IB80-A Novel Infectious Bronchitis Virus Genotype (GVIII).

Abstract

Since mid-2015, there has been an increasing number of chicken samples that are positive for infectious bronchitis virus (IBV) in a screening PCR but which do not show positive results in any established, variant-specific PCR tests (793B, QX, D1466, Massachusetts, D274, Italy 02, Arkansas, Variant 2, Q1). Partial sequencing of the viral genome of those samples shows great similarities, but nucleotide similarity in the S1 gene is only about 57%-61% when compared to any other known GI-GVII IBV genotype and lineage. With nucleotide identity in the S1 gene of approximately 80%, the closest related strain in the National Center for Biotechnology Information database (as of March 15, 2020) is the North American PA/1220/98 isolate (AY789942) designated as a unique variant by Valastro et al. in 2016. Due to its divergence from other IBV strains, we propose that strain, designated IB80, is the type strain of a novel IBV genotype GVIII. So far, IB80 has been detected in commercial layer and broiler parent flocks, frequently showing severe drops in egg production as well as in broiler flocks in Europe and beyond.