Peripheral blood mononuclear cells (PBMC) from three adult male squirrel monkeys (Saïmiri sciureus) were transformed by human T-cell leukemia/lymphoma virus type I (HTLV-I) by cocultivation with lethally irradiated human MT-2 cells. Three permanent monkey T-cell lines producing HTLV-I were obtained and characterized. Six weeks after inoculation seroconversion was observed in three of three monkeys inoculated with autologous transformed T cells and in two of three monkeys receiving homologous cells. Proviral DNA was detected in their PBMC at various times after inoculation, with the highest proviral load and antibody titers being found in monkeys infected with homologous cells. Monkeys inoculated with heterologous MT-2 cells did not seroconvert, and HTLV-I provirus was detected only transiently in their PBMC. To determine whether in vitro and in vivo HTLV-I infection of squirrel monkey cells led to a selection of monkey-adapted viral mutants, comparative sequencing of the proviral gp21 env between ex vivo monkey HTLV-I-infected PBMC, the inoculum, and MT-2 cells was done and no significant differences were detected. The squirrel monkey, which is naturally free of simian T-cell leukemia/ lymphoma virus, thus appears to be a suitable model for evaluating HTLV-I candidate vaccines and for studying the pathogenesis of HTLV-I.

To determine the epidemiological characteristics of human T cell leukemia/lymphoma virus type I (HTLV‐I) infection in the endemic village of Maripasoula, French Guiana, 1,614 persons (83.2% of the population) aged 2 to 91 years (mean age 21) were studied from November 1994 through April 1995. Plasma samples were screened by an HTLV‐I ELISA and an IFA test (on MT2 cells), and positive samples were tested by an HTLV‐I and ‐II type‐specific Western blot. Overall seropositivity in the village was 6.7%, but HTLV‐I infection was restricted to 3 of 6 ethnic groups, including the Noir‐Marron (descendants of escaped African slaves, 8%), the Creoles (4.1%) and those of mixed Noir Marron/other ethnicity (3.6%). In the Noir‐Marron population of 1,222 persons, including 606 men and 616 women and representing 76% of those tested, HTLV‐I seroprevalence increased significantly with age in both sexes, reaching 40% in women older than 50 years. Univariate risk factors for HTLV‐I seropositivity in women included older age, more pregnancies, more live births and a history of hospitalization. A cross‐sectional analysis of sexual partners demonstrated an excess of discordant female HTLV‐I+/male HTLV‐I− couples, indicating preferential male‐to‐female sexual transmission. The demonstration of 11 HTLV‐I‐seropositive children aged less than 15 years, of whom 9 had a seropositive mother, suggested maternal–child HTLV‐I transmission. Our results demonstrate a very high seroprevalence of HTLV‐I in this South American population descended from African slaves, probably due to high rates of mother‐to‐child and sexual transmission within this rather isolated group. Int. J. Cancer 76:331–336, 1998.© 1998 Wiley‐Liss, Inc.

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