Virology, Emerging Diseases & vaccines

Viral Genetics, Evolution and Dynamics

Viral genetics is the study of the mechanisms of heritable information in viruses, including genome structure, replication and genetic change. Viruses have been engineered as vectors for gene expression, vaccine development, and gene therapy. Viral genomes encode gene products that modulate host defences, including the immune response, an elaborate system that evolved in large part to protect us against invading microorganisms like viruses. Ideally, pathogens are cleared by immune defences with minimum damage to the host. However, in the process, the immune defences themselves can also cause damage (immunopathology). Viral evolution refers to the heritable genetic changes that a virus accumulates during its life time, which can arise from adaptations in response to environmental changes or the immune response of the host. Because of their short generation times and large population sizes, viruses can evolve rapidly. RNA viruses have high mutation rates that allow especially fast evolution. An example is the evolution of drug resistance in HIV.  Viruses are believed to have played important roles in the evolution of cellular organisms. Though viruses aren’t technically living – they need a host organism in order to reproduce – they are subject to evolutionary pressures. The recent development of potent antiviral drugs not only has raised hopes for effective treatment of infections with HIV or the hepatitis B virus, but also has led to important quantitative insights into viral dynamics in vivo. Viral dynamics include virus population dynamics, the role of the immune system in limiting virus abundance, the dynamics of viral drug resistance.