Specific Absorption of Antibody with Extracts Containing the Rabbit Papilloma Virus (Shope)

Abstract

The papilloma virus, or a substance that has proved inseparable from it, reacts with specific immune sera to fix complement, as previous studies have shown; 1 and tests made recently with more than a score of such sera have borne out a finding already obtained, namely that the virus-neutralizing ability of any serum is directly proportional to its complement-fixing capacity. The present work was undertaken to learn whether the virus-neutralizing and complement-fixing antibodies can be absorbed from the immune sera; and, if so, whether they are absorbed together, and what is responsible for their removal.

A number of immune sera have been used, some obtained from cottontail rabbits with naturally-occurring growths and others from wild and domestic rabbits with experimental papillomatosis. Various dilutions of the sera were made with saline, from 1:2 to 1:64 or higher, and these were mixed in equal parts with clear, saline extracts of the virus-induced growths, either as such or after Berkefeld filtration, in dilutions up to 1:640. The mixtures were put into the water-bath at 37°C for 2 hours, then kept overnight in the refrigerator. The relative amount and character of the specific visible flocculation, which was regularly present in the tubes containing antigen and antibody in optimal proportions, were then recorded, and the mixtures were spun at 4400 rpm for 20 minutes in an International centrifuge with 51°-angle head. The supernatant fluids thus obtained were now tested for content of virus, complement-fixing antigen and antibody, by means of standard pathogenicity, neutralization, and complement-fixation tests which have been already described. 2

In every one of 7 experiments, in which extracts containing the virus were mixed with immune sera in optimal proportions, tests of the sort described showed that absorption of antibody had occurred; and the complement-fixing and virus-neutralizing capacities of the sera were always proportionately reduced.