Chinese scientists have identified what they say is the most complex HIV ever discovered, in the blood of a long-distance truck driver from Myanmar.

Scientists from the Kunming Institute of Zoology sequenced genetic materials extracted from the driver's blood after he entered China from a border checkpoint in Yunnan province.

In the sample, all nine genes of the HIV had been reprogrammed in a more sophisticated way than the most complex HIV found to date.

"Reprogramming only occurs when the carrier catches different types of virus repeatedly. Gene recombination is possible when different types of virus exist in his blood at the same time," said Zhou Yanheng, a PhD student at the institute who published the discovery in the US journal AIDS Research and Human Retroviruses.

The HIV takes various forms that can recombine with each other and develop into a novel virus.

"The complexity of the newly found virus does not necessarily mean that the virus is becoming more infectious or more prevalent, but it may reflect the epidemic of HIV in the border regions of Yunnan province," Zhou said.

"The constant and regular movement of high-risk groups between China and Myanmar is increasing the bidirectional spread of HIV between these two countries and thus contributes to the genetic diversity of the virus," he said.

Most border regions have been hard hit by HIV due to the geographical location and relatively high number of high-risk groups, according to He Xiong, an expert from the Beijing branch of the Chinese Center for Disease Control and Prevention.

"The situation is especially crucial in mountain regions like the China-Nepal border, where land transportation is almost the only means of transportation," He said.

Some drivers spend months driving across hundreds of kilometers of depopulated areas with only several stops in the middle where they can rest.

"Despite the fact that we have been distributing brochures to the drivers, many of them still have unprotected sex.

"The attempt to educate sex workers is also ineffective, because they would agree not to use condoms to make more money," He said.

chengyingqi@chinadaily.com.cn