Use of single-cycle analysis to study rates and mechanisms of retroviral mutation.

Retroviruses evolve at rapid rates. This allows them to escape immune surveillance, thwarts vaccine development, and leads to rapid emergence of drug-resistant virus. Information regarding the retroviral mutation rates and the underlying mechanisms of mutagenesis will undoubtedly expedite the development of strategies to combat retroviral-mediated diseases. In this review, we discuss how the unique retroviral life cycle can be adapted such that retroviral variation can be studied in a single cycle of replication. By limiting replication to a single cycle, retroviral mutation rates can be directly measured, and the consequences of mutations can be observed. In addition, retroviral recombination rates as well as the nature of primer strand transfer during reverse transcription can be studied using this system. Molecular analysis of the spectrum of mutations arising during a single cycle of virus replication also sheds light on the mechanisms of mutagenesis and retroviral replication.