Evaluation of a modified-live virus vaccine administered in ovo to protect chickens against Newcastle disease.
The B1 strain of Newcastle disease virus (NDV-B1), which is nonpathogenic for newly hatched chickens, killed embryos when it was used to inoculate chicken eggs at embryonation day 18. Treatment of NDV-B1 with an alkylating agent, ethylmethane sulfonate (EMS) markedly reduced the pathogenicity of the virus for 18-day-old chicken embryos. Eggs inoculated with the modified virus (NDV-B1-EMS) hatched, and the virus was isolated from lungs and spleen of 1-day-old chickens. The hatched chickens developed antibody to NDV and were protected against challenge exposure (at 4 weeks of age) with a highly virulent GB-Texas strain of NDV. Presence of maternal antibody to NDV in embryonating eggs did not influence the protective ability of NDV-B1-EMS, which also induced protective immunity when administered to 4-week-old chickens. The 50% protective dose of NDV-B1-EMS in maternal antibody-negative and -positive embryos was calculated to be 10.77 and 17.70 embryo 50% lethal doses, respectively. Results of the study indicated that NDV-B1-EMS may be used as an embryo vaccine to protect chickens against Newcastle disease.
Ahmad
J
J
Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Minnesota, St Paul 55108.
Sharma
J M
JM
D000818:Animals; D000914:Antibodies, Viral / Q000096:biosynthesis / Q000276:immunology; D002642:Chick Embryo / Q000276:immunology*; D002645:Chickens; D005020:Ethyl Methanesulfonate; D005069:Evaluation Studies as Topic; D009521:Newcastle Disease / Q000517:prevention & control*; D009522:Newcastle disease virus / Q000276:immunology*; D011201:Poultry Diseases / Q000517:prevention & control*; D014613:Vaccines, Attenuated / Q000276:immunology; D014765:Viral Vaccines / Q000276:immunology*
D000914:Antibodies, Viral; D014613:Vaccines, Attenuated; D014765:Viral Vaccines; D005020:Ethyl Methanesulfonate