A strategic approach to combat infectious bronchitis in broilers

IB vaccine combinations may offer cross-protection against emerging strains such as DMV/1639.

Infectious bronchitis is an especially challenging respiratory virus that can be a moving target for vaccination strategies. Serotypes can quickly evolve and evade established vaccines, so monitoring and identifying circulating serotypes is crucial for developing an effective vaccine approach, said Kalen Cookson, DVM, MAM, DACPV, director of clinical research, Zoetis.

Bronchitis prevention basics

Infectious bronchitis control requires tailored vaccination programs that combine various viral serotypes that result in homologous immunity (vaccine and field virus are same serotype) and heterologous immunity (vaccine and field virus are different serotypes), Cookson explained.

As a first step, a diagnostic survey of the prevalent field challenge strains affecting a poultry complex will help inform a vaccination strategy.

This strategy is especially important for strains without a homologous commercial vaccine, such as DMV/1639, which was the third-most isolated serotype and most common wild type in 2020. However, heterologous strains, such as GA08 and Mass, may offer cross-protection while allowing continued surveillance of the DMV/1639 wild type.¹

A combination approach for better protection

Studies suggest that pairing Poulvac® IB Mass with a GA08 vaccine may cross-protect better against the DMV/1639 strain than either Mass or GA08 alone.^2-5  

While other monovalent Mass vaccines are available, Cookson said other factors demonstrate the value of Poulvac® vaccines as reliable vaccination options, including:

• Poulvac IB Mass gives excellent takes without being too reactive.
• Utilizing Poulvac Aero®, a vaccine with Newcastle disease B1 plus Mass serotype, is a good starting live primer for ND protection along with IB protection. The B1 strain in Poulvac Aero is not overly aggressive yet effective against an NDV challenge.

Paired vaccine efficacy confirmed in research study

A study was conducted to evaluate the efficacy of various commercial IB Mass (two commercial products) and GA08 (two commercial products) vaccine combinations against serotypes for a DMV/1639 challenge.²

In the study, 540 one-day-old chicks were divided into five groups of 90 birds and further grouped in five cages (vaccine treatment) with 18 birds per cage. Each group received one of the vaccine treatments by spray at the dosage of 14 mL/100 chick. At 25 days of age, birds in three cages per group were challenged by eye/nose drop with DMV/1639 IBV.

Cookson said the study showed that Mass+GA08 vaccine combinations can protect birds from a significant DMV/1639 challenge, but numerical differences were observed (Figure 1).²

Based on grade 3 and 4 tracheal lesions, Poulvac IB Mass/Poulvac Bron GA08 resulted in 76% protection whereas the competitor IB Mass/Poulvac Bron GA08 combination provided only 52% protection (Figure 1).²

In order to best protect birds, it is important to choose a vaccine, or combination of vaccines, based on the prevalence of different strains in the area and on the farm itself, Cookson said. There are more tools available to use to monitor circulating viruses that can inform bronchitis vaccination planning for individual farms.

To learn more about these studies or to request help diagnosing your specific field challenge, contact your Zoetis representative.

Figure 1. Evaluation of different GA08 and Mass vaccine combinations challenged with DMV/1639 at 25 days of age.² 

^a,bValues with different letters are significantly different (p < 0.05).

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References:

¹ Data on file, Study Report No. 032419-KL-70AQ0-KC6120, Zoetis Inc.
² Data on file, Study Report No. RM-0Q0-KC6620, Zoetis Inc.
³ Data on file, Study Report No. 01-18-70AQ1, Zoetis Inc.
⁴ Data on file, Study Report No. RM-0Q0-KC6930, Zoetis Inc.
⁵ Jordan B, Reith A. Results of an infectious bronchitis virus surveillance program in broiler chickens. In: Proceedings, Southern Conference on Avian Diseases, International Poultry Science Forum. 2021:T7.

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