Prevalence of HTLV‐I and HTLV‐II infection in gabon, africa: Comparison of the serological and pcr results

Abstract

A cluster sampling survey was performed in 1989 in Libreville, Gabon, to determine HTLV-I and HTLV-II prevalence and to compare the efficacy of polymerase chain reaction (PCR) and serology in detecting HTLV-I and HTLV-II infections. A total of 322 sera from adults were tested by ELISA and by Western blot (WB). The WB patterns were interpreted according to WHO criteria and those of the manufacturer. PCR analysis using primer pairs in the gag and pol region, with a specific probe for HTLV-I and HTLV-II, was performed on the lymphocytes of the 322 adults. In addition, 134/322 samples were re-tested with tax primers, in a second laboratory. Using WHO criteria, 8/322 (2.5%) samples were positive on WB and 25 were indeterminate; with the criteria of the kit, 26/322 (8.1%) were positive and 7 were indeterminate by WB. By PCR, 13 (4%) samples were positive, including 12 for HTLV-I (3.7%) and one for HTLV-II (0.3%). All 8 seropositive samples (by the WHO criteria) were positive by PCR, as were 4 out of 25 indeterminate samples. Only one out of 289 seronegative samples was positive by PCR. In contrast, only 12/26 positive samples by the kit criteria were confirmed by PCR. These results confirm the relatively high HTLV-I/II seroprevalence observed in Gabon. HTLV-I infection is preponderant, but HTLV-II is also present. The WHO criteria for WB give a better fit with PCR results than the kit criteria for WB. In the absence of a specific confirmatory test and based on the uncommon "seronegative" HTLV-I/II infection, the indication for PCR appears limited to the positive WB samples (to differentiate HTLV-I and II infection) and to the indeterminate WB samples.

Failure to isolate human T cell lymphotropic virus type I and to detect variant-specific genomic sequences by polymerase chain reaction in Melanesians with indeterminate Western immunoblot

“…Moreover, we were unable to isolate HTLV-I and to detect HTLV-I (and HTLV-II) genomic sequences in Melanesians (and Polynesians) with indeterminate Western blots. Similarly, as reported recently, HTLV-I genomic sequences have not been detected in the vast majority of seroindeterminate individuals from Gabon, Africa (Delaporte et al, 1991).…”

“…Indeterminate H T L V -I Western blots are frequently found with sera from Melanesian (Asher et al, 1988;Garruto et al, 1989Garruto et al, , 1990Armstrong et al, 1990;Yanagihara et al, 1990 and African individuals (Ouattara et al, 1986;Constantine & Fox, 1989;Delaporte et al, 1989Delaporte et al, , 1991. Among the remote Hagahai of Papua New Guinea and Melanesians of the Solomon Islands, more than 50 ~o of individuals who are repeatedly reactive to H T L V -I antigens by screening tests, such as ELISA, possess antibodies to only gag-encoded proteins by Western blot analysis (Yanagihara et al, , 1991a.…”

Isolation and molecular characterization of a human T-cell lymphotropic virus type II (HTLV-II), subtype B, from a healthy Pygmy living in a remote area of Cameroon: an ancient origin for HTLV-II in Africa.

“…HTLV-II-like serological markers (not verified by sequencing) in Pygmies in remote areas of Zaire (22,24) and Cameroon (25), who are considered to belong to the oldest ethnic groups in central Africa, having lived in those areas for at least 20,000 years (27,28).…”

Frequency of adult T-cell leukaemia/lymphoma and HTLV-I in Ibadan, Nigeria

“…weak reactivity and sparse banding) suggests the possibility that a mixutre of true HTLV-I positivity and cross reactivity with a related virus may explain this paradox. An HTLV-II-like virus which has been recently reported in West Africa could be a candidate (Delaporte et al, 1991). Alternatively, sera from Africa have been notoriously difficult to reliably test because of high rates of positivity (Biggar et al, 1985).…”