ANTIGENIC RELATIONSHIPS AMONG FROG VIRUSES DEMONSTRATED BY PLAQUE REDUCTION AND NEUTRALIZATION KINETICS TESTS

Antisera to several different cytoplasmic frog virus isolates were prepared in rabbits. Comparison of eight virus isolates by means of 50% plaque reduction tests revealed no antigenic differences. In neutralization kinetic studies of three isolates, LT-1, LT-2, and FV-1, very low neutralization rate constants (K = 0.18-2.9) and high persistent fractions of nonneutralizable virus (14-38%) were obtained. No antigenic differences were detected, although one isolate, LT-2, consistently gave lower K values and higher persistent fractions with homologous and heterologous sera than did LT-1 and FV-1. It is concluded that all the cytoplasmic frog viruses studied, originating from normal and tumor-bearing frogs from widely separated parts of the United States, comprise a single serotype. © 1968.