New strain of HIV emerges along border

Wide range of measures taken to battle infections in Yunnan province and neighboring nations

On Feb 29, 2008, a convoy of long-distance trucks crossed into China from Myanmar. The drivers lined up at the customs house in Jiegao, a border town in southwestern Yunnan province, for a regular HIV/AIDS test, and each was asked to provide 2 to 3 milliliters of blood.

One sample, provided by a 40-year-old driver from Myanmar, was found to be positive for antibodies of HIV - human immunodeficiency virus - but they were unlike any seen before, leading researchers to suspect that it was a previously unknown strain of the virus.

Their suspicions proved correct, based on additional tests conducted recently. "The strain has genetic segments from three subtypes, rather like the combined strands of DNA seen in people of mixed race," says Zheng Yongtang, from the Kunming Institute of Zoology at the Chinese Academy of Sciences, whose team conducted the research.

"Currently, we have no idea how dangerous the new strain is, because the research was based on analysis of ribonucleic acid in the blood, but the strain itself has not been extracted because of the small amount of blood provided for the test," he says.

In 2011, Zheng's team carried out genetic studies on 105 blood samples collected by the Yunnan International Travel Healthcare Center between 2008 and 2010. All the samples belonged to long-distance truck drivers from outside China, mainly from Myanmar.

Sample No 11 was the only one that carried the new strain, which was described as "one of the most complicated strains of HIV-1 ever detected in Myanmar - a recombinant (mix) of three different HIV subtypes", in a recent article in the journal AIDS Research and Human Retroviruses.

Myanmar has one of the highest rates of HIV in Asia. More than 210,000 of its population of 51 million have the virus, according to UNAIDS, the joint United Nations Programme on HIV/AIDS.

Every year, hundreds of long-distance truck convoys travel from Lasio, the largest trading center in northern Myanmar, to Ruili, a major border city in Yunnan. The distance is 187 kilometers, and the journey usually takes about three hours.

The driver who provided the sample that led to the detection of the new HIV strain lives in Lasio, and he says he'd become infected through unprotected sex with a prostitute. Researchers are working to get additional blood samples from the driver for additional tests. The unregulated sex trade thrives in border towns, where large numbers of cross-border drivers congregate, waiting days, sometimes weeks, for a return cargo. The close proximity of large numbers of people from several ethnic groups and different locations means viruses can spread quickly, which may result in a high number of mutant strains, according to Zheng.

"Along with sex workers and drug addicts, long-distance truck drivers in the border region are an emerging high-risk group for HIV/AIDS prevention," he says. "They are also very likely to be in contact with the two other high-risk groups. Their activities may not only help to spread the virus in the border region, but can also result in the genetic diversity of HIV, which poses a challenge to control and prevention work."

Zheng's research suggests that since 2003 the number of "HIV-1 recombination" hot spots has been rising in northern and central Myanmar, as well as in Dehong, a border prefecture in Yunnan.

Zhou Yanheng, the researcher who identified the new strain, says HIV is divided into two main types. HIV-1 originated from a virus found in chimpanzees, and is the primary cause of HIV infection and acquired immune deficiency syndrome, or AIDS. HIV-2 originated from a virus found in monkeys called sooty mangabeys. It is largely confined to West Africa, and is less easily transmitted.

Zhou says the virus contains nine genes and nine subtypes, and Myanmar is being hit by multiple subtypes of HIV-1, including numerous, unique recombinant forms.

The new strain has a long code, 08mLDTD011, which starts with the year the sample was collected (2008), followed by an "m", which represents Myanmar. LDTD stands for "long-distance truck drivers", and the last three numbers - 011 - indicate the number of the blood sample.

The new strain contains 14 "break points" within its genome, a sequence that contains all the genetic information about an individual's DNA, and every cell in the human body has a complete copy of the genome in its nucleus.

"The genomic sequence is very much like a string of colorful Christmas lights; every little bulb has its unique position and their sequence makes each string different from the others. Break points have interrupted the original genetic sequence, rather as if 14 red bulbs were replaced by other colors, yellow or blue. That's how a new strain of HIV is born," Zhou says.

"Although the genomic sequence of this new virus is very complicated, it doesn't mean the virus itself is highly infectious," she says.

