Virology Flashcards
Infectious, obligate intracellular parasite
Virus
viral particle
virion
Can a virus have both DNA and RNA?
no (one or the other)
What are virions composed of?
-RNA or DNA
-protein coat
-Envelope
virus size?
Very small
-Pass 0.2 µm filters
If the cell is lysed to spread the virus, it will not have what?
an envelope
True or false:
Viruses lack the complex energy-generating and biosynthetic systems necessary for
independent existence.
True
what are the simplest biologically active agents?
-viroids
-prions
-Single small molecule of non-coding RNA
-Plant pathogens
Viroids
Single protein molecules capable of infection
Prions
HIV —> enzyme —-> ________ transcriptase (RNA to DNA)
reverse
HIV infects what type of cells?
CD4
Infectious progeny virus particles, called _________ , are formed by de novo self-assembly from newly synthesized components.
Virions
What is the vehicle for transmission of the viral genome to the next host cell or organism, where its disassembly initiates the next infectious cycle.
-A progeny virion assembled during the infectious cycle
How can viruses be visualized?
-electron microscope
-x-ray
What is the size of viruses?
10^2 nanometers
Steps of viral infectious cycle?
-Attachment
-Penetration
-Uncoating (envelope)
-Replication: RNA –> mRNA –> more RNA
–> DNA —> mRNA
-Maturation (Assembly)
-Release (Death of cell = apoptosis)
What does ICTV stand for?
International Committee on Taxonomy of Viruses
Organization tasked with viral nomenclature
International Committee on Taxonomy of Viruses (ICTV)
virus taxonomy:
virus order –>
-virales
virus taxonomy:
subfamily —>
-virinae
virus taxonomy:
genus —->
-virus
viruses are not classified beyond _________.
species
-subspecies-level assignments or “types” are not recognized by the ICTV
What are the two systems used for viral taxonomy?
-International Committee on Taxonomy of Viruses (ICTV)
-Baltimore classification
What is Baltimore classification based on?
7 groups based on nucleic acid (DNA, RNA), strandedness (single, double), sense (+,-), method of replication.
BC for Adeno, Herpes?
dsDNA -1
BC for Parvo?
ssDNA - 2
BC for Reo?
dsRNA - 3
BC for Picorna?
(+) ssRNA - 4
BC for Orthomyxo?
(-) ssRNA - 5
BC for Retro?
ssRNA-RT - 6
BC for Hepadna?
dsDNA-RT - 7
***H2A2P2P2y (HAPPy) —>
DNA viruses
Hepadnaviridae
Herpesviridae
Adenoviridae
Anelloviridae
Parvoviridae
Papillomaviridae
Polyomaviridae
Poxviridae
-Usually asymptomatic but can be acute or chronic; self-limiting or fatal
-Liver damage; may require transplant
-Fatal = co-infection with hepatitis D
Hepadnavirus (Hep B)
*DNA virus
What are the serology markers associated with HBV that can be tested?
-Contains surface antigens (HBsAG)
-Core antigen (HBcAg)
-Another core: (HBeAg)
-Also test for HbsAb, HbeAb
What are the two HBV serology markers that come from the envelope?
HBsAG and HBeAG
What HBV serology markers indicate an infected state?
HBsAG
-also HBeAG
What happens during the “window period” for HBV?
-conversion of surface antigen markers to surface antibody markers
-isolated Anti-HBc following acute infection (see chart on slide 14)*
Anti-HBs is associated with…
-resolved HBV infection (will still have total anti-HBc) or,
-HBV vaccination
Serologic Profiles - HBV:
Early acute hepatitis B…
HBsAg
(maybe HBeAg)
Serologic Profiles - HBV:
Acute or chronic HBV…
-HBsAG
-HBeAg
-HBcAb
Serologic Profiles - HBV:
Chronic HBV carrier…
-HBsAg
-HBeAg
-HBcAb
Serologic Profiles - HBV:
Recovery with immunity…
-HBsAb
-HBeAb
-HBcAb
Serologic Profiles - HBV:
Distant infection or vaccine…
-HBsAb
What is the first HBV marker after exposure?
HBsAg
*always indicates current infection
True or false?
Multiple blood infections can cause both HBsAg and HBeAb.
True, but normally not possible
HAV, HCV, and HEV are DNA or RNA viruses?
are they related to each other?
-RNA
No, unrelated
-Often children (daycare settings)
-Occasional epidemics
-Person-to-person
-Acute onset; may take months to recover
-Shed in large numbers in feces
-Low mortality/ no liver damage
-Vaccine available
-Routine vaccination recommended for children
HAV
What are the most frequent food sources of HAV?
-Water, shellfish, and salads are the most frequent sources
-Contamination of foods by infected workers in food processing plants and restaurants is common.
How is HCV transmitted?
blood and body fluids
What was the old name for HCV?***
nonA, nonB
What virus was predicted and sequenced before being viewed with EM?
HCV
True or false:
There is a vaccine available for HCV.
False
New drugs available for HCV, per WHO antiviral drugs can cure ____% of persons-reducing risks of cirrhosis and cancer
95
Long term effects of Hepatitis C:
~___% spontaneously clear their infection within 6 months without treatment
~___% develop chronic HCV
30, 70
Of the 70% of people who develop chronic HCV,
-____% cirrhosis within 20 years
-_____% increased risk of liver cancer (yearly)
-____% increased risk of hepatic decompensation (yearly)
-15-30
-1-5
-3-6
What are the different Herpes virus types?
HSV-1, HSV-2, VZV, EBV, CMV
____ % of American adults have been infected with HSV-1; ____ % have HSV-2 infections
Most are asymptomatic
Oral, genital, neonatal, encephalitis, ocular.
80
20
-Latent viral genomes in peripheral nervous system
-Infect epithelial cells
-Multi-nucleated giant cells at the base of lesion
HSV
How are HSV viruses released?
Lyse, releasing clear fluid containing viruses
What are the antivirals for HSV?
acyclovir, valacyclovir, and foscarnet (cases where acyclovir resistance suspected)
-Most people have been exposed.
-Vast majority asymptomatic, but can recur in compromised patients
-May be life-threatening to immunocompromised, transplant patients, and fetuses.
CMV
CMV:
1 in ____ have been infected by age five ___ % of adults by age 40 have been infected with CMV
3, 50%
How long does CMV stay in the body?
stays in the body for life and can reactivate
What is a distinguishing feature of CMV?
It can be found in almost any part of the body. Most viruses have more specific targets.
Examples: can detect in blood, eye (CMV retinitis), pneumonia, gastrointestinal tract, brain
What type of virus is Epstein-Barr Virus (EBV)?
Herpesviridae
-dsDNA
How is EBV spread?
Spread via saliva
Infects oropharyngeal epithelial cells and then enters B-cells
~1 in 10^6 B cells harbors EBV
EBV:
Latent infection of primary B-cells: Virus infects non-dividing B cells with very high efficiency, then triggers these cells to proliferate and sustains their proliferation, resulting in cellular ____________.
immortalization
Most EBV-associated disease is due to __________ infected cells.
latently
True or false:
Once infected with Epstein-Barr virus, a lifelong carrier state develops whereby a low grade infection is kept in check by the immune defenses.
True
EBV:
Low grade virus replication and shedding can be demonstrated in the epithelial cells of the _________ of all seropositive individuals.
pharynx
EBV is able to immortalize ____-lymphocytes in vitro and in vivo.
B
What are the diseases associated with Epstein-Barr Virus (EBV)?
-Infectious Mononucleosis
-Burkitt’s lymphoma
-Nasopharyngeal carcinoma
-Lymphoproliferative disease and lymphoma in the
immunosuppressed
-Oral leukoplakia in AIDS patients
-Chronic interstitial pneumonitis in AIDS patients
EBV (Epstein Barr Virus):
-Most adults Ab pos.
-Symptoms last a few weeks; malaise may be prolonged; young adults
Infectious mononucleosis
EBV (Epstein Barr Virus):
Rare highly aggressive non-Hodgkins lymphoma
Usually fata if not treated rapidly
Burkitt’s lymphoma/B-cell lymphoma
What is the test for Mono?
heterophile antibodies (Monospot test)
Test that uses horse red blood cells
-agglutination = positive test
-some tests replace RBCs with latex beads
Monospot test (EBV testing)
Chickenpox =
varicella