Genetic characteristics of HPV68 strains detected in Vietnamese women

Abstract

Human papillomavirus (HPV) 68 is one of high - risk HPV genotypes causing cervical cancer in women with a prevalence ranking only after HPV52, 16 and 18. However, the current approved HPV vaccines do not include this genotype. Moreover, data about genetic characteristics of HPV68 is scarce. Therefore, the aims of this study is to analyse genetic characteristics of 12 HPV68 strains isolated from 3078 clinical samples in Hanoi and Ho Chi Minh City by sequencing. Phylogenetic tree based on L1 sequences was constructed for lineage classification (1-10% different in L1 sequences) by maximum likelihood method and SNPs (single nucleotide polymorphisms) were detected in comparison with the prototype. The
results showed lineage C is the predominant subtypes, accounting for 80% samples. Among E6, E7 and L1 genes, L1 gene had the highest SNPs frequency of 8.2% while protein E7 has the highest frequency in amino acid substitution (11.7%). This study reported some SNPs that lead to amino acid substitutions in HPV68 sequences isolated in Vietnam, in which the amino acid substitutions Y18C and Q22E are located at the interaction site between E7 and Rb1 proteins. Further study should be done to reveal the relationship between non-synonymous SNPs and risk of cervical cancer development.