The Human Immunodeficiency Virus, HIV, is a retrovirus with RNA as its genetic material. Researchers posit that the Simian Immunodeficiency Virus (SIV), originating in chimpanzees, was the initial cause of HIV infection in humans.
It is theorized that SIV was transmitted to humans and mutated into HIV when humans in Africa hunted chimpanzees for meat and exposed themselves to the infected blood. The mutation rate in retroviruses, including SIV and HIV, is much higher than it is among DNA viruses.
The most likely explanation for this is that
A. DNA is more chemically stable than RNA
B. Retroviruses like HIV lack replication error-checking mechanisms when copying DNA from RNA, and thus have higher rates of mutation.
C. Retroviral envelopes are able to fuse with host cell membranes, causing spontaneous changes in the viral genome.
D. The action of host cell restriction enzymes can trigger base changes in viral RNA
VerifiedHint: Consider the mechanism of retrovirus replication and the role of reverse transcriptase.
Complete step-by-step Answer: Retroviruses are a type of virus that contains RNA as its genetic material. To replicate, retroviruses must first convert their RNA genome into DNA. This is done using an enzyme called reverse transcriptase. Reverse transcriptase is a very fast enzyme, but it is also very error-prone. This means that it often makes mistakes when copying RNA, which can lead to mutations in the viral genome.
DNA viruses, on the other hand, replicate using DNA polymerases. DNA polymerases are much more accurate enzymes than reverse transcriptase. This is because DNA polymerases have a proofreading function, which allows them to correct any mistakes that they make. As a result, DNA viruses have lower mutation rates than retroviruses.
The high mutation rate of retroviruses has a number of important implications. First, it allows retroviruses to rapidly adapt to new environments and to evade host immune responses. Second, it makes it difficult to develop effective vaccines and treatments for retroviral infections.
For example, HIV is a retrovirus that causes AIDS. HIV has a very high mutation rate, which allows it to rapidly develop resistance to antiretroviral drugs. This is one of the main reasons why it is so difficult to treat HIV infection.
The high mutation rate of retroviruses also makes them a major threat to public health. For example, the Ebola virus is a retrovirus that causes a deadly hemorrhagic fever. The high mutation rate of the Ebola virus makes it difficult to develop a vaccine against the virus.
Overall, the high mutation rate of retroviruses is a major challenge for scientists and public health officials. A better understanding of the mechanisms of retrovirus replication and mutation is essential for developing effective vaccines and treatments for retroviral infections.
Hence the correct answer is Option B
Note: Retroviruses have higher mutation rates than DNA viruses because they use reverse transcriptase, an error-prone enzyme, to copy RNA into DNA. This high mutation rate allows retroviruses to rapidly adapt and evade host immune responses, making them a major challenge for vaccine and treatment development.
