14th Conference on Retroviruses and Opportunistic Infections Los Angeles, California - February 25-28, 2007

Conf Retrovir Opportunistic Infect 2007 Feb 25-28;14: (abstract no. 6)

William Switzer
CDC, Atlanta, GA, US

BACKGROUND: Primate T-lymphotropic viruses (PTLV) are delta-retroviruses composed of 3 distinct groups (PTLV-1, -2, -3). PTLV-1 and PTLV-2 include both human T-lymphotropic viruses types 1 and 2 (HTLV-1 and HTLV-2) and their simian analogs (STLV-1 and STLV-2, respectively), while PTLV-3 to date comprises only simian viruses. Like HIV, HTLV has spread globally to at least 22 million persons. HTLV-1 causes severe neurological and lymphoproliferative diseases in 2 to 5% of infected persons. While HTLV-1 diversity appears to have resulted from multiple cross-species transmissions of STLV-1, little is known whether contact between humans and STLV-infected nonhuman primates continues to contribute to the emergence of novel HTLV. We investigated the diversity of HTLV in central Africans reporting contact with NHP blood through hunting, butchering, and pet-keeping. Plasma samples were screened for HTLV antibodies using enzyme immunoassay and Western blot assays. Sequences from several viral regions were polymerase chain reaction (PCR)-amplified from peripheral blood lymphocyte DNA of Western blot reactive persons. We show that this population is infected with a wide variety of HTLV, including 2 novel retroviruses: HTLV-4 is the first member of a new phylogenetic lineage that is distinct from all known HTLV and STLV; HTLV-3 falls within the phylogenetic diversity of STLV-3, a group not previously seen in humans. The recent report of a second HTLV-3 in a Pygmy from Cameroon suggests that HTLV-3 infection may not be a rare event. We also document human infections with different STLV-1-like viruses.

CONCLUSIONS: These results demonstrate greater HTLV diversity than previously recognized and suggest ongoing STLV transmission in humans exposed to nonhuman primates. Expanded surveillance and longitudinal clinical studies are needed to better define the epidemiology and public health importance of HTLV-3 and HTLV-4 infections.

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2007-02-25
6

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