Current poultry challenges and vaccine solutions

Dear @Tarusenga Munyanyi,

In short, it is crucial to monitor the evolution of the virus and compare with the existing vaccine options. At Kemin Biologics we have a continuous monitoring programme and have continuous updates of the vaccine seed according to virus evolution. In addition, we offer vaccines with multiple viral clades included to provide a buffer for virus reassortment through cross-protection.

Here is some more extensive explanation:

As High Pathogenic Avian Influenza (HPAI) is an RNA virus, it is constantly undergoing changes as it replicates in its hosts. HPAI in particular, due to having a segmented genome undergoes changes more easily. The mutations can occur quickly or over a longer period of time and this is exactly why constant monitoring is paramount to assess the viral evolution and diversity.

The importance of this evolution is clear, as the protection granted by current vaccines is affected by its proximity with the field strains.
The available vaccines rely on using the HA (hemagglutinin) and also the neuraminidase of HPAI viruses. The HA is a very variable part of the virus which is responsible for the connection with the cell receptors in the host and also for the development of immunity in surviving or vaccinated animals.

HA homology is a very good indicator of the expected protection granted by a vaccine against a certain field strain, a thorough study on this can be seen on the EFSA report on HPAI vaccines which compares the antigenic distance based on the HA sequence and the HA sequence of the European HPAI consensus (European Union Reference Laboratory for Avian Influenza, EFSA Journal, 21(10), 1–87).

To assess that current vaccines are protective against currently circulating strains, it is also important to continuously monitor the serum of vaccinated chickens and its ability to inhibit the hemagglutination of red blood cells by the new isolated wild viruses. The vaccines should always provide at least 80% protection against a challenge by the wild viruses in question (recommended by the OIE).

Vaccines updates and inclusion of new strains are led by:
1) Homology – We continuously monitor the emergence of new strains and the strains circulating where we are present
2) HI performance – We continuously monitor the ability of the sera of vaccinated chickens to inhibit the hemagglutination of RBC by recent influenza viruses
3) Protection – Continuous monitoring of the protection of birds granted by vaccination against a challenge by a current virulent strain

From this continuous surveillance and monitoring, we, at Kemin Biologics, have developed our 5th iteration of our seed in the HPAI vaccines.

Kind regards,
Matias