Genetic and antigenic heterogeneity of GI-1/Massachusetts lineage infectious bronchitis virus variants recently isolated in China

Abstract

Four GI-1/Massachusetts-type (GI-1/Mass-type) infectious bronchitis virus ( IBV ) strains were isolated and the complete genomes of these isolates, coupled with the Mass-type live-attenuated vaccine H120 and the Mass-type pathogenic M41 strains, were sequenced in the present study. Our results show that isolates LJL/140820 and I0306/17 may be derived from the Ma5 (another Mass-type live-attenuated vaccine strain) and H120 vaccine strains, respectively. The I1124/16 strain was found to be a M41 variant that likely resulted from accumulated mutations in the genome. Consistently, the results of the virus neutralization (VN) test showed that isolate I1124/16 was antigenically related but slight different from the M41. Our results from the protection experiments pointed out that chickens immunized with H120 failed to eliminate viral shedding after infection with the isolate I1124/16, which was different from that of M41; this result was consistent to the field observation and further implicated that the variant IBV isolate I1124/16 was antigenic different from M41 strain. Furthermore, the I1124/16 was found to have comparable but slightly lower pathogenicity with M41 strain. More studies based on the reverse genetic techniques are needed to elucidate the amino acids in the S1 subunit of spike protein contributing to the altered antigenicity of the isolate I1124/16. In addition, an IBV isolate, LJL/130609, was found to be originated from recombination events between the I1124/16- and Connecticut-like strains. Our results from VN test also showed that isolates LJL/130609 and I1124/16 were antigenic closely related. Hence, there are at least three different genetic evolution patterns for the circulation of the GI-1/Mass-type IBV field strains in China. The differences of vaccines used, the field conditions and genetic pressures between different flocks, likely account for the emergence, evolution patterns and characteristics of the Mass-type IBV strains.

Design and Characterization of a DNA Vaccine Based on Spike with Consensus Nucleotide Sequence against Infectious Bronchitis Virus

“…Currently, the most commonly used IBV vaccines—live attenuated, or killed vaccines derived from classical or variant serotypes—can only act against strains of the same serotype [ 11 ]. Furthermore, the continuous emergence of new IBV serotypes makes the control and prevention of the virus infection more complex [ 6 , 27 , 28 , 29 ]. Moreover, the high cost and labor-intensive process hamper the development of vaccines against the new IBV variants.…”

Genotyping and phylogeography of infectious bronchitis virus isolates from Pakistan show unique linkage to GI-24 lineage

“…Based on the full S1 sequence, a new system for IBV genotype classification is also suggested which categorizes IBV in 7 genotypes (GI–VII) with multiple lineages ( Valastro et al, 2016 ; Houta et al, 2021 ). Commonly circulating Pakistani strains like M-41 belongs to the GI-1 lineage, while 4/91 belong to GI-13 ( Rohaim et al, 2019 ; Sheng et al, 2020 ). The emergence of these new genotypic lineages and strains also vary in their pathogenicity and target organs making IB a multisystemic disease ( Meulemans et al, 2001 ).…”