Antigenic Differences Among Strains of Newcastle Disease Virus.

Abstract

Immune sera were prepd. for strains of Newcastle disease virus isolated from many localities in the U. S., Canada and Mexico and from a few places in the Old World. Results in 17 heterologous combinations of Newcastle disease virus and antiserum, tested by the serum neutralization procedure, are reported. Of these combinations, 13 exhibited a probably significant difference of greater than 1 log between the neutralization of the homologous and the heterologous virus by prepd. antiserum. A very significant difference of 5 logs was observed between 2 strains. The study of antigenic diversity of strains of Newcastle disease virus, while still in preliminary stages, revealed differences of diagnostic importance and raised a question of the feasibility of using a vaccine prepd. from one antigen in all situations.