Retroid viruses have the enzyme reverse transcriptase as part of their replication cycles. This enzyme, whose discovery by Temin and Baltimore shattered the dogma about the information flow in biological systems, produces DNA from RNA. In this lecture we discuss the discovery of reverse transcriptase in the context of RNA tumor viruses, the mechanism of reverse transcription and integration, and its role in the cycles of retroviruses and hepatitis B virus. We also consider the origin and functions of retroelements in the genome, mobile sequences that move about through the action of reverse transcriptase.
In this course, Prof. Vincent Racaniello gives 26 video lectures on Virology. The basic thesis of the course is that all viruses adopt a common strategy. The strategy is simple:
1. Viral genomes are contained in metastable particles. 2. Genomes encode gene products that promote an infectious cycle (mechanisms for genomes to enter cells, replicate, and exit in particles). 3. Infection patterns range from benign to lethal; infections can overcome or co-exist with host defenses.
Despite the apparent simplicity, the tactics evolved by particular virus families to survive and prosper are remarkable. This rich set of solutions to common problems in host/parasite interactions provides significant insight and powerful research tools. Virology has enabled a more detailed understanding of the structure and function of molecules, cells and organisms and has provided fundamental understanding of disease and virus evolution.
The course will emphasize the common reactions that must be completed by all viruses for successful reproduction within a host cell and survival and spread within a host population. The molecular basis of alternative reproductive cycles, the interactions of viruses with host organisms, and how these lead to disease are presented with examples drawn from a set of representative animal and human viruses, although selected bacterial viruses will be discussed.