Molecular epidemiological study of HIV-1 CRF01-ae transmission in Hong Kong

OBJECTIVES:: The objective of this study was to investigate the transmission history of the HIV-1 CRF01-AE epidemics in Hong Kong between 1994 and 2007. METHODS:: A total of 465 HIV-1 CRF01-AE pol sequences were derived from an in-house or a commercial HIV-1 genotyping system. Phylogenies of CRF01-AE sequences were analyzed by the Bayesian coalescent method. RESULTS:: CRF01-AE patient population included 363 males (78.1%) and 102 females (21.9%), whereas 65% (314 of 465) were local Chinese. Major transmission routes were heterosexual contact (63%), followed by intravenous drug use (IDU) (19%) and men having sex with men (MSM) (17%). From phylogenetic analysis, local CRF01-AE strains were from multiple origins with 3 separate transmission clusters identified. Cluster 1 consisted mainly of Chinese male IDUs and heterosexuals. Clusters 2 and 3 included mainly local Chinese MSM and non-Chinese Asian IDUs, respectively. Chinese reference isolates available from China (Fujian, Guangxi, or Liaoning) were clonally related to our transmission clusters, demonstrating the epidemiological linkage of CRF01-AE infections between Hong Kong and China. The 3 individual local transmission clusters were estimated to have initiated since late 1980s and late 1990s, causing subsequent epidemics in the early 2000s. CONCLUSIONS:: This is the first comprehensive molecular epidemiological study of HIV-1 CRF01-AE in Hong Kong. It revealed that MSM contact is becoming a major route of local CRF01-AE transmission in Hong Kong. Epidemiological linkage of CRF01-AE between Hong Kong and China observed in this study indicates the importance of regular molecular epidemiological surveillance for the HIV-1 epidemic in our region.