CONTRIBUTION OF POLYMERASE CHAIN-REACTION AND RADIOIMMUNOPRECIPITATION ASSAY IN THE CONFIRMATION OF HUMAN T-LYMPHOTROPIC VIRUS-INFECTION INFRENCH BLOOD-DONORS

Background: To verify the criteria for human T-lymphotropic virus (HTL V) seropositivity in Western blot (WB) proposed by the Retrovirus Stud y Group of the French Society of Blood Transfusion, 186 blood donation s that were repeatably reactive in HTLV enzyme-linked immunosorbent as say, selected according to their WB pattern, were tested by polymerase chain reaction (PCR) and radioimmunoprecipitation assay (RIPA). Study Design and Methods: In two commercially available WBs, 12 samples wer e confirmed as positive (rgp21+p19+p24) and 174 were interpreted as in determinate (one or two reactivities to these proteins). The primer pa irs used for the PCR allowed the amplification of type I (HTLV-I) or t ype II (HTLV-II) (or both) sequences, The RIPA was performed with two 35S-labeled cell lines: HTLV-I infected HUT 102/82 and HTLV-II-infecte d MoT. Results: Of the 12 positive samples, 11 were classified as HTLV -I-positive and one as HTLV-II-positive. Among the 174 indeterminate s amples, three (WB pattern: rgp21+, p19+, p24-) were HTLV-I positive in PCR (one of them was positive in RIPA also); the other 171 were HTLV negative. Conclusion: In the study of a population in which 97 percent of HTLV infections are due to HTLV-I, these data support the three-pr otein criteria (rgp21; p19, and p24) for a positive blot reading. No H TLV infection was observed when rgp21 did not react, Consequently, p19 and/or p24 band patterns represent false reactivity and do not requir e PCR or RIPA confirmation. To discriminate between false- and true-po sitive results in the absence of MTA-1 or K55 reactivity, PCR and/or R IPA is required only when rgp21 reactivity is associated with one gag band (p19 or p24).