Enhancing Poultry Health: The Efficacy of Combined Vaccination Against IBV-QX
In the realm of commercial poultry, the Infectious Bronchitis virus (IBV) poses a significant threat, leading to substantial economic losses globally. This virus causes serious respiratory complications in broilers and adversely affects egg production in layers.
Challenge of Controlling Emerging Variants
While vaccination remains a pivotal strategy in combating this disease, the constantly evolving nature of IBV strains, particularly QX-like variants, complicates effective control measures. Our study aimed to assess the effectiveness of two live attenuated vaccines, IB VAR 2 and IB H120, administered orally to specific-pathogen-free (SPF) layer chickens against the virulent IBV-QX strain.
Research Methodology
A total of 150 SPF chickens were divided into five distinct treatment groups. Three groups were subjected to a specific vaccination protocol followed by exposure to an IBV-QX challenge infection on day 28. The study parameters included:
- Vaccines: IB VAR 2 and IB H120
- Challenge route: Orally
- Challenge strain: QX strain (2022 European isolate)
- Challenge dose: 4 Log10 EID50 / bird
- Metrics: ELISA and HI titers, lesion score, viral shedding.
Analyzing Immune Responses
The immune responses of the birds were evaluated through ELISA and Hemagglutination Inhibition (HI) testing. Results indicated that all vaccinated groups developed specific antibodies targeting the QX strain, with groups T03 and T04 showing significantly higher antibody titers, thus reflecting a robust immune defense against IBV-QX.
Histopathology and Viral Load Analysis
The respiratory health of the chickens was assessed using tracheal histopathology scores. Notably, the group receiving a combination of IB VAR 2 and IB H120 on day zero, followed by an IB H120 booster on day 14 (T05), demonstrated the lowest histopathology scores, indicating effective protection against IBV-QX infections.
Additionally, viral load was assessed through qPCR examining viral shedding. Results showed a marked reduction in viral replication within all vaccinated groups, particularly in group T04, which exhibited the lowest levels of viral shedding, indicating an effective control over the virus’s transmission.
Conclusion
This study concludes that the combination of IB VAR 2 and Mevac IB H120 vaccines provides robust protection against the IBV-QX strain. Both vaccines can be safely administered to day-old chicks, initiating strong local and systemic immunity, effectively minimizing viral shedding and the risk of horizontal transmission.
For more insights on vaccination against Infectious Bronchitis, visit:
