New Procedure to Test NDV Vaccines
By Sandra Avant
U.S. Department of Agriculture (USDA) scientists have developed an improved Newcastle disease virus (NDV) vaccine evaluation procedure that could be used to select better vaccines to treat the disease.
Newcastle disease, one of the most important poultry diseases worldwide, can cause severe illness in chickens and other birds. Severe, or virulent, strains rarely occur in poultry species in the United States, but they are regularly found in poultry in many foreign countries.
At the Agricultural Research Service's (ARS) Southeast Poultry Research Laboratory (SEPRL) in Athens, Georgia, microbiologist Claudio Afonso and veterinary medical officer Patti Miller have updated the traditional vaccine evaluation method, which does not compare vaccines or take into account suboptimal field conditions.
Under perfect conditions, vaccines should work, but conditions are not always perfect in the field, according to Miller. Chickens sometimes get less than the required vaccine dose and don't always have the minimum amount of time required to develop an optimum immune response.
Using the improved procedure, scientists inoculated chickens with different vaccine doses before exposure to a high dose of virulent NDV. Birds given the genotype-matched vaccine had reduced viral shedding, superior immune responses, reduced clinical signs, and increased survival than the birds vaccinated with a different-genotype vaccine. By using genotype-matched vaccines, viral shedding and death were significantly reduced.
ARS is USDA's principal intramural scientific research agency, and this research supports the USDA priority of promoting international food security.
Read more about this work in the April 2015 issue of AgResearch magazine.