Important note: Information in this article was accurate in 2005. The state of the art may have changed since the publication date.
A ProMED-mail post <http://www.promedmail.org>
ProMED-mail is a program of the International Society for Infectious Diseases <http://www.isid.org>
Date: Sat 26 Feb 2005
From: ProMED-mail <promed@promedmail.org>
Source: Reuters News, Fri 25 Feb 2005 [edited]
<http://www.alertnet.org/thenews/newsdesk/N25165374.htm>
Cameroon: 2 new human T-cell lymphotropic viruses isolated
2 new retroviruses never before seen in humans have turned up among people who regularly hunt monkeys in Cameroon, researchers reported on Fri 25 Feb 2005. Like the AIDS virus, these viruses insert their genetic material directly into cells and perhaps even into a person's or animal's chromosomes. Closely related versions of the viruses cause leukemia, inflammatory, and neurological diseases.
The 2 new viruses are called human T-lymphotropic virus types 3 & 4 (abbreviated as HTLV-3 and HTLV-4). They are closely related to 2 known viruses called HTLV-1 and HTLV-2, which experts believe were transmitted to people, like HIV, from monkeys and apes.
"Because HIV originated as a cross-species infection from a non-human primate virus, the question was how much cross-species retrovirus infections are occurring, and what are the consequences of these infections," said Walid Hemeine of the US Centers for Disease Control and Prevention, who led the study.
They examined blood samples from 930 Cameroonians who had handled or eaten bush meat (monkeys or apes hunted for food). They used antibody screening and genetic analysis to find that at least 6 different simian retroviruses had infected 13 of the people. "2 hunters were infected with 2 previously unknown HTLV viruses. One person was infected with HTLV-3, which is genetically similar to a simian virus, STLV-3, and represents the 1st documented human infection with this virus," the researchers told the 12th Annual Retrovirus Conference being held in Boston.
"The 2nd hunter was infected with HTLV-4, a virus distinct from all previously known human or simian T-lymphotropic viruses. It's totally new, so we don't know any other simian virus that is related to it," Hemeine said in a telephone interview.
Now the team, which includes researchers at Johns Hopkins University in Baltimore, plans to look more extensively in Central Africa for the virus, Hemeine said. "They could be more widespread than we think they are," he said. Hemeine said up to 25 million people globally are infected with HTLV-1 and 2. Currently, specialized tests are needed to find the viruses, he said. "It's a new virus. You pause, you say, where is this virus coming from. I don't think you should be taking it lightly," Hemeine said. After infecting one person, simian viruses often spread from person to person through sex, mother-to-child transmission, and other exchanges of blood and body fluids. Like HIV, the incubation period for HTLV viruses to cause disease can last decades, CDC said.
[byline: Maggie Fox]
ProMED-mail <promed@promedmail.org>
[The viruses originally known as human T-lymphotropic viruses have been re-designated primate T-lymphotropic viruses in recognition of their prevalence in non-human primates as well as humans. Human T-lymphotropic virus 1 and simian T-lymphotropic virus 1 are closely related and now ranked as members of the same virus species: primate T-lymphotropic virus 1. Likewise, Human T-lymphotropic virus 2 and simian T-lymphotropic 2 virus are ranked now as members of the same species: primate T-lymphotropic virus 2. Simian T-lymphotropic virus 3 was the sole member of the species, primate T-lymphotropic virus 3, until its human counterpart was discovered in Cameroon as described above. Human T-lymphotropic virus 4 is an entirely new virus, and its simian counterpart has still to be detected. All the primate T-lymphotropic viruses, together with the species bovine leukemia virus, make up the genus Deltaretrovirus, one of the 7 genera that comprise the family of reverse-transcribing viruses know as the Retroviridae.
The deltaretroviruses are transmitted horizontally, and no endogenous counterparts are known. So far, they have been found only in bovines and primates. They are associated with B- or T-cell leukemias or lymphomas, and neurological disease (tropical spastic paraparesis or HTLV-associated myopathy).
HTLV-1 was isolated 1st from a cell line derived from splenic cells taken from a patient suffering from a hairy cell leukemia, now considered to be a fortuitous association. No oncogene-containing members of the genus are known. HTLV-2 is known now to be endemic among several Amerindian populations in North, Central and South America. In industrialized countries, HTLV-2 is prevalent among drug abusers and is spread by contaminated needles and by heterosexual transmission. In the developing world, breast-feeding may be the predominant route of transmission. Biologically, the HTLVs differ from HIV in their greater genetic stability and their characteristic patterns of geographic distribution.
Previously, it was thought that the present distribution of HTLV 2 in the world reflected its possible introduction into the New world at the time of the initial settlement of the American continent by the ancestors of the present day native Americans some 20 000 to 40 000 years ago, followed by more recent dissemination from one or a few centers. It seems more likely now, in the light of the above evidence, that all 4 primate T-lymphotropic viruses were transmitted to humans from African primates. - Mod.CP]
[see also:
2003
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Intl Congr Infect Dis - Mexico (Cancun): 4-7 Mar 2004 20031105.2744
2001
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Simian foamy virus, humans - Canada 20010630.1245
2000
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HTLV-II, brain disorder - Brazil 20000820.1382]
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