Isolation of high and low molecular weight components from chicken sera that have Rous sarcoma virus neutralizing activity.

Blood sera components from Arkansas regressor line (R-line) and progressor line (Pr-line) chickens are compared for the first time for Rous sarcoma virus neutralizing activity. Sera was fractionated by Sephadex G-100 filtration into a high molecular weight fraction I (HMW-I) and a low molecular weight fraction II (LMW-II) component (HMW-I greater than 14,000 daltons, LMW-II less than 5,000 daltons). Both fractions from each line of chickens exhibit activity against Rous sarcoma virus (RSV) judged by a wing web assay. Both HMW-I (principally antibodies) and LMW-II neutralized RSV when obtained from hyperimmune R-chickens and Pr-chickens with large progressing tumors. However, HMW-I and LMW-II obtained from R- or Pr-chickens before challenge contain so RSV neutralizing activity. The novel low molecular weight fraction II disappeared from the sera of R-line chickens 2 weeks after tumor regression, whereas the HMW-I persisted after tumor regression.