New Virus May Have Come from Monkeys, Experts Say
WASHINGTON Two new retroviruses never before seen in humans have turned up among people who regularly hunt monkeys in Cameroon, researchers reported Friday.
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 two new viruses are called human T-lymphotropic virus types 3 and 4 or HTLV-3 and HTLV-4. They are closely related to two 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 U.S. 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 at least six different simian retroviruses had infected 13 of the people.
"Two hunters were infected with two previously unknown HTLV viruses. One person was infected with HTLV-3, which is genetically similar to a simian virus, STLV-3, and represents the first documented human infection with this virus," the researchers told the 12th Annual Retrovirus Conference being held in Boston.
"The second 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, the CDC said.