Emergence of novel QX-type IBV in China: molecular insights into unique S protein cleavage sites, antigenic drift, and enhanced pathogenicity (2025).

ABSTRACT: Avian infectious bronchitis virus (IBV) is a major pathogen impacting the global poultry industry. The QX genotype (GI-19 lineage) of IBV has rapidly spread worldwide and is now the dominant genotype in Asia and Europe. In this study, three QX-type field strains (JS/773, JS/774, and SD/783) were isolated from diseased chicken flocks in eastern China, which had been vaccinated with IBV live attenuated vaccines (H120 or QXL87) between December 2024 and January 2025. Notably, the JS/773 strain showed an H536P mutation at the S protein cleavage site, marking the first identification of a PRRRR cleavage motif in this lineage and highlighting the diversity of cleavage sites among QX-type strains. Recombination analysis showed that these isolates are recombinant variants from vaccine strains 4/91

SUBMITTER: Zhang J 

PROVIDER: S-EPMC12866055 | biostudies-literature | 2025 Dec

REPOSITORIES: biostudies-literature