Neutralization of Mason-Pfizer virus by sera from patients treated for renal disease.
Sera from 67 patients treated for renal diseases were assayed by as many as three different tests for activities against Mason-Pfizer virus (M-P V) antigens. Firstly, in patients studied before kidney transplantation, neutralizing activity against syncytium-forming units of M-P V was found in 50% of 24 cases of chronic glomerulonephritis but in only 10% of 20 cases with other diseases (P less than 0.01). These proportions were higher after treatments accompanying transplantation since, of the 19 patients without antibodies before graft, 53% showed a sero-conversion after this treatment. The incidence of M-P V antibodies did not correlate with the number of transfusions received by the patients. Neither did these antibodies correlate with the presence of antibodies to antigens associated with baboon endogenous virus or simian sarcoma virus; antibodies to the latter two viruses were found in 6 to 21% of the sera, with no specific distribution among the sera. Secondly, pseudotypes of vesicular stomatitis virus with M-P V antigens in their envelope were prepared; they were inactivated by 90% of the sera which neutralized M-P V syncytium forming units and by none of the negative sera. Thirdly, specific complement-dependent cytotoxic antibodies to HeLa cells producing M-P V were also found in 61% of the sera with neutralizing activity to M-P V and only in 12% of the sera which did not neutralize M-P V. Absorption experiments indicated that the serum activities against M-P V associated antigens were not due to anticellular antibodies directed against normal constituents of human cells. However, no evidence has been provided that the M-P V associated antigens reacting with the human sera were virus coded.