A seroepidemiological survey of the human syncytial (foamy) virus was done by means of an indirect immunofluorescence test on 1,717 sera from nine different Pacific island territories. The specificity of the reaction was verified by neutralization tests. The study indicated that the virus is ubiquitous in this part of the world, with no region being entirely free of antibody. The antibody prevalence ranged from a low of 1.2% in Ponape to a high of 15.6% in the Cook Islands. The average prevalence for the nine insular communities was 6.9%.

Human syncytium-forming (foamy) virus was labeled with 3H-uridine and banded isopycnically in sucrose gradients (buoyant density = 1.16 to 1.18 g/cm3). Viral RNA extracted from the banded virus was analyzed either by rate zonal separation in sucrose gradients or by polyacrylamide-agarose gel electrophoresis. The results indicated that purified HSFV contains a 60S RNA component plus several smaller molecular weight RNA components. On dissociation with heat, smaller RNA structures were released from the 60S component. These results indicate that the genome of HSFV, like the other members of the Retroviridae family, is composed of an aggregate of several RNA species.