HTLV-1 infection in Papua New Guinea: evidence for serologic false positivity

Serum samples from 557 individuals participating in studies from four separate lowland and highland populations in Papua New Guinea exhibited consistently false-positive results for human T lymphotropic virus (HTLV) type 1 (10%) and human immunodeficiency virus (HIV) type 1 (5%) antibody in direct antiglobulin and agglutination assays. All serum samples were negative in competitive ELISAs and radioimmunoassays for HTLV-1 and HIV-1; selected samples of reactive sera were negative in an HTLV-2 competitive ELISA. Immunofluorescent antibody tests using HTLV-1 infected cells correlated poorly with ELISA results. None of the sera from Papua New Guinea neutralized vesicular stomatitis virus pseudotypes of HTLV-1. By Western blot analysis, only three serum samples were weakly reactive to HTLV-1 gag proteins. These studies suggest there is as yet no firm evidence of HTLV-1, HTLV-2, or HIV-1 infection in Papua New Guinea, although there may be a low prevalence.