ABSTRACT.
ANTIGENIC PROPERTIES OF LENTOGENIC STRAINS OF THE NEWCASTLE DISEASE VIRUS. ESTIMATION OF THE LETHAL DOSE 50% FOR INMUNIZED CHICKENS

Sergio Rosende1, Héctor Hidalgo1 y Enrique Bergqvist2
 

B-1, La Sota and Palo Alto lentogenic strains of the Newcastle Disease virus (NDV) were used to inmunize 25-day-old broiler chickens, as a single dose. Differences in inmunogenecity were expresed in terms of the Lethal Dose 50% for Inmunized Chickens (LDIC60), defined as the lethal dose of a velogenic NDV able to infeet 50% of inmunized chickens with the aboye mentioned lentogenic strains. In this experiment, the B1-Hitchner and Palo Alto strains gave a LDIC50 of 8 X 105.0, and the La Sota strain gave a LDIC50 of 5.25 X 105.0. The-haemoaglutination inhibition antibody (IHA) values were not directly related to the level ofprotection obtained.

Keywords:
1Méd. Vet. y Méd. Ve., M.S., Departamento de Patología, Facultad de Ciencias Veterinarias, Universidad de Chile, Casilla 13, Correo 15, La Granja, Santiago, Chile.
2Méd. Vet., M.S., Programa Producción Avícola, Estación Experimental La Platina, Instituto de Investigaciones Agropecuarias (INIA), Casilla 10, La Granja, Santiago, Chile.