Exam 26: Viruses

________ infects the CD4+ T cells,which are required for normal immunity.

Which of the following is a virus with an icosahedral head,a capsid that contains primarily three proteins,a connecting neck with a collar and long whiskers,a long tail and a complex base plate?

The pneumonia caused by the influenza virus results from the accumulation of fluid and cell debris in the lungs.This occurs during the lysogenic life cycle of the virus.

Nearly all viruses are constructed of

Nucleotide analogs are a class of drugs that are highly effective against many types of viruses.They work by halting the replication of viral genes.They are equally effective at stopping the spread of prion diseases.

An example of an "emerging virus" (a virus in a new host)with a lethality rate in excess of 50% is

Plasma from a sick mouse is filtered across a membrane that has a 200 nm pore size.If the filtrate is still infectious when injected into a healthy mouse,then the pathogen is most likely a(n):

Vibrio cholerae lives in water and gets toxin genes from a virus by phage conversion.The toxin kills the intestinal epithelial cells in the human host,resulting in massive diarrhea.Untreated cholera has about a 50% mortality rate.How do the bacteria benefit?

Which class of drugs would be effective against HIV but not against most other pathogenic viruses?

Phages are viruses that can infect

What kind of pathogen would retain its ability to cause infections after being treated with powerful proteolytic chemicals that would destroy all proteinaceous material?

Retroviruses are unique because they are a combination of RNA and DNA.

An experimental chemical has been shown to selectively cleave phosphodiester bonds.How would this affect a virus?

What is the name for parasitic viral DNA that has been integrated into the chromosome of its bacterial host?

All of the following are diseases caused by viruses except

Once a prophage is present in a bacterial genome,viral genes are reproduced every time the bacterium multiplies.Expression of viral genes,however,is inhibited by a repressor protein.Cell stress can induce the formation of proteases that degrade the repressor.What will result?

A doctor's office has run out of the latest flu vaccine,but many patients are asking for it.One of the nurses finds some vials from last year's batch in a refrigerator.Should they be used?

Virulent viruses multiply within infected cells and eventually

Can a virus be killed?

Viruses are ________ -coated fragments of DNA or RNA.