Development of an alloantiserum (R2) that detects susceptibility of chickens to subgroup E endogenous avian leukosis virus

An alloantiserum, termed R2, specifically agglutinates red blood cells (RBC) from line 100B chickens that are susceptible to avian leukosis viruses (ALV) belonging to subgroups B and E, but does not agglutinate RBC from congenic inbred line 7(2 )chickens that are resistant to ALV B and E. The R2 antigen was also detected on lymphocytes and thrombocytes. Using chickens from a special cross, it was found that R2 reactivity requires that the chickens must: (1) be susceptible to infection by ALV-E; and (2) express a viral envelope gene with subgroup E specificity. With R2 antiserum, a nearly perfect association was observed between agglutination and susceptibility to ALV-B in F(2) chickens containing endogenous viral genes ev2 and/or ev3. These results support earlier evidence that ALV-B and ALV-E share receptors. Moreover, the R2 antiserum was shown to neutralize ALV-E. The R2 antigen showed Mendelian segregation in chickens of a commercial White Leghorn strain-cross containing ev3, ev6 and ev9. However, commercial chickens with or without the R2 antigen did not differ in susceptibility to lymphoid leukosis induction or immune response on infection with ALV of subgroup A for complex reasons we discuss.