Scientists have been unable to determine how this complex recombinant originated in the trucker's body. Some argue that it emerged via frequent recombination of three subtypes or through related primary recombinant strains in the individual. Others believe the driver acquired the virus from his sexual partners, via direct acquisition of the recombinant or its primary recombinant strain.

"We believe that high-risk behavior involving exposure to, or contact with, high-risk groups in the border region may be responsible for the generation of this complex virus," Zheng says.

"Thus, our discovery of this new strain was an alarm call, a warning that much more attention needs to be paid to this group," he adds.

Yunnan shares a 4,060-km-long border with Myanmar, Laos and Vietnam, and nearly 6 million Chinese live in the area.

Myanmar's border with China is 1,977 km long and is straddled by 13 ethnic groups, many of whom share dialects and social traits. Although those factors facilitate cross-border trade and cultural exchanges, they also present a challenge to the prevention and control of disease.

The Myanmar government has listed sex workers, drug addicts and itinerant traders near the border as high-risk groups. China offers voluntary HIV/AIDS tests to all long-distance truck drivers - mainly men from Laos, Vietnam and Myanmar - at crossing points along the border.

Research by the Kunming Institute of Zoology shows that long-distance truck drivers in the border area have a high risk of exposure, mainly through unprotected sex or by taking drugs via unclean syringes.

HIV/AIDS has been under regular surveillance by the Yunnan Entry-Exit Inspection and Quarantine Bureau since 1991, and in the past five years approximately 30,000 visitors from other countries have had annual health checks - including tests for dengue fever, malaria, venereal disease and HIV/AIDS - at 23 level-one and level-two state entry ports.

"After 2012, we noticed a rise in the number of foreign migrant workers carrying the virus, and about 80 to 90 percent were long-distance truck drivers," says Yang Xuebin, director of the bureau's Health and Quarantine Office.

By 2014, Yunnan had 223 laboratories for the detection of HIV/AIDS, along with 201 surveillance centers and 309 voluntary consulting offices. The number of surveillance centers in the border region has risen to 45 from 15 in 2005, according to the HIV/AIDS Prevention Bureau of the Yunnan Center for Disease Control and Prevention.

The bureau's statistics show that more than 31,000 couples are in cross-border marriages, with partners coming from Vietnam, Myanmar, Laos or Thailand. Although the population in the region's eight prefectures accounts for nearly 40 percent of Yunnan's 46 million people, the region itself accounts for 60 percent of the provincial population with HIV/AIDS.

At the end of last year, the bureau launched an HIV/AIDS prevention and control project in the border region. With investment of 5 million yuan ($785,000), the five-year project aims to prevent 90 percent of mother-infant HIV transmissions and ensure that more than 85 percent of carriers in the region will receive anti-viral treatment by 2018.

In 2000, about 10 percent of the population of Jiegao, which sits on the banks of a river that separates China and Myanmar, had HIV/AIDS, and tests conducted the following year showed that almost one in 10 long-distance truck drivers was infected, according to Wang Guolong, an officer at the prevention bureau's branch in Ruili. In the past five years, the HIV/AIDS rate among foreign truckers in Jiegao has fallen to 3 percent.

Concerns about the potential risks prompted the provincial bureau's center in Ruili to build a service center near the port in 2006. "The Drivers' Home" allows long-distance drivers to rest for a few days after their journey, and, more important, provides lectures and materials that help them learn more about the prevention and control of HIV/AIDS.

"The drivers' ages range from 18 to 60 years, but most of them are 30 to 40, a time when people are very active sexually," Wang says. Although there are no statistics to indicate the mortality rate among cross-border drivers, he says the truck companies occasionally alert the bureau to HIV/AIDS-related deaths among drivers. "Interventions should be introduced to save more people," he says.

The Drivers' Home, which covers an area of about 100 square meters and is next to the truck stop, provides free soft drinks and entertainment, such as TV, mahjong, poker and Myanmarese chess, to help the drivers resist the town's less healthy attractions.

The center provides free condoms and handbooks about HIV/AIDS, and employs two bilingual workers who give lectures on prevention and control. "It was difficult at the very beginning because the drivers were not familiar with the center and didn't know the purpose of our work," Wang says. In 2006, the center's first lecture had an audience of just 12, but last year more than 500 drivers attended 10 scheduled lectures.

Li Yingqing contributed to this story.

yangwanli@chinadaily.com.cn

(China Daily Africa Weekly 09/25/2015 page15)