Vincent, Alan, and Kathy reveal how a retrovirus in the human genome keeps embryonic stem cells in a pluripotent state, from where they can differentiate into all cells of the body.

Vincent, Alan, Dickson and Rich answer listener questions about XMRV, yellow fever vaccine, virus-like particles, West Nile virus, amyotrophic lateral sclerosis and human endogenous retroviruses, multiplicity of infection, and how to make a poxvirus.

Vincent, Alan, and Rich answer listener questions about lab procedures, prokaryotes, endogenous retroviruses, the iPad and teaching, prions, mimivirus, splitting water with viruses, and the polio outbreak in Tajikistan.

Vincent, Dickson, Alan, Rich and Welkin discuss the nature, origin, and evolution of endogenous retroviruses (ERVs), and the recent finding of endogenous filovirus genomes in mammals.