Genome Variability of Infectious Bronchitis Virus in Mexico: High Lineage Diversity and Recurrent Recombination.

The avian infectious bronchitis virus (IBV) is a coronavirus that mutates frequently, leading to a contagious and acute disease that results in economic losses to the global poultry industry. Due to its genetic and serological diversity, IBV poses a challenge in preventing and controlling the pathogen. The full-length S1 sequence analysis identifies seven main genotypes (GI-GVII) comprising 35 viral lineages. In addition to the previously described lineage, a new GI lineage (GI-30) and two lineages from novel genotypes (GVIII-1 and GIX-1) have been described in Mexico. To prevent the spread of IBV outbreaks in a specific geographic location and select the suitable vaccine, it is helpful to genetically identify the circulating IBV types. Moreover, sequencing genomes can provide essential insights into virus evolution and significantly enhance our understanding of IBV variability. However, only genomes of previously described lineages (GI-1, GI-9, GI-13, and GI-17) have been reported for Mexican strains. Here, we sequenced new genomes from Mexican lineages, including the indigenous GI-30, GVIII-1, and GIX-1 lineages. Comparative genomics reveals that Mexico has relatively homogenous lineages (i.e., GI-13), some with greater variability (i.e., GI-1 and GI-9), and others extremely divergent (GI-30, GVIII-1, and GIX-1). The circulating lineages and intra-lineage variability support the unique diversity and dynamic of Mexican IBV.

Research Note: High genetic diversity of infectious bronchitis virus from Mexico.

The avian infectious bronchitis virus (IBV) is a highly mutable coronavirus that causes an acute and highly contagious disease responsible for economic losses to the poultry industry worldwide. Preventing and controlling bronchitis disease is difficulted by the numerous IBV circulating types with limited antigenic cross-protection that hamper the prevention and control by heterologous vaccines. The coding region of the variable spike S1 receptor-attachment domain is used to classify IBV in 7 genotypes (GI-GVII) comprising 35 viral lineages (1-35). Knowledge of the circulating IBV types causing outbreaks in a specific geographic region is beneficial to select better the appropriate vaccine(s) and contribute to disease control. In the study, 17 avian infectious bronchitis virus strains were obtained from chickens showing signs of illness in Mexico from 2007 to 2021. We detected 4 lineages within genotype I, three already known (GI-3, GI-9, GI-13) and one newly described (GI-30). In addition, we identified 2 divergent monophyletic groups that are tentatively described as lineages of new genotypes (GVIII-1 and GIX-1). Our findings revealed that Mexico's high genetic IBV diversity results from the co-circulation of divergent lineages belonging to different genotypes. Mexican IBV lineages differ significantly from Massachusetts and Connecticut vaccine strains, indicating that the currently used vaccines may need to be updated.