Use of a generic polymerase chain reaction assay detecting human T‐lymphotropic virus (HTLV) types I, II and divergent simian strains in the evaluation of individuals with indeterminate HTLV serology

Abstract

In countries with a low prevalence of human T-lymphotropic virus (HTLV) infection, indeterminate HTLV serologies are a major problem in blood bank screening because of the uncertainties about infection in these cases. The recent discovery of two new types of simian T-lymphotropic viruses (STLV), which give an HTLV-indeterminate serology, raises the question whether indeterminate serologies in humans may be linked to new types of HTLV. Starting from a Tax sequence alignment of all available primate T-cell lymphotropic virus strains (PTLV), including the two new types STLV-PH969 and STLV-PP1664, we developed generic and type-specific nested polymerase chain reactions (PCRs). The generic PCR proved to be highly sensitive and cross-reactive for all four types of PTLV, while the discriminatory PCRs had a high sensitivity and a specificity of 100%. There was no cross-reactivity with human immunodeficiency virus (HIV), ensuring correct interpretation of results from coinfected patients. Among the 77 serologically indeterminate samples tested, 6 were found to be HTLV-1 PCR positive and 1 was HTLV-II PCR positive. Sequencing of one of the HTLV-I PCR positives excluded PCR contamination, and revealed a divergent type of HTLV-I. The majority of the seroindeterminate samples (91%) were however HTLV-PCR negative, and no new types of HTLV were found. This new assay can identify otherwise undetected HTLV-I or HTLV-II infections and is a useful tool of screening for new types of HTLV among seroindeterminate samples.

Identification in gelada baboons (Theropithecus gelada) of a distinct simian T-cell lymphotropic virus type 3 with a broad range of Western blot reactivity

“…HTLV-1, HTLV-2 and HTLV-indeterminate WB profiles have all been observed in Ethiopian populations (Buckner et al, 1992;Vrielink et al, 1995), but it is not known if any of these reactive samples are associated with STLV-3-like infections. While limited studies of 24 African and 325 non-African human specimens with HTLV-seroindeterminate WB results have detected no STLV-3-like infection (Busch et al, 2000;Vandamme et al, 1997), additional studies of larger numbers of human samples with not only indeterminate but also HTLV-1-and -2-like WB profiles will be necessary to assess fully the rate of infection with STLV-3like viruses. Our finding of one STLV-3-infected gelada baboon with an HTLV-1-like WB profile and a previous report of an STLV-1-infected baboon with an HTLV-2-like serotype (Mahieux et al, 2000) also raises questions about the accuracy of viral typing of PTLV infections by the currently used HTLV-1-and HTLV-2-type-specific Env peptides spiked onto HTLV-1 WB strips.…”

“…Unlike STLV-1 and STLV-2, which are believed to be the simian equivalents of HTLV-1 and HTLV-2, it is not known whether STLV-3-like variants naturally infect humans. Limited testing of people with indeterminate HTLV serological results has found no evidence of STLV-3-like infections (Busch et al, 2000;Vandamme et al, 1997). However, phylogenetic studies of STLV-1 and HTLV-1 suggesting the occurrence of multiple interspecies transmissions of STLV (Gessain et al, 2002;Mahieux et al, 1998;Meertens et al, 2001;Slattery et al, 1999), combined with the ability of STLV-3 to grow in human cells in vitro (Goubau et al, 1994), both suggest that humans may be at risk for cross-species infections with STLV-3.…”

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

“…DNA was isolated from frozen whole blood of serologically indeterminate samples and its integrity was confirmed by optimised PCR amplification of glyceraldehyde 3‐phosphate dehydrogenase (GAPDH) using commercially available primers. Samples were tested for the presence of HTLV‐1 DNA by PCR as previously described .…”

African Origin of Human T-Lymphotropic Virus Type 2 (HTLV-2) Supported by a Potential New HTLV-2d Subtype in Congolese Bambuti Efe Pygmies

“…The third HTLV screening-positive serum was indeterminate on the Western blot but proved to be HTLV-1 by ELISA and by PCR (Fig. 1, lane 12) (32,86). Nine other screening-negative samples were indeterminate on Western blots but negative with both ELISA and PCR.…”