Gene characterization of human rotavirus Jinzhou strains VP4 and VP7 during 2018 and 2020

Abstract:

[Background] Human rotavirus group A (RVA) is the main pathogen of gastroenteritis in infants and important cause of infant death in developing countries. There are no specific drugs until now and vaccines are the only feasible method to prevent infection. As outer capsid proteins VP7 and VP4 are the main targets of rotavirus vaccine, it is necessary to strengthen molecular epidemiological surveillance of local clinical circulating RVA strains against these genes. [Objective] To identify VP7 and VP4 genotypes and analyze their sequence characterization of RVA circulating strains in Jinzhou. [Methods] The fecal samples of infants suffered from RVA infection diarrhea in Jinzhou during 2018?2020 were collected and viral RNA were extracted. VP7 and VP4 gene fragments were amplified by RT-PCR and PCR products were sequenced. Seven RVA strains VP7 and VP4 genes were obtained. The sequencing results were analyzed by genotyping using online tool RotaC V2.0. Phylogenetic and amino acid sequence alignments analysis compared to clinical epidemic strains and vaccine strains were carried out with BLAST, DNAstar, Mega X, Bioedit. [Results] The genotyping results showed that 7 Jinzhou strains in this study was G9P[8]. Phylogenetic analysis confirmed that VP7 and VP4 belonged to lineages G9-Ⅵ and P[8]-3, and nucleotide sequence identity were 99.32%?100% and 99.41%?100%, respectively. There were 4 and 3 amino acid substitutions in the antigen epitope regions 7-1a, 7-1b, 7-2 when JZ strains VP7 were compared with vaccine strains Rotavac and Rotasiil VP7. The amino acid sequences of JZ strains VP4 were compared with vaccine strains Rotarix and RotaTeq VP4. Seven and four amino acid substitution sites located in the antigen epitope regions 8-1, 8-3 were found. [Conclusion] Seven G9P[8] RVA strains were detected in Jinzhou, Liaoning province from 2018 to 2020. The identity of VP7 and VP4 sequences was higher than 99%. G9P[8] was probably one of the main epidemic genotypes of infantile rotavirus diarrhea in Jinzhou, Liaoning province in 2018?2020. Compared to the same genotypic vaccines strains, amino acids variations located in VP7 and VP4 epitope regions of JZ strains are significant for understanding immune escape mechanisms of wild RVA strains.

Key words:human rotavirus group A, outer capsid protein VP7, outer capsid protein VP4, phylogenetic analysis