All repeatedly reactive samples are to be subjected to additional, more specific supplemental tests. Samples with positive or indeterminate test results on Western blot are also subjected to additional tests, according to the algorithm described in Figure 2 (Page 24). The purpose of the supplemental tests is to resolve indeterminate test results and to distinguish between antibodies to HTLV-I and HTLV-II. All supplemental/confirmatory test results for HTLV-I and HTLV-II are labeled "For Research Use Only" and have not been licensed by the FDA.

INTERPRETATION OF WESTERN BLOT FOR HTLV-I/II

NEGATIVE - No viral bands detected.

POSITIVE - Sample contains antibodies to p24 (gag) and p21 (recombinant env) or gp46 (env).

INDETERMINATE - All other patterns (more than 50% of the samples routinely analyzed yield indeterminate Western blot results).

SUPPLEMENTAL TESTING FOR HTLV-I/II

Peptide Assays. Samples with positive or indeterminate Western blot results are to be tested with a synthetic peptide EIA specific for HTLV-I and HTLV-II. The tests are based on epitopes of env products of the virus. Final interpretations are summarized in Table A-5.