SV40 infection of human cells results in both transformation and lytic infection. We have used origin-defective viral mutants which are unable to replicate in permissive cells to help analysis of transformation. Expression of large T antigen (T ag) and small t antigen results in the altered growth phenotypes characteristic of transformation in other species. Human diploid fibroblasts (HF) have a limited lifespan and undergo senescence; T ag results in extension of lifespan but only in rare cases are the cells capable of continuous growth and are immortal.
Cancer Epidemiology, Biomarkers & Prevention: A Publication of the American Association for Cancer Research, Cosponsored by the American Society of Preventive Oncology
Research from the past several years has definitively shown intermediate and high risk-type human papillomavirus (HPV) infection to play a significant role in cervical carcinogenesis. Persistent compared with intermittent infection appears to confer an elevated risk, and cofactors may be necessary to allow the virus to progress to cervical cancer.