Zoetis has expanded its line of recombinant vector vaccines with the launch of Poulvac Procerta HVT-IBD, which provides early protection against the contemporary infectious bursal disease (IBD) viruses confronting U.S. broilers.
“Poulvac Procerta HVT-IBD is a valuable tool for managing IBD due to the level of protection it provides and because of its early protection against IBD viruses, including the predominant AL2 variant,” said Angela Hartman, PhD, senior principal scientist at Zoetis and project team leader for development of the vaccine.
Kalen Cookson, DVM, director of clinical research for Zoetis, explained that early protection is essential because IBD, which remains a leading disease challenge for the poultry industry, tends to affect younger birds and is highly immunosuppressive.
Closes gap in protection
“The younger the bird, the more severe the immunosuppression. Immunosuppression may predispose birds to costly secondary infections — a greater concern now that nearly 60% of U.S. flocks are raised without antibiotics,” Cookson explained.
By providing early immunity, the veterinarian added, Poulvac Procerta HVT-IBD closes a gap in immunity.
“Maternal antibodies passed from immunized broiler breeders to broilers start to wane at about 14 days of age. Using Poulvac Procerta HVT-IBD closes the gap between passive immunity provided by hens and active immunity initiated by vaccination,” he said.
In challenge studies, Poulvac Procerta HVT-IBD administered in ovo provided 78% protection at 14 days of age against the AL2 variant, which now accounts for half of the IBD viruses circulating among U.S. broiler flocks.
The Zoetis team also conducted two separate studies to test the in ovo efficacy of Poulvac Procerta HVT-IBD against a classic virulent IBD challenge on day 14 of age. The new vaccine provided 96% protection.
According to Cookson, the vaccine’s duration of immunity is at least 63 days of age, which is important because IBD can also cause temporary immunosuppression in older birds. Poulvac Procerta HVT-IBD is therefore expected to be valuable for the layer as well as the broiler segments of the industry.
Optimized IBD virus insert
The backbone of the new vaccine is a turkey herpesvirus (HVT), which is widely known to be safe and protect against Marek’s disease (MD), another cause of immunosuppression.
The IBD gene inserted into the HVT backbone is optimized for viral protein expression in avian cells and is largely responsible for the vaccine’s ability to provide early IBD protection, according to principal scientist Hartman. The vaccine can be administered either in ovo or by subcutaneous injection at hatch.
For comprehensive IBD protection in broilers, Cookson recommended starting with a robust broiler breeder IBD vaccination program.
“If you use Poulvac Maternavac 4 in breeders and then follow up with Poulvac Procerta HVT-IBD in broilers, protection will be provided when maternal antibodies wane. Producers will therefore be protected from costly performance losses,” he said.
Poulvac Maternavac 4 is an inactivated, injected four-way vaccine for breeders introduced by Zoetis in 2019. Like Poulvac Procerta HVT-IBD, it has been shown to provide a high level of IBD protection.
For flocks with low maternal antibodies, Bursine -2 from Zoetis, a live vaccine for IBDV, can be used alone or following in ovo administration of Poulvac Procerta HVT-IBD. For strong field challenges, Zoetis offers Poulvac Bursaplex, another live IBD vaccine.
Building on 20 years of in ovo expertise
Poulvac Procerta HVT-IBD marks Zoetis’ second recombinant vaccine for poultry over the past 12 months. In January 2020, the company introduced Poulvac Procerta HVT-ND, which protects against MD and Newcastle disease. Both vaccines are backed by technical expertise and support associated with the Inovoject system, an Embrex biodevice and market leader for vaccination of eggs in ovo.