Human T-Cell Lymphotropic Virus Type 1 Gag Indeterminate Western Blot Patterns in Central Africa: Relationship toPlasmodium falciparumInfection

Abstract

To gain insight on the significance of human T-cell lymphotropic virus type 1 (HTLV-1) indeterminate serological reactivities, we studied villagers of South Cameroon, focusing on a frequent and specific HTLV-1 Gag indeterminate profile (HGIP) pattern (gag p19, p26, p28, and p30 without p24 or Env gp21 and gp46). Among the 102 sera studied, 29 from all age groups had a stable HGIP pattern over a period of 4 years. There was no epidemiological evidence for sexual or vertical transmission of HGIP. Seventy-five percent of HGIP sera reacted positively on MT2 HTLV-1-infected cells by immunofluorescence assay. However, we could not isolate any HTLV-1 virus or detect the presence of p19 Gag protein in cultures of peripheral blood mononuclear cells obtained from individuals with strong HGIP reactivity. PCR experiments conducted with primers for HTLV-1 and HTLV-2 (HTLV-1/2 primers) encompassing different regions of the virus did not yield HTLV-1/2 proviral sequences from individuals with HGIP. Using 11 peptides corresponding to HTLV-1 or HTLV-2 immunodominant B epitopes in an enzyme-linked immunosorbent assay, one epitope corresponding to the Gag p19 carboxyl terminus was identified in 75% of HGIP sera, while it was recognized by only 41% of confirmed HTLV-1-positive sera. A positive correlation between HTLV-1 optical density values and titers of antibody to Plasmodium falciparum was also demonstrated. Finally, passage of sera through a P. falciparum-infected erythrocyte-coupled column was shown to specifically abrogate HGIP reactivity but not the HTLV-1 pattern, suggesting the existence of cross-reactivity between HTLV-1 Gag proteins and malaria-derived antigens. These data suggest that in Central Africa, this frequent and specific Western blot is not caused by HTLV-1 infection but could instead be associated with P. falciparum infection.

Molecular characterization of human T‐cell lymphotropic virus type 2 (HTLV‐II) from people living in urban areas of Sao Paulo city: Evidence of multiple subtypes circulation

“…To differentiate HTLV-I and HTLV-II infections, RFLP analysis of amplified product of a Tax region was carried out as previously described elsewhere , using primers specific for this region of both HTLV-I and HTLV-II genomes. The betaglobin gene was studied to ensure that all extracted DNAs were amplifiable using primers PC04 and GH20 [Mahieux et al, 2000].…”

Western blot seroindeterminate individuals for Human T-lymphotropic Virus 1/2 (HTLV-1/2) in Fortaleza (Brazil): a serological and molecular diagnostic and epidemiological approach

“…There is however variation of prevalence depending on the geographic area and the population studied. While in Europe and USA the prevalence is low, in tropical areas it reaches higher values [4,5]. Lal et al [16] analyzed 267,650 samples from blood donors, among which 379 (0.14%) were WB seroindeterminate.…”

“…Blood banks worldwide are thus faced with blood donor candidates exhibiting a seroindeterminate Western blot (WB) profile. This is mainly reported in tropical and in some temperate regions endemic for HTLV-1/2 infection, and less frequently in northern countries, where prevalence of HTLV-1/2 is very low [4,5].…”

Seroprevalence of HTLV‐1 and HTLV‐2 amongst mothers and children in Malawi within the context of a systematic review and meta‐analysis of HTLV seroprevalence in Africa

“…None of the HTLV‐positive cases were hepatitis C or HIV positive. High levels of HTLV intermediate screening results are commonly seen in African sera ; only one of the 18 tested indeterminate samples could be resolved by DNA testing. Ten of 12 HTLV‐positive children had HTLV‐negative mothers.…”