The distribution and common amino acid polymorphisms of human papillomavirus (HPV)-31 variants in 2700 women from Northern China.

To investigate the distribution of Human papillomavirus (HPV)-31 A, B and C variants as well as the common amino acid polymorphisms in Chinese women, all 14 HPV-31 positive cervical exfoliated cell specimens identified from a descriptive study including ∼2700 women from Northern China were analyzed. HPV-31 positive specimens were identified by Mass Spectrometry and the fragments of partial Long Control Region, E6 and E7 were amplified and directly sequenced or cloned into vector and then sequenced to confirm the variant information. HPV-31 prevalence in Northern Chinese female population was 0.52%. Six different sequences represented all 14 isolates, and these isolates were subsequently classified into variant lineage A (9), B (0) and C (5) by phylogenetic analysis. Five common amino acid polymorphism sites (2 in E6 and 3 in E7) and a novel non-synonymous mutation were detected in the current study. Our investigation suggested that HPV-31 was much less detected in Chinese women population than that in western countries. A and C variants were commonly detected while B variants were rarely detected in this population.