Comparison of four HTLV-I and HTLV-I + II ELISAs.

BACKGROUND: Various countries require blood donor screening using assays applying specific HTLV-I and HTLV-II antigens. We evaluated the sensitivity and specificity of 4 anti-HTLV-I + II ELISAs (Abbott, Murex, Organon Teknika and Ortho). METHODS: Panel A consisted of HTLV-I-positive individuals (n = 41), panel B of Mixed Titer Performance Panel 204 (Boston Biomedica Inc. panels C and D of dilution series from HTLV-I-positive (n= 30) and HTLV-II-positive (n =20) individuals and panel E of sera from first-time blood donors (n = 1,055). RESULTS: In HTLV-I- and -II-positive samples, a sensitivity of 100% could be observed in all 4 ELISAs. In diluted HTLV-I- and -II-positive samples, probit analysis revealed that the Murex assay had the highest analytical sensitivity, followed by the ELISAs from Ortho, Abbott and Organon Teknika. In specimens from first-time donors, a specificity of 100% was observed in ELISAs from Murex, Organon Teknika and Ortho, and of 99.7% in the assay from Abbott. CONCLUSION: The 4 anti-HTLV-I + II ELISAs studied were appropriate as screening tests.

Identification of a type-specific protein that differentiates serologically between human T cell lymphotropic virus types I and II.

The 24-kDa band formed when sera of humans infected with human T cell lymphotropic virus type I (HTLV-1) were reacted with HTLV-I lysates in conventional Western blot (WB) assays was found to be composed of two immunologically unrelated proteins of 24- and 23-kDa. p24, but not p23, carries epitopes shared by the major core proteins of the other known transactivating C-type retroviruses. p23 is unrelated immunologically to the env and tax HTLV-I products but partly cross-reacts with HTLV-I p19. All HTLV-I and simian T cell leukemia virus type I sera tested reacted with p23. Reactivity with p23 was seen with some HTLV-I sera that did not react or reacted weakly with HTLV-I p24. No reactivity with p23 was seen among the 51 human HTLV-II sera tested nor among a large panel of control sera. Because of its type-specificity and strong immunogenicity, p23 provides a reliable serologic marker for the diagnosis of HTLV-I infection and for distinguishing between HTLV-I and -II.

Discrimination of human T-lymphotropic virus type-I and type-II infections by synthetic peptides representing structural epitopes from the envelope glycoproteins.

Synthetic peptides representing the immunodominant structural motifs of the envelope region of human T-lymphotropic virus types I (HTLV-I) (Env-1(191-214) and Env-5(242-257)) and II (HTLV-II) (Env-20(85-102 and Env-2(187-209)) were used to develop an enzyme immunoassay that could discriminate between HTLV-I and HTLV-II. Serum specimens from individuals whose infections were confirmed and typed by means of the polymerase chain reaction (PCR) were used to determine the sensitivity and specificity of the new assay. When 73 PCR-confirmed HTLV-I specimens were tested with the HTLV-I peptides, the absorbance values for 71 (97.3%) were at least two times higher than the values obtained with the HTLV-II peptides; these samples thus were classified as HTLV-I. Two specimens reacted with all the peptides and, therefore, could not be typed. Conversely, when 59 PCR-confirmed HTLV-II specimens were tested with the HTLV-II peptides, 55 (93%) produced high absorbance values and were typed as HTLV-II; 4 specimens could not be typed. None of the specimens was incorrectly typed; hence, the specificity of this assay was 100%. When this assay was compared with other HTLV immunoassays, the degrees of sensitivity and specificity were similar. The main advantage of this new assay is that synthetic peptides representing variant sequences can easily be added as new variant HTLV strains are identified.