1. The virus you isolated recently from Delaware County is an enveloped RNA viru
ID: 211837 • Letter: 1
Question
1. The virus you isolated recently from Delaware County is an enveloped RNA virus. RNA isolated from this virus is capable of supporting translation in a rabbit reticulocyte cellfree translation system or in any other such system. Further analysis indicates that this virus replication is not inhibited by actinomycin D, a strong inhibitor of DNA-dependent RNA polymerase. Based on this information, discuss the mechanism by which this virus replicates in infected HeLa cells in culture.
2. The virus you isolated recently from Delaware County is a naked icosahedral RNA virus. RNA isolated from this virus is capable of supporting translation in a rabbit reticulocyte cellfree translation system or in any other such system. Further analysis indicates that this virus replication is inhibited if infected cells are incubated with protease inhibitor such as trypsin inhibitor. Based on this information, discuss the mechanism by which this virus replicates in infected cells.
Explanation / Answer
1- There are two types of single-stranded virus.
A- Positive-strand RNA virus - This virus is same as mRNA which can be directly translated into protein.
B- Negative-strand RNA virus- This virus has antisense-RNA which need to be converted into positive-strand RNA to proceed translation same as mRNA which can be directly translated into protein.
RNA virus replicates inside the host cell by the protein which is encoded by the virus genome itself. This protein is called as RNA-dependent RNA polymerase which uses RNA as the template and replicates the viral genome.
Since the RNA isolated from the virus is capable of translation in a rabbit reticulocyte cellfree translation system. So virus the genome of the virus is Positive-strand RNA.
2- Generally virus translate its whole genome and the translated protein is cleaved by the virus protein into functional enzymes. These enzymes help in viral replication and viral infection to the other cells as well
Given that, upon treatment with the protease inhibitor, the virus cannot replicate which means that RNA virus is producing the protein which is being cleaved by the proteases into functional enzyme which helps in the replication of the virus. The virus is dependent on the viral protein for its replication.
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