You discover a new virus. It has a single stranded + sense RNA genome. It uses a special enzyme to convert the RNA genome into double stranded DNA. Transcription of mRNA is carried out from the DS DNA template. Which group in the Baltimore classification system would you place this virus into?

Group VI viruses (retroviruses)

Explanation:

Baltimore classified the viruses in different groups on the basis of their mode of replication and the type of genetic material they possess.

In the given question, the species which contains an ssRNA molecule but use DNA as an intermediate molecule to replicate is known as a retrovirus.

The retrovirus uses a special enzyme called reverse transcriptase which synthesizes the DNA from an RNA template. The DNA formed gets integrated into the host genome and gets replicated.

Thus, Group VI viruses are the correct answer.