (early) or CXCR4 (late) co-receptor and CD4 on T cells
- binds CCR5 and CD4 on macrophages.
- Homozygous vs. heterozygous
- Homozygous CCR5 mutation = immunity.
- Heterozygous CCR5 mutation = slower course.
18
Q
Time course of untreated HIV infection
A
-
Four stages of untreated infection:
- Flu-like (acute)
- Feeling fine (latent)
- Falling count
- Final crisis
- During latent phase, virus replicates in lymph nodes.
