In rare instances, the live virus in oral polio vaccines can mutate and become infectious, causing new outbreaks.

Scientists spent five years reconstructing what is now the oldest HIV-1 genome yet recovered.

Tiny insects carry the tomato spotted wilt virus, which causes infected plants to develop discolored ring-shape blotches.

Analyses of more than 300 ancient human genomes show that Hepatitis B virus has infected humans for at least 4,500 years and has much older origins than modern viral genomes would suggest.

Using epidemiological and laboratory data, scientists have mapped out a sequence of mutations through which the attenuated oral polio vaccine reverts to a virulent virus.

Genetic diversity helped avian influenza A viruses make the leap from birds to humans, researchers report.

Tracking the genetic diversity and evolution of rhinoviruses can lead to a better understanding of viral evolution, the common cold, and more dangerous infections.

The National Institutes of Health reveals a controversial plan to regulate the funding of H5N1 research.

The poxvirus stockpiles genes when it needs to adapt.