Intracellular surveillance of persisting viral infections. Human genital cancer results from deficient cellular control of papillomavirus gene expression.

A model is proposed to explain basic features of viral oncogenesis in man such as the long interval between primary infection and tumour appearance, the small number of infected individuals in whom cancer develops, and the monoclonality of the tumours. These cancers are viewed as the result of failing intracellular control of persisting viral genomes in proliferating cells. This type of intracellular surveillance is regarded as a defence mechanism ancestrally older than immunological control, protecting the host at cellular level against potentially lethal effects of coevolving persisting viruses.