Niche adaptation and viral transmission of human papillomaviruses from archaic hominins to modern humans
Epidemiologic studies have demonstrated that persistent infection of select oncogenic human papillomaviruses (HPVs) is the main cause of cervix precancer and cancer. Nevertheless, our knowledge of the underlying evolutionary mechanisms driving the divergence and emergence of viral oncogenicity in specific types of HPVs is incomplete. To better understand the molecular evolution of oncogenic HPVs, we isolated viruses from non-human primates, evaluated papillomavirus molecular clock models, and estimated the divergence times of HPV16 and other HPV type variants from their most recent common ancestors. Primate PV-host tissue tropisms indicated niche adaptation of viruses to host ecosystems as the first stage of the evolution of oncogenic HPVs. The data also provided evidence of ancient codivergence of HPV variants with archaic hominins and recent viral transmission from Neanderthals to modern non-African humans through sexual intercourse. Understanding the evolution of papillomaviruses should provide important biological insights and suggest mechanisms underlying HPV-induced cervical cancer, since niche adaptation rather than oncogenicity drives viral fitness.