Characterization of Newcastle disease viruses isolated from migratory waterfowl in the Atlantic flyway

Four isolants of Newcastle disease virus (NDV) obtained from free-flying Canada geese in the Atlantic flyway were characterized and compared with the B1, LaSota, Roakin, and Texas-GB strains of NDV. The 4 isolants were identified as lentogenic strains on the basis of embryo mean death times of greater than 100 hours and relative lack of pathogenicity for 1-day-old and 3-week-old chickens. The hemagglutinin of 2 of the isolants was stable at 56 C for 15 minutes, 1 for 30 minutes, and the other for at least 2 hours. When held at 4 C for 24 hours, none of the 4 isolants could be eluted from chicken erythrocytes. All 4 of the isolants produced plaques in chicken embryo fibroblast cell cultures without additives, whereas the B1 and LaSota strains did not. The 4 lentogenic NDV isolants from Canada geese differed in many respects from currently used commerical vaccine strains (B1 and LaSota).