AIDS RESEARCH AND HUMAN RETROVIRUSES Volume 20, Number 3, 2004, pp. 341–345 © Mary Ann Liebert, Inc. Sequence Note HIV-1 CRF01_ AE in Intravenous Drug Users in Hanoi, Vietnam TRAN THI THANH HA, 1 IRINA MALJKOVIC, 2,3 SOFIE SWARTLING, 2 PHUNG DAC CAM, 1 FRANCESCA CHIODI, 3 and THOMAS LEITNER 2,4 ABSTRACT To investigate the molecular epidemiology of HIV-1 among intravenous drug users (IDUs) in Hanoi we col- lected 17 samples from individuals living in 12 locations in and around Hanoi. The HIV-1 env V3 and gag p17 regions were directly sequenced from the proviral PBMC population. The majority of the IDUs were in- fected with HIV-1 CRF01_ AE and one individual carried a p17/V3 CRF01/subtype C recombinant. The CRF01 viruses found among these individuals did not seem to be directly epidemiologically linked to each other. The sequences were, however, related to previously reported CRF01 sequences from Vietnam and China. Thus, IDUs in Hanoi seem to have derived their infections in Vietnam, but not from the same source. The discov- ery of the CRF01/C recombinant shows that new viral forms easily can be generated in IDU transmission chains. 341 H IV-1 IS RAPIDLY SPREADING IN MANY ASIAN COUNTRIES. 1 In Vietnam, the first case of HIV was detected in 1990 in Ho Chi Minh City. At the end of 1998,the HIV epidemic had spread to all 61 cities and districts of Vietnam. Furthermore, HIV-in- fected subjects have not only been found in densely populated cities and districts but also in the countryside and among eth- nic minorities in the mountains. According to the Center for Preventive Medicine of Hanoi City there are, at present (April 2003),about 62,000 HIV-infectedpersonsreportedin the whole country, of which 64% are intravenous drug users and 86% are male. The estimated numbers of infected, however, were 91,000–115,000in 1999 and 118,000–150,0000in 2000. At this rate, the number of infections may rise to 197,700–251,600 by the end of 2005. Partly explained by the relatively recent in- troduction of HIV into Vietnam, but of some concern, is that the progression from HIV positive to AIDS is now only 3–5 years in Vietnam, considerably faster than in other countries. In 2000, 4785 cases of AIDS were reported, of which 2525 had died of AIDS. In Hanoi, the number of HIV and AIDS cases has increased rapidly since 1997 with .2100 cumulative cases reported until March 2001, representingthe fourth highest num- ber of HIV cases in Vietnam by city, after Ho Chi Minh City, Quang Ninh, and Hai Phong. Previous studies have shown that the Asian epidemic mainly involves subtypes B, C, and CRF01_ AE in Thailand, India, Myanmar, and Bangladesh. 2–8 In addition, subtype A and sev- eral novel recombinant forms have been reported. 9 In recent outbreaks among primarily intravenous drug users (IDUs) in China different subtypes have been linked to drug trafficking routes, including subtypes B, C, and CRF01_ AE and a B/C re- combinantvirus. 10,11 Worldwide,subtypeC is currentlyspread- ing more than any other subtype. 9 In Vietnam, previous stud- ies in the south in Ho Chi Minh City have shown that CRF01_ AE predominates among IDUs and commercial sex workers. 12,13 Similarities between HIV-1 strains in the Guangxi Province of southern China and drug users in northern Vietnam 1 National Institute of Hygiene and Epidemiology, Hanoi, Vietnam. 2 Swedish Institute for Infectious Disease Control, 17182 Solna, Sweden. 3 Microbiology and Tumorbiology Center, Karolinska Institute, 17177 Stockholm, Sweden. 4 Theoretical Biology and Biophysics, Group T-10, MS K710, Los Alamos National Laboratory, Los Alamos, New Mexico 87545.