How do viruses replicate and spread? If we want to understand the fundamental characteristics of viruses, so that we can find ways to tackle them, we need to know how viruses replicate and spread. In this module, we are going to look at virus replication and spread and introduce some terms around these concepts.

To be able to study viruses, we need to be able to isolate and then produce viruses using a process from horticulture called propagation. We can then use cells cultivated in mass quantities using laboratory techniques and pass the isolated virus cells through the cultivated cells to study the effects of the virus in a process called passaging. In this module, we will look at the development of propagation and passaging techniques – how these have evolved over time, and how they have impacted the development and production of vaccines.

There was a lot in the media about variants and mutations during the COVID-19 pandemic. We had variants named after where they were first recognised. Then they were given Greek letter identifiers, such as delta and omicron. How important is it to have an understanding of how viruses evolve, and which types of viruses are likely to evolve much quicker than others? What is the impact of mutations on antiviral drug effectiveness? And overall, how are viruses, and the diseases they cause, shaped by mutation, selection and evolution? This week, we will look at virus mutation, their types and consequences, and the evolution of novel viruses through reassortment, recombination, and adaptation.

Conventional virus genetics talks about the range of genotypes, range of phenotypes, stability and quasispecies. Traditional genetic analysis often involves associating observable phenotypes with genotypes, then mapping the mutations causing those genotypes. Mapping normally involves looking at the genetic linkage between known and unknown genetic markers. In this module, we will look at viral genetics - the approaches used in conventional virus genetics, and the limitations of conventional virus genetics.