Question

Using Myxoma, HIV and influenza as examples provide three reasons why viruses are able to undergo rapid evolution? Use a different virus as an example for each of the three mechanisms and be clear why each of the viruses were chosen to explain that particular mechanism. sion Font family Font size BIUS X2 X Paragraph HCC E 3 DEA Dr C 2m <> 0 IT IT !!! 111

Answer 1

RNA virus mutates faster than the DNA viruses. Single stranded molecules mutate faster than double stranded. For example, single stranded DNA and single stranded RNA mutate faster than their double stranded counter parts. Genome size also has its influence on the rate of mutation.

Influenza has a genome made of -ssRNA. It is a negative strand and single strand. The negative single strand of RNA does not function as the mRNA. So the virus carries its own RNA dependent RNA protein to make its own mRNA. All single stranded RNAs are more prone to mutation as the nucleotides of the single strand are exposed to the surrounding chemicals.

HIV is a retrovirus. Which means it has ssRNA which is used to form DNA with the help of reverse transcriptase enzyme. The reverse transcriptase enzyme can't accurately reverse transcribe RNA in to DNA. This leads to spontaneous mutations.

Myxoma virus has ds DNA genome. The genome is very large. Because fo the size of the genome, chances of the DNA getting copied is difficult. That is why they develop errors and hence mutate during replication.

Polio virus mutates similar to myxoma virus.

Sars Covid mutates like influenza virus as it is also ssRNA virus.

Murine Leukemia viruses are retroviruses causing cancer in mouse host also mutate similar to HIV.