Infectious Bronchitis Virus Surveillance in Broilers in California (2012-20)

Area of Science:

• Veterinary Virology
• Poultry Health
• Molecular Epidemiology

Background:

• Infectious bronchitis virus (IBV) causes significant economic losses in global chicken production.
• Understanding IBV's seasonal and spatial-temporal dynamics is vital for effective control in California broilers.

Purpose of the Study:

• To analyze seasonal and spatial-temporal trends of IBV prevalence in California broilers over eight years.
• To identify predominant IBV genotypes and track changes over time.

Main Methods:

• Retrospective analysis of 3439 suspected IBV broiler submissions (2012-2020).
• RT-qPCR screening of pooled tracheal, kidney, and cecal tonsil swabs.
• S1 gene sequencing and phylogenetic analysis of viral isolates.

Main Results:

• 1243 pooled samples tested positive for IBV, with higher prevalence in fall and winter.
• Identified an IBV hot spot near Livingston and cold spots near Riverdale.
• Detected shifts in predominant genotypes from IBV Cal 99 to IBV 3099, with a new variant emerging post-vaccination.

Conclusions:

• IBV prevalence exhibits distinct seasonal and spatial-temporal patterns in California.
• Genotype surveillance reveals dynamic shifts and the emergence of new variants, necessitating adaptive vaccination strategies.
• Continuous molecular surveillance is essential for managing IBV and preventing future outbreaks.