Does simian virus 5 infect humans?

Simian virus 5 (SV5) isolates derived after co-cultivation of human bone marrow aspirates of multiple sclerosis (MS) patients were shown by immunoprecipitation, cross-neutralization and haemagglutination inhibition techniques to be similar antigenically but not identical to the prototype strain. Analyses of human sera (MS and control) showed that about 20% contained neutralizing antibodies to SV5 and immunoprecipitated the specific SV5 HN polypeptide. A competition assay using a specific SV5 monoclonal antibody confirmed that a human serum containing such neutralizing activity also blocked a specific SV5 epitope whereas another human serum with demonstrable antibodies to the related human parainfluenza virus type 2 did not block this epitope. These tests therefore suggested that SV5 can infect humans. However, there was no indication, on the basis of these tests, of any aetiological relationship of the SV5 infection to the induction of MS.