Chronology of the HIV-1 CRF07_BC expansion in East Asia

Abstract

The HIV-1 epidemic among injecting drug users (IDU) in Taiwan is caused primarily by CRF07_BC infections. Evolutionary analyses, which utilize outgroup reference strains from northwestern China (Xinjiang), reveal that CRF07_BC was introduced into southern Taiwan in 1998-2001 and spread to central-northern Taiwan in 2001-2003, causing the largest HIV/AIDS epidemic in Taiwan. The separate introduction of CRF07_BC into Xinjiang occurred in 1992-1995. This study illustrates the temporal dynamics of CRF07_BC spread among IDU across east Asia.

Temporal and Spatial Dynamics of Human Immunodeficiency Virus Type 1 Circulating Recombinant Forms 08_BC and 07_BC in Asia

“…This is in agreement with previous studies, based on the env gene, which dated the divergence time of CRF07_BC to about 1993 (43). The exponential and logistic demographic model gave slightly lower substitution rates and hence older MRCA estimates.…”

“…CRF08_BC and CRF07_BC are two subtype C-related recombinants with significant epidemic impact in China and beyond (42,43). Prior to the emergence of CRF08_BC and CRF07_BC (26,38), subtype C isolates closely related to Indian strains predominated, especially in the southern part of China (19).…”

“…c Constant size and exponential growth analyses based on the hypervariable region-stripped env gene previously described (43).…”

“…However, we note that the estimated coalescence times, particularly for clusters with a small number of sequences, may be biased and hence more recent than the date of outbreak. This is because, among other factors, the extant virus diversity has been partially sampled; alternatively, the founding/parental lineages of the outbreak have since become extinct or are yet to be discovered (1,43). Conversely, all gag sequences of CRF07_BC from Yunnan, Xinjiang, and Liaoning formed a single cluster, with subtype C isolates of Indian origin paraphyletic with respect to CRF07_ BC (Fig.…”

“…Although molecular epidemiologic surveys have previously reported the identification and characterization in various parts of China of CRF08_BC, CRF07_BC and their putative subtype C parental lineages (19,26,32,38), the specific times of emergence and divergence of these strains in the world's most populous nation remain uninvestigated and unknown. Genealogical analysis is needed to reconstruct the epidemiological history of viral populations (8,9,43), which can