The infectious cycle is the name for the entire sequence of events from virus binding to cells to release of new progeny virus particles. In this lecture we define the infectious cycle, and discuss how to study it. We cover assay of infectious virus particles by plaque assay, multiplicity of infection, and the particle to pfu ratio. We also discuss physical methods for detecting viruses including hemagglutination, polymerase chain reaction, and deep, high-throughput sequencing.
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.