Comparison of immunofluorescence, enzyme immunoassay, and Western blot (immunoblot) methods for detection of antibody to human T-cell leukemia virus type I

Abstract

A total of 3,349 serum samples were screened by the immunofluorescence (IF) method for antibody to human T-cell leukemia virus type I (HTLV-I). Only 9 of 2,409 specimens from selected individuals, blood bank donors, patients with encephalitis-meningitis, and human immunodeficiency virus antibody-positive homosexual or bisexual men were reactive by IF. In addition, 940 serum samples from intravenous drug abusers were tested by IF and also by an HTLV-I enzyme immunoassay (EIA) method. Of these, 222 (24%) were positive for both HTLV-I and HTLV-II antigens by IF, and 191 of these 222 were also reactive in the HTLV-I EIA. Of the 31 IF-positive, EIA-negative serum samples, 20 exhibited optical density readings greater than or equal to 70% of the positive cutoff in the EIA, and 29 samples reacted with 1 or more bands in the Western blot (immunoblot) test. An additional 10 specimens that were EIA negative reacted only with HTLV-I by IF. Differences in staining morphology and in reactions on HTLV-I and HTLV-II antigens before and after absorption of the serum specimens with HTLV-I and HTLV-II-infected cell pellets revealed six distinct serological patterns by IF. These results indicate that infections by HTLV-I or by another closely related retrovirus(es) occur in California. Further studies utilizing statistically valid sampling methods are needed to estimate true prevalence rates among various groups. IF and Western blot tests should supplement the EIA method to maximize sensitivity and specificity of test procedures.

Comparison of six commercial human T-cell lymphotropic virus type I (HTLV-I) enzyme immunoassay kits for detection of antibody to HTLV-I and -II

“…A relatively high rate of antibody to human T-cell lymphotropic virus type II (HTLV-II) has been demonstrated in intravenous drug user (IVDU) populations in various regions in the United States, including California (3,4,8,9). An HTLV-I enzyme immunoassay (EIA) screening test is usually used to test for antibody, but HTLV-T and HTLV-II share cross-reacting antigens, and the EIA can not differentiate antibodies to these two agents.…”

“…The kits were evaluated with a panel of 213 serum or plasma samples which were screened by immunofluorescence assay (IFA) on both HTLV-Iand HTLV-II-infected cells as described previously (3). The panel consisted of 35 IFA-negative and 110 IFA-positive samples from patients attending drug treatment centers and 66 IFA-negative and 2 IFA-positive samples from blood bank donors.…”

Sensitivities of radioimmunoprecipitation assay and PCR for detection of human T-lymphotropic type II infection

“…IFA. All specimens were reacted at a 1:10 dilution on HTLV-I (MT2)and HTLV-II (clone 19)-infected slides as described previously (4). A sample must react specifically with both antigens to be considered positive.…”

Detection and differentiation of antibodies to human T-cell lymphotropic virus types I and II by the immunofluorescence method

“…We use the enzyme immunoassay (EIA) and the indirect immunofluorescence (IF) test to screen sera for antibody to human T-cell lymphotropic virus type I and type II (HTLV-I and HTLV-II). The Western immunoblot (WB) and the radioimmunoprecipitation assay (RIPA) are employed when the results of the EIA and IF screening methods do not agree (4). Because HTLV-I and HTLV-II have approximately 60% genetic homology, these serologic methods detect antibody to both types.…”