Our travel through the viral replication cycle ends with a discussion of how virus particles are built. Viruses are assembled by a sequential or concerted process, usually by first making sub-assemblies. Viral nucleic acids are incorporated preferentially by packaging sequences on viral genomes. An envelope is acquired during the budding process when the ESCRT pathway of the cell is usurped. And non-enveloped viruses leave cells by breaking them open, or by surreptitiously acquiring an envelope.
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.