Final answer:
The replication of a negative-sense RNA genome requires reverse transcription performed by the RNA-dependent RNA polymerase enzyme, followed by transcription and translation to produce viral proteins. Positive DNA viruses directly undergo replication and transcription. Retroviruses uniquely use reverse transcriptase to integrate into the host genome.
Step-by-step explanation:
The steps required for the replication of a negative-sense RNA (Ribonucleic Acid) genome versus a positive DNA (Deoxyribonucleic Acid) are different due to the varied processes involved in each case. When dealing with the replication of a negative-sense RNA virus, it is crucial that reverse transcription takes place first. In this instance, reverse transcription is imperative because the -ssRNA (negative-sense single-strand RNA) must be converted into +ssRNA (positive-sense single-strand RNA) by an enzyme the virus brings along, called RNA-dependent RNA polymerase (RdRP). Once this is achieved, the newly formed +ssRNA can be used for the production of viral proteins through transcription and translation.
On the other hand, for positive DNA viruses, the process involves replication and transcription. Replication allows for the DNA to be copied within the host cell, whereas transcription uses the replicated DNA to create mRNA, which then undergoes translation to form various proteins needed for the virus to assemble and propagate. It is worth noting that certain RNA viruses, like retroviruses, employ a unique mechanism via reverse transcriptase to convert RNA into DNA, which is then integrated into the host's genome before being transcribed into mRNA.