Abstract
A foamy virus isolated by Achong et al. from a human nasopharyngeal carcinoma was studied to determine its antigenic relationship to the eight known simiam foamy viruses (SFV). Using reciprocal cross-immunofluorescent and cross-neutralization techniques, we found the human isolate to be closely related to SFV type 6. In a seroepidemiological survey, neutralizing antibody to the human foamy virus was not detected in the sera of animal caretakers or laboratory personnel who routinely handled a wide variety of nonhuman primates. We conclude that the human isolate most probably represents a variant strain of SFV type 6.