Sensitivity and specificity of a recombinant transmembrane glycoprotein (rgp21)-spiked western immunoblot for serological confirmation of human T-cell lymphotropic virus type I and type II infections

Abstract

Serum specimens (n = 2,712) obtained from individuals residing in diverse geographic regions and categorized as seropositive (n = 122), seroindeterminate (n = 523), or seronegative (n = 2,067) for human T-cell lymphotropic virus (HTLV) infection in accordance with U.S. Public Health Service guidelines were retested by recombinant transmembrane protein (rgp2l)-spiked Western immunoblotting. Of the 122 HTLV-positive specimens, those from 85 of 85 (100%) U.S. blood donors, 2 of 2 (100%) Brazilians, 1 of 2 (50%) Indonesians, 14 of 14 (100%) Solomon Islanders, and 18 of 19 (95%) Papua New Guineans reacted with rgp2l, yielding an overall sensitivity of 98% (120 of 122). Specimens from individuals whose infections were confirmed to be HTLV type I or HTLV type II by the polymerase chain reaction assay reacted equally well with rgp2l. Of the 523 HTLV-indeterminate specimens, those from 21 of 379 (5.5%) U.S. blood donors, 3 of 6 (50%) Brazilians, 10 of 23 (44%) Ugandans, 8 of 49 (16%) Indonesians, 4 of 36 (11%) Solomon Islanders, and 5 of 30 (17%) Papua New Guineans reacted with rgp2l. None of these 51 specimens reacted with native gp46 and/or gp61/68 in a radioimmunoprecipitation assay, suggesting a false-positive reaction (9.75%). Of the 2,067 HTLV-negative specimens, 12 reacted with rgp2l, yielding a false-positivity rate of 0.6%. These data indicate that while detection of rgp2l is highly sensitive, it can yield false-positive results. Thus, specimens exhibiting reactivity with rgp2l in the absence of reactivity with native gp46 and/or gp61/68 by Western blot should be tested further by a radioimmunoprecipitation assay to verify HTLV type I or type II infection.

Enhanced specificity of truncated transmembrane protein for serologic confirmation of human T-cell lymphotropic virus type 1 (HTLV-1) and HTLV-2 infections by western blot (immunoblot) assay containing recombinant envelope glycoproteins

“…Modified WB spiked with GD21-I results in enhanced specificity. We and others have previously demonstrated that the use of r21e in WB assays results in false-positive results (12,13), and therefore, an assay based on r21e detection alone could not be used as a sole confirmatory test in blood donor settings (4). The specificity of the modified HTLV WB 2.4 assay was next determined in specimens which were considered HTLV-1/2 positive (p24 and r21e positive) or HTLV indeterminate (any reactivity not fulfilling the criteria of seropositivity) by the standard WB assay.…”

“…The sensitivities of Western blot (WB; immunoblot) assays for the detection of antibodies to envelope proteins of HTLVs have been substantially enhanced by the addition of the recombinant transmembrane protein r21e, which can detect antibodies in all HTLV-1-and HTLV-2infected individuals (2,17). The added sensitivity of r21espiked WB assays, however, has resulted in an increased proportion of false-positive results (12,13). Because of the lack of absolute specificity of this assay, it is recommended that the p21e WB assay not be used as a confirmatory test for the notification of blood donors (12).…”

Synthetic Seed Preparation, Germination and Plantlet Regeneration of Litchi (<i>Litchi chinensis</i> Sonn.)

“…Subsequently, the germinating somatic embryos (5 per flask) were transferred to 250 ml Erlenmeyer flasks, each with 50 ml liquid medium containing half-strength B5 macrosalts with full-strength MS microsalts, iron-EDTA and organics, 2.74 mM L-glutamine (added before pH adjustment) and 3% (w/v) sucrose. Glutamine is known to play a regulatory as well as a nutritive role in somatic embryo maturation and during autoclaving it is converted to 5-oxoproline [44]. The cultures were maintained in a 16 h photoperiod as described earlier.…”

No Proof of HTLV‐I/II in Intravenous Drug Abusers with a High Rate of HIV‐1 Infection in Central Thailand

“…1). Since indeterminate blots were recommended not to be used for diagnosis of HTLV-I/II infecton because of nonspecific reaction of uninfected sera (15), none of the samples were classified as HTLV-II positive. All the reference sera from HTLV-II-infected IVDAs from South Vietnam and HTLV-I-infected individuals from the southern part of Japan were reactive with HTLV-II and HTLV-I in this Western blot, respectively (data not shown).…”