Poxviruses

Abstract Poxviruses are large, complex DNA viruses that have played several seminal roles in medicine and biological science. Cowpox virus was introduced by Jenner as the first human vaccine in 1796; widespread vaccination with vaccinia virus led to the global eradication of smallpox in 1977, the only human disease to have been eradicated. Smallpox is caused by variola virus, the most infamous poxvirus. Other poxviruses include molluscum contagiosum, which is the only other poxvirus that infects only humans, causing benign skin tumours that may be single or multiple, typically persisting for months before undergoing spontaneous regression. The development of vaccinia virus as an expression vector pioneered the concept of using genetically engineered viruses as live vaccines. Vaccinia virus is also being developed as an oncolytic agent. Poxviruses remain excellent models for studying virus-host interactions and virus immune evasion strategies.