Unusual finding of HTLV-I infection among Amazonian Amerindians

Human T-cell lymphotropic virus type II is a retrovirus endemic in Amerindian communities throughout the American continent, although some Amerindian groups that apparently emerged from the same ethnic root as HTLV-II carriers do not secrete antibodies against the virus and show very low prevalence for human T-cell lymphotropic virus type I. In this study, sera from 487 Amazonian amerinds were screened for HTLV type I and II antibody by the gelatin particle agglutination assay and ELISA and confirmed by Western blot and indirect immunofluorescence assay. None was positive for HTLV type II. One young healthy male of Wai?pi ethnicity was reactive with HTLV-I and was confirmed by Western blot assay and indirect immunofluorescence test. The absence of HTLV type II infection among these Amerindian communities would suggest a behavior pattern distinct from other groups in the American continent. Also, the very low prevalence of HTLV type I infection among these ethnic groups probably indicates contamination by blood transfusion (external transmission route).     

Seroindeterminate patterns and seroconversions to human T-lymphotropic virus type I positivity in blood donors from Martinique, French West Indies

BACKGROUND: Screening for human T-lymphotropic virus type I (HTLV-I) antibodies in volunteer blood donors has been systematic in the French West Indies since 1989. Western blot-indeterminate results are commonly obtained. The significance of these indeterminate serologic patterns in HTLV-I-endemic areas is still unclear. STUDY DESIGN AND METHODS: During a 2-year period, 9759 blood donors were tested for HTLV-I antibodies. The epidemiologic features of HTLV-I-seropositive, -seroindeterminate, and -seronegative donors were compared. A lookback investigation was performed for the HTLV-I-seropositive donors, and the HTLV-I-seroindeterminate individuals were followed up. RESULTS: Thirty-nine donors (0.4%) were HTLV-I seropositive and 49 (0.5%) were seroindeterminate. The age and sex ratio characteristics of the seroindeterminate donors are divergent from those of the HTLV-I-seropositive group and are more like those of the seronegative population. However, during the study period, three cases of seroconversion after an initial seroindeterminate profile were reported. Two cases were detected through follow-up of 38 HTLV-I-seroindeterminate donors over a mean of 8 months (2-24 months). The third seroconverter belonged to the HTLV-I-seropositive group and was identified through lookback investigation. This case is atypical, with p19 reactivity for several months before HTLV-I seropositivity. CONCLUSION: These findings indicate that, although HTLV-I-seroindeterminate donors mainly are HTLV-I-noninfected, the rate of seroconversion in a repeat blood donor population from an endemic region must be taken into consideration. Moreover, the case of delayed seroconversion observed in this study suggests the difficulty of counseling seroindeterminate blood donors in endemic regions.     

Evaluation of a combined lysate/recombinant antigen anti-HTLV-I/II ELISA in high and low endemic areas of HTLV-I/II infection

SUMMARY. The Wellcozyme HTLV-I/II ELISA (Murex Diagnostics) was evaluated in 7800 samples of various serum panels. Repeat reactivity was found by Wellcozyme in (A) 1/2181 (0.05%) Dutch blood donors, (B) 44/3036 (1.4%) Curaçao (Caribbean area) blood donors, (C) 46/2533 (1.8%) individuals of different Ethiopian population subsets, (D) 30/30 (100%) confirmed anti-HTLV-I positive samples and (E) 20/20 (100%) HTLV-II PCR-positive samples. All 91 Wellcozyme-positive samples were tested for confirmation by Western blot (WB, Diagnostic Biotechnology). Among Wellcozyme HTLV-I/II ELISA-positive individuals, HTLV-I/II WB positivity was found in 0/1 Dutch blood donors, 40/44 (88.9%) Curaçao blood donors and 20/46 (43.5%) Ethiopian individuals. HTLV-I positivity was found in 40 (1.3%) WB-positive Curaçao blood donors and in 9 (0.35%) Ethiopian individuals. HTLV-II positivity was found in 11 (0.43%) WB-positive Ethiopian individuals. The Wellcozyme HTLV-I/II ELISA had a specificity of 99.95% in Dutch blood donors and a sensitivity of 100% in confirmed HTLV-I- and HTLV-II-positive samples. In Ethiopia 55% of the HTLV-I/II WB-positive individuals were exclusively HTLV-II positive, whereas in Curaçao no HTLV-II infections were found.     

Dual Infection of Rabbits with Human T Cell Lymphotropic Virus Types I and II

Attempts were made to generate a rabbit model of dual infection with human T lymphotropic virus (HTLV) types I and II. Four groups (A, B, C, and D) of three rabbits each were used. Group A was inoculated with the RW-1 cell line coinfected with HTLV-I and HTLV-II and group B was transfused from a dually infected rabbit. Polymerase chain reaction (PCR) using primers specific for the pol region of each virus detected both HTLV-I and HTLV-II in all group A and two group B rabbits, but HTLV-II only in the remaining group B rabbit. Groups C and D already infected with HTLV-I and HTLV-II, respectively, were inoculated with an HTLV-II- or HTLV-I-producing cell line. One group C rabbit became PCR-positive for both viruses but the other five resisted superinfection with the respective viruses. During prolonged observation, three of the six dually infected rabbits converted to single (HTLV-I or HTLV-II) infection. The in vivo dual infection was confirmed by in vitro establishment of a lymphoid cell line coinfected with HTLV-I and HTLV-II. It was also possible to establish coinfected lymphoid cell lines from HTLV-I-infected rabbits by coculture with lethally irradiated HTLV-II-producing cells and vice versa. The mechanism of viral elimination in dually infected rabbits, as well as that of protective immunity against superinfection, remains to be elucidated.     

Spontaneous proliferation of memory (CD45RO+) and naive (CD45RO-) subsets of CD4 cells and CD8 cells in human T lymphotropic virus (HTLV) infection: distinctive patterns for HTLV-I versus HTLV-II.

Systemic lupus erythematosus is associated with the presence of autoantibodies which bind several ribonucleoproteins, including Ro (or SS-A). We have explored the relationship of the HLA-DQ and T cell receptor alleles in patients producing autoantibodies binding the 13-kD carboxyl terminus fragment of the 60-kD Ro and with autoantibodies binding a peptide epitope within this fragment (amino acid residues 480-494). Antibodies binding the 13-kD fragment are more likely to be found in the sera of patients with particular DQA1 and DQB1 alleles, while antibodies binding the epitope at 480-494 are found almost exclusively in the sera of patients with a Bg/II 9.8-kb polymorphism of the T cell receptor beta gene. Meanwhile, in these same patient sera the level of autoantibodies binding the complete 60-kD Ro particle is associated with a distinct pattern of alleles at these same immunoregulatory loci. These data demonstrate that component parts of autoantibody responses may be under genetic control which can be distinguished from the HLA associations characteristic of the response to the intact, complete autoantigen.     

Human T-cell leukemia virus type II infection among high risk groups and its influence on HIV-1 disease progression

The prevalence and the risk factors of the human T-cell leukemia virus type I/II (HTLV-I/II) infection were evaluated among 552 individuals at high risk for HIV-1. HTLV infections showed a low (1.6%) prevalence, were restricted to intravenous drug addicts and were due to HTLV-II alone. Moreover, in order to weigh the influence of HTLV-II on the natural history of HIV-1 infection, the clinical outcome of HIV-1 disease was compared between subjects with and without HTLV-II coinfection. Our findings showed that HTLV-II does not adversely affect the outcome of HIV-1 infection. Infact, a slower disease progression has been recorded in some HTLV-II coinfected subjects.