MCM 2-17 DNA Viruses I Flashcards
DNA viruses (except poxvirus) use the host RNA Pol II enzyme to synthesize mRNA. What else is needed for viral mRNA transcription?
A. Cellular DNA fragmentation induced by apoptosis.
B. High concentrations of capsid proteins.
C. RNA-dependent RNA polymerase on cell membranes.
D. Viral and cellular transcription factors that bind to viral gene promoters.
E. Viral or cellular DNA Polymerase and accessory proteins.
D - Viral and cellular TF that bind to viral gene promoters
Which are more genetically stable, DNA viruses or RNA viruses. Why?
DNA polymerases of both host and virus have higher fidelity than RNA polymerases
Genome replication of large DNA viruses occurs in the nucleus and
requires which of the following:
A. Cellular DNA fragmentation induced by apoptosis.
B. High concentrations of capsid proteins.
C. RNA-dependent RNA polymerase.
D. Viral and cellular transcription factors.
E. Viral DNA Polymerase and accessory proteins.
E - Viral DNA polymerase (because they are big like herpes and adenovirus) and accessory proteins
Adenovirus is associated with associated with which of the following diseases? A. Gastroenteritis B.Keratoconjunctivitis C. Pharyngoconjunctival fever D. Pneumonia E. All of the above F.None of the above
E - all
Treatments for adenovirus infections include these options: A. Chemical ablation B. Cidofovir C. Cryotherapy D. Infection control E. Oncotherapy
B - cidovir
The initial phase of human papilloma
virus infection occurs in which cell type
basal epithelium
Treatments for human papilloma virus infection include these options: A. Chemical ablation B. Cryotherapy C. Colposcopy D. VLP vaccine E. All of the above F.None of the above
All of the above
The life cycle of adenovirus follows these steps:
- Attachment – Adenovirus protein binds to cell receptor.
- Entry – Occurs by endocytosis. Acidification of the endosome causes the lysis of the capsid’s fibers, which serve to break open the endosome.
- Uncoating – The capsid traffics to the nucleus and the DNA genome uncoats through the nuclear pore. RNA gets made, exits cytoplasm, gets made into E1A as a transcription factor.
- Transcription – Early on in the life cycle, the viral genes are transcribed into mRNA. As transcription factors are synthesized, transcription can occur at an even greater rate.
- Replication – Viral DNA polymerase becomes available due to transcription, and DNA replication begins.
- Capsid Assembly – Capsid protein genes are transcribed later on after the viral genome has been replicated many times.
- Egression – Virions egress by lysis.
The key features of the DNA virus lifecycle are:
- Transcription and DNA replication occur in the nucleus (exception: poxvirus)
- Host RNA polymerase II transcribes viral mRNA (exception: poxvirus)
- Viral or host DNA polymerase replicates genome
The host RNA pol II as well as host and viral transcription factors recognize…
viral promoters. The availability or lack of the proper host transcription factors will affect a virus’s ability to function in the host. The viral transcription factors are also important; they are key virulence factors and are sometimes essential to a virus’s success.
some viral DNA sequences are recognized by…
DNA polymerase; such viruses do not encode their own DNA polymerase due to their smaller genome sizes, and they need host DNA polymerase to replicate their genome. Larger viruses encode their own DNA polymerases. Recombination does occur within and between genomes in DNA viruses; however, since DNA polymerases have higher fidelity than RDRP, DNA viruses are more genetically stable than RNA viruses.
adenoviruses are enveloped (TF)
F - they are unenveloped.
what can adenovirus infect?
various parts of the body. They can cause respiratory diseases ranging from a bad cold with a fever to laryngitis and pneumonia. They can also cause gastroenteritis, epidemic keratoconjunctivitis, and other diseases outside the respiratory system.
how is adenovirus passed?
aerosols, fecal-oral, contact with contaminated object/people.
Places where a lot of people are brought together and are in physical contact are common outbreak sites (e.g. daycare centers, swimming clubs, and military boot camps).
prevention/treatment of adenovirus
Adenovirus can be prevented with a vaccine, though it is used only for military personnel. Different tests for adenovirus are available depending on the patient sample obtained. Culture assays, antigen detection, PCR, and serological assays are all potentially usable. Currently, the only treatment is cidofovir, which is nephrotoxic and therefore reserved for dire cases.
