As of 2018, the IBV D181 strain is regularly found in Dutch layer and parent flocks, which suffer decreased egg production, reduced egg quality and increased mortality. In research commissioned by the poultry sector, GD discovered that D181 can also cause false layer syndrome, as well as renal damage in young chicks. This makes it all the more important to generate high degrees of protection against this strain. As there is no commercial vaccine to combat D181, it was time to study the effect of various vaccine combinations.
There is no specific vaccine available to combat IBV strains. Yet a combination of IBV vaccines might induce cross-protection thereby rendering the virus harmless. In this case the vaccine combinations would have to generate so-called ‘neutralising antibodies’. In 2021, GD assessed four different vaccination programmes via the volume of neutralising antibodies against D181 generated by them. Four living IB vaccine strains were used (Mass, D274, 4/91-793B and QX), the maximum possible in the Netherlands. The effect of an additional vaccination using the most commonly applied inactivated vaccine (Nobilis® IB Multi) was then compared versus that of a D181-autovaccine. These two vaccines were also tested as a combination.
1. The study showed that good levels of neutralising antibodies against D181 were only achieved in the vaccination programmes where an individually produced oil-emulsion-vaccine (OEV) against IBV-181 was applied.
2. The tested combination of the four living commercial vaccines resulted in little to no measurable development of neutralising antibodies against D181.
As a result of this study and the previous research on D181, GD advises as follows:
- A good quality D181 oil-emulsion-auto vaccine (OEV) is an effective option for useful development of titres to combat D181. The tested vaccine combinationswithout this vaccine produced low neutralising antibody titres against D181.
- Vaccination of layer parent animals with a D181-OEV induces high titers, which is important in the prevention of false layer syndrome due to D181.
This study is part of the 2021 research and innovation programme of the poultry sector. This programme is coordinated by AVINED and financed by the poultry sector.