[HBV genotyping based on key epitopes of PreS1 antigen and its correlation with genotyping by full-length PreS1 sequencing].

Objective: The aim was to investigate the genotype distribution of two major epitopes of large surface protein (PreS1) of hepatitis B in Chinese patients and to explore the association between the genotypes of these two epitopes, and to determine whether PreS1 full-length genotype could be revealed according to the polypeptide sequence of key epitopes. Methods: HBV DNA was extracted from the serum of patients for PCR amplification. 278 samples amplified successfully were sequenced and compared with the known HBV sequences in Genbank to determine the two key epitopes of HBV PreS1 genotype (amino acid epitope 21-47 and 94-117, abbreviated as P21 and P94) and PreS1 full-length genotypes. The correlation among three genotyping approaches was analyzed by Cohen's kappa coefficient to verify the consistency between the key-epitope genotyping and the full-length preS1 genotyping. Results: 232 samples were successfully sequenced. The genotyping based on the kind of P21 epitope protein sequence, 201 cases for genotype C, 23 cases for genotype B and 8 cases for uncertain genotypes and genotyping based on the form of P94 epitope protein sequence, 199 cases for genotype C, 25 cases for genotype B and 8 cases for indeterminate genotypes. Lastly, the genotyping based on sequence of the full-length PreS1 sequence, 207 and 25 cases for genotype C and B. P21 or P94 epitope genotyping and PreS1 full length genotyping were highly consistent, respectively, 96.55% and 96.12%, and the two epitopes (P21and P94) genotyping have parallel consistency (93.10%). Conclusion: In this study, an innovatively genotyping method based on the amino acid sequence of key epitopes was proposed. The genotypes of HBV in china were mainly B and C genotypes, and the genotypes of key conserved epitopes of HBV PreS1 were highly consistent with the full-length genotyping ( > 96%). Moreover, genotyping with one or two key epitopes can be used in place of the full-length genotyping.