Genetic diversity of Bordetella pertussis strains isolated during 2019-2020 in Hebei province
Objective To explore the genetic diversity of Bordetella pertussis(Bp)strains isolated in Hebei province.Methods We selected Bp isolates from 2019 to 2020 in Hebei Children's Hospital for next generation sequencing.We assembled and spliced sequences to obtain whole genomes for multilocus sequence typing(MLST),multilocus antigen sequence typing(MAST),multilevel genome typing(MGT),Bp vaccine antigen typing(BPagST),and 23S rRNA gene mutation analyses.Results A total of 62 Bp strains were obtained;all were MLST type ST-2,among which 56 carrying the ptxP1 gene had 23S rRNA gene A2047G mutations compared with vaccine strains(6 had Prn gene deletion),and 6 strains carrying the ptxP3 gene did not have mutations.Six MAST types were detected,among which the type prn1/ptxP1/ptxA1/fim3-1/fim2-1 was detected in 47 strains.There were 1,2,3,14,and 52 MGT types from MGT1 to MGT5 levels,respectively.BPagST types included BPagST-37(56 strains)and BPagST-4(56 strains).Conclusions The main virulence protein genes and core genomes of Bp isolates were significantly changed compared with vaccine strains,possibly leading to immune escape of circulating BP strains from vaccination.We suggest strengthening Bp genome monitoring.