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

Area of Science:

• Veterinary Virology
• Poultry Disease
• Molecular Epidemiology

Background:

• Increasing detection of infectious bronchitis virus (IBV) positive samples that are negative in established variant-specific PCR tests since mid-2015.
• These unidentified IBV strains exhibit significant genomic divergence, particularly in the S1 gene (57-61% nucleotide similarity to known genotypes GI-GVII).

Purpose of the Study:

• To characterize a novel IBV strain detected in poultry flocks.
• To propose a new genotype designation for this divergent IBV strain based on genomic analysis.

Main Methods:

• Screening PCR for IBV detection.
• Variant-specific PCR assays for known IBV genotypes.
• Partial viral genome sequencing.
• Phylogenetic analysis and comparison with existing IBV strains in the NCBI database.

Main Results:

• Identification of IBV strains with low S1 gene nucleotide similarity (57-61%) to known IBV genotypes.
• The closest related strain identified is PA/1220/98 (AY789942), with ~80% S1 gene identity.
• The novel strain, designated IB80, has been detected in commercial layer, broiler parent, and broiler flocks in Europe and beyond.

Conclusions:

• The distinct genetic makeup of IB80 warrants its classification as a new IBV genotype, GVIII.
• The emergence and spread of IB80 pose a threat to poultry health and production, evidenced by production drops.
• Further surveillance and characterization of IB80 are crucial for effective disease control strategies in the poultry industry.