The role of the S1 gene in glandular stomach pathogenesis and tropism of infectious bronchitis virus H120 strain in poultry.

Abstract

UNLABELLED: Infectious bronchitis virus (IBV) H120 strain, a widely used vaccine in poultry production, has been associated with an increased incidence of avian glandular and muscular stomach inflammation. This study aimed to investigate the pathogenic factors of stomach inflammation induced by the IBV H120 vaccine and identify genetic regions affecting glandular and muscular stomach lesions through the construction of recombinant strains. Our findings revealed that the H120 strain exhibits a more pronounced tropism for the glandular and muscular stomach compared to the 4/91 strain. Notably, the replacement of the S1 gene in the H120 strain resulted in reduced pathogenicity in the chicken's glandular stomach. These results suggest that the S1 gene of the H120 strain plays a critical role in viral replication within the chicken stomach, contributing to the development of muscular and glandular stomach lesions. This research provides valuable insights into the pathogenesis of IBV and offers potential strategies for optimizing vaccine strains by targeting the S1 gene to minimize viral load in the glandular and muscular stomachs, ultimately improving poultry health and productivity. IMPORTANCE: Infectious bronchitis virus (IBV) causes high morbidity and mortality worldwide, leading to significant economic losses. While the widespread vaccination with the H120 strain has effectively curbed the spread of IBV, we have discovered that the H120 strain can cause glandular stomach inflammation in chickens. Further research indicates that the S1 gene of the H120 strain determines its tropism for the glandular stomach. Studying the glandular tropism of the H120 strain is crucial for developing effective and safe IBV vaccines.