7th International AIDS Conference Florence, Italy — June 16-21, 1991

Int Conf AIDS 1991 Jun 16-21; 7:29 (abstract no. M.A.29)
Smith D, Mann T, Anderson E, Canavaggio M, Lee H; Abbott Laboratories, North Chicago, IL

OBJECTIVE: HTLV-I EIA screening assays and the confirmatory procedures of Western blot (WB) and radioimmunoprecipitation (RIPA) show reactivity with antibodies to HTLV-I and the closely related HTLV-II. Patterns of serologic reactivity were compared to HTLV-I or II PCR results.

METHODS: 181 serologically confirmed samples were evaluated by PCR using a primer pair in the tax/rex region to discriminate HTLV-I or II infection. To study potential HTLV heterogeneity, a subset of 76 specimens was further tested using multiple primers to amplify either homologous or unique sequences of HTLV-I or II.

RESULTS: 62/181 (34%) specimens were HTLV-I, 90/181 (50%) were HTLV-II and 29/181 (16%) were PCR negative. Of the HTLV-I specimens, 95.2% (59/62) had p19 on WB. However, HTLV-II samples showed a more hetergeneous pattern: 43/90 (48%) with p24 only on WB and 47/90 (52%) with both p19 and p24. For most of the samples, HTLV infections were confirmed by amplification of tax/rex, env p21, and gag p19 regions. For 56/62 samples, the PCR reactivity of different primers was generally equivalent. Several samples reacted only with selected primers: 1 HTLV-I and 1 HTLV-II sample had weak tax/rex reactivity only. Three HTLV-II infected DNA's lacked tax/rex reactivity and 1 HTLV-II sample showed only env p21 amplified sequences.

CONCLUSIONS: Because current serologic methods for HTLV show cross reactivity for HTLV-I and II, discrimination of these closely related viruses should be determined by PCR or peptide specific assay.

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