People who lived in the Chilean Andes a millennium ago were cursed with the same virus that afflicts many modern Japanese people, a new study suggests. The virus, associated with leukemia and lymphoma, appears to have traveled to the New World with its early settlers, who are believed to have come from northern Asia via the Bering Land Bridge more than 12,000 years ago.
Human T cell lymphotropic virus-type I (HTLV-I), a blood-borne retrovirus, causes leukemia in about 3% of carriers. It's most common in parts of southern Japan, where it infects at least 4% of the population. Isolated groups in Colombia and Chile also harbor HTLV-I, but researchers couldn't be sure whether it had arrived with ancient Americans or later with European colonizers.
To unravel the virus's origins, Japanese and Chilean researchers led by epidemiologist Kazuo Tajima of the Aichi Cancer Center Research Institute in Kanokoden, Japan, examined 104 mummies buried 1200 to 1500 years ago and preserved by the dry Atacama desert.They were able to get DNA from only two mummies; they found shards of HTLV-I virus in the bones of one. After sequencing the DNA, the researchers report in the December issue of Nature Genetics, they found that it closely matched that of HTLV-I virus in modern Japan. Because scientists assume that the virus originated in Asia, the finding not only demonstrates its venerability but adds to evidence that northern Asians peopled South America, says evolutionary geneticist Kenneth Kidd of Yale University: "Our pathogens have been around as long as we have."
