Exam 33: Viruses

You just discovered a new virus. This virus infects heart muscle, where it causes inflammation, and has a very high mutation rate. Which of the following is the best strategy for finding a treatment for this virus?

What would the result be if a drug that blocks the action of RNA polymerase was introduced into a virus-infected organism?

To make a vaccine against mumps, measles, or rabies, which type of viruses would be useful?

HIV is inactivated in the laboratory after a few minutes of sitting at room temperature, but the flu virus is still active after sitting for several hours. What are the practical consequences of these findings?

Which of the three types of viruses shown in the accompanying figure has a capsid?

A bacterium is infected with an experimentally constructed bacteriophage composed of the T2 phage protein coat and T4 phage DNA. The new phages produced would have ________.

Which of the following is characteristic of the lytic cycle?

Poliovirus is an RNA virus of the picornavirus group, which uses its RNA as mRNA. At its 5' end, the RNA genome has a viral protein (VPg) instead of a 5' cap. This is followed by a nontranslated leader sequence, and then a single long protein-coding region (~7000 nucleotides), followed by a poly-A tail. Observations were made that used radioactive amino acid analogues. Short period use of the radioactive amino acids results in labeling of only very long proteins, while longer periods of labeling result in several different short polypeptides. What conclusion is most consistent with the results of the radioactive labeling experiment?

Effective antiviral drugs are usually associated with which of the following properties?

A population of viruses with similar characteristics is called a ________.

It is believed that HIV has passed from chimps to humans more than once. This suggests that animal-to-human viral transmissions may be more common than previously thought. What is the best evidence in support of the conclusion that HIV made the chimp-to-human leap more than once?

Viral envelopes can best be analyzed with which of the following techniques?

What is the function of reverse transcriptase in retroviruses?

Mimivirus contains some of the genes required for protein synthesis. This is cited as support for which hypothesis about the origins of viruses?

Which of the following human diseases is caused by a virus that requires reverse transcriptase to transcribe its genome inside the host cell?

Which of the following can be effective in preventing the onset of viral infection in humans?

Use the following information to answer the question(s) below. The herpes viruses are important enveloped DNA viruses that cause disease in vertebrates and in some invertebrates such as oysters. Some of the human forms are herpes simplex virus (HSV) types I and II, causing facial and genital lesions, and the varicella zoster virus (VSV), causing chicken pox and shingles. Each of these three actively infects nervous tissue. Primary infections are fairly mild, but the virus is not then cleared from the host; rather, viral genomes are maintained in cells in a latent phase. The virus can later reactivate, replicate again, and infect others. -In electron micrographs of HSV infection, it can be seen that the intact virus initially reacts with cell-surface proteoglycans, then with specific receptors. This is later followed by viral capsids docking with nuclear pores. Afterward, the capsids go from being full to being "empty." Which of the following best fits these observations?

You are a physician and you suspect your patient has a viral infection that has never been seen in humans. The infection is localized in the cells along the lining of the small intestine. The cells in this area are regularly sloughed off and replaced with new cells; that is, these cells are constantly dividing. When you isolate this new virus and incubate it in culture, you discover that it does not replicate well in cultures that have slowly dividing cells, but it does much more damage in cultures that have actively dividing cells. What do these findings suggest about this new virus?

A biologist develops a new drug that seems to dramatically slow the onset of symptoms resulting from HIV infection. Close monitoring of HIV-infected cells reveals that the viral proteins are in the form of long polyproteins. The biologist most likely developed a ________.

Which of the following viruses would most likely have reverse transcriptase?