Use the Following Information When Answering the Corresponding Questions)

Use the following information when answering the corresponding questions) .
It has been shown that there are two distinct variants of the HIV virus Bleul et al. 1997. The HIV coreceptors CXCR4 and CCR differentially regulated on human T- lymphocytes. Proceedings of the National Academy of Science 94:1925- 30) . One virus preferentially infects macrophages and is called M- tropic. The other preferentially infects T cells and is called T- tropic. The M- tropic viruses use CCR5 and CD4 as coreceptors, and the T- tropic viruses use CXCR4 and CD4 as coreceptors. The
M- tropic viruses are found early in HIV infections; the T- tropic viruses are found late in infections, when AIDS symptoms are prevalent. T- tropic viruses are associated with a drastic decrease in T cells. Macrophages go to the site of wounds, where they are used to fight infections. T cells circulate in the body and fight infections at many sites.
-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 labelling of only very long proteins, while longer periods of labelling result in several different short polypeptides. What conclusion is most consistent with the results of the radioactive labelling experiment?

A) The RNA is translated into short polypeptides, which are subsequently assembled into large ones.
B) The large radioactive polypeptides are coded by the host, whereas the short ones are coded for by the virus.
C) The RNA is only translated into a single long polypeptide, which is then cleaved into shorter ones.
D) Host- cell ribosomes only translate the viral code into short polypeptides.