Human papillomavirus type 16 exists in bacteria isolated from cervical cancer biopsies.

This study investigated the association between infectious microbes and persistent infection with human papillomavirus type 16 (HPV-16) in cervical cancer. Bacterial strains (identified as Enterococcus, Staphylococcus, Bacillus and Corynebacterium, based on their partial 16S rDNA sequence) were HPV-16 positive from 12 out of 14 cervical cancer biopsies. Total DNA was isolated from the four bacterial strains, and HPV-16 genes and genome were detected using polymerase chain reaction (PCR) and Southern blotting. RNA transcripts for HPV-16 E6 and L1 genes were detected in total bacterial RNA samples using reverse transcription-PCR, and HPV-16 L1 protein expression was detected in bacterial cells by Western blotting and immunocolloidal gold electron microscopy. The presence of virus particles in bacterial cells was demonstrated by transmission electron microscopy. The results suggest that bacteria carrying HPV-16 could provide a potential explanation for how infectious microbes contribute to the progression from HPV-16 infection to cervical cancer.