Virus Dilution Affects the Anti-Rous Sarcoma Response of Progressor but not Regressor Major Histocompatibility (B) Complex Genotypes

Abstract

Responses to tumors induced by three dilutions of Rous sarcoma virus (RSV) were studied in UNH 105, a noninbred line of New Hampshire chickens. Single-male matings produced progeny of three B genotypes: B23/B23 (tumor regressor) and B23/B24 and B24/B24 (tumor progressors). A total of 223 6-wk-old chicks were wingweb inoculated with one of three dilutions (10−3, 4 × 10−3, and 10−4) of a pseudotype of Bryan high titer RSV designated as BH RSV (RAV-1). A tumor profile index (TPI), an indicator of antitumor response, was assigned to each chick based on six postinoculation tumor size scores. Incidence of mortality was itemized for B genotypes at each virus dilution and the number of days to death (DTD) was recorded for 44 chicks with terminal tumors.Analysis of mean TPI revealed a virus dilution × B genotype interaction, with significant differences among B24/B24 chickens at a 10−3 virus dilution (TPI 3.1), a 4 × 10−3 virus dilution (TPI 2.6), and all other subclasses (TPI 1.8 or less). Both virus dilution and B genotype affected the incidence of mortality as shown by chi-square analysis. These data demonstrate that virus dilution influenced the antitumor response in progressor but not in regressor B complex genotypes.