Evolution and Epidemic Spread of the Avian Infectious Bronchitis Virus (IBV) GI-23 in Brazil

Abstract

Infectious bronchitis virus (IBV) is a pathogen affecting poultry flocks worldwide. GI-23 is an IBV lineage with a rapid spread into different continents of the world, and it was reported for the first time in South American/Brazilian broiler farms last year. This study aimed to investigate the recent introduction and epidemic spread of IBV GI-23 in Brazil. Ninety-four broiler flocks infected with this lineage were evaluated from October 2021 to January 2023. IBV GI-23 was detected using real-time RT-qPCR, and the S1 gene hypervariable regions 1 and 2 (HVR1/2) were sequenced. S1 complete and HVR1/2 nucleotide sequence datasets were used to carry out phylogenetic and phylodynamic analyses. Brazilian IBV GI-23 strains clustered into two specific subclades (SA.1 and SA.2), both in tree branches with IBV GI-23 from Eastern European poultry-producing countries, suggesting two independent and recent introductions (around 2018). Viral phylodynamic analysis showed that the IBV GI-23 population increased from 2020 to 2021, remaining constant for one year and declining in 2022. S1 amino acid sequences from Brazilian IBV GI-23 presented specific and characteristic substitutions in the HVR1/2 for subclades IBV GI-23 SA.1 and SA.2. This study brings new insights into the introduction and recent epidemiology of IBV GI-23 in Brazil.

Molecular and Serological Investigation of Infectious Bronchitis Virus in the East Shewa, Central Ethiopia

“…Previously, the use of live attenuated vaccine was hypothesized to impact IBV genetic population structure. 11 The paragraph compares the development of IBV in different organ cultures such as chick kidney and trachea, and highlights that IBV develops well in the developing chick embryo, with the highest virus titer reached at 1 to 2 days after inoculation. The paragraph goes on to explain that there may be negative consequences to the embryo, with increased embryo mortality and dwarfism after the second passage.…”

“…S1 protein is also directly related to IBV antigenicity and the induction of neutralizing antibodies in the host. [7][8][9][10][11] IBV presents a high genetic heterogeneity, having previously been divided into 6 genetic types (GI-GVI) and 32 (1-32) lineages spread worldwide. The distribution and diversity of IBV varies remarkably among genotypes.…”