COMPARATIVE PERFORMANCES OF ENZYME-LINKED IMMUNOSORBENT, WESTERN-BLOT, AND POLYMERASE CHAIN-REACTION ASSAYS FOR HUMAN T-LYMPHOTROPIC VIRUS TYPE-II INFECTION THAT IS ENDEMIC AMONG INDIANS OF THE GRAN-CHACO REGION OF SOUTH-AMERICA

BACKGROUND: Human T-cell lymphoma/leukemia viruses types I and II (HTL V-I and HTLV-II) are related exogenous human retroviruses. The former is definitely pathogenic, while disease association with the latter is unclear There are two subtypes of HTLV-II, A and B. Currently, enzyme -linked immunosorbent assays (ELISAs) based on HTLV-I antigens are use d to screen for the presence of HTLV-I and -II antibodies. Confirmatio n and subtyping are accomplished by Western blot (WE) or ELISAs based on HTLV-I whole viral antigens and/or HTLV-I and HTLV-IIA peptides. Th e sensitivity and specificity of these serologic assays were compared to those of HTLV-I- and -II-specific polymerase chain reaction (PCR) a ssays in tests on samples from Indians from South America in whom the HTLV-IIB subtype is endemic. STUDY DESIGN AND METHODS: Sera from 246 G ran Chaco Indians were evaluated for HTLV antibodies with the use of f our ELISAs (Retrotek HTLV-I; Cambridge Biotech rgp21-enhanced HTLV-I/I I; Vironostika HTLV-I/II; and Select HTLV-I/II), and a WE assay. Perip heral blood leukocyte DNA from each Indian was analyzed for HTLV-I or HTLV-II pol DNA via PCR. Fifteen of the PCR-positive samples were furt her subtyped via cloning and sequencing and/or oligomer restriction. R ESULTS: Ninety-seven samples (39%) were positive for HTLV-II by serolo gic and/or PCR assays. All 15 positive DNA samples that were further a nalyzed were of the HTLV-IIB subtype and were clustered as a highly co nserved phylogenetic group. Comparative analyses indicate that the sen sitivity and specificity of the various assays were: PCR, 97 and 100 p ercent; Retrotek, 70 and 91 percent; Cambridge Biotech, 74 and 96 perc ent; Vironostika, 73 and 99 percent; Select, 72 and 98 percent; and WE , 70 and 100 percent. CONCLUSION: The sensitivities of the tested HTLV serologic assays were comparable. However, the specificity of the Ret rotek ELISA was significantly lower than that of the others. When posi tive, the subtyping assays were very specific. However, PCR assays wou ld seem preferable or to be a necessary adjunct for the sensitive dete ction of HTLV-IIB infection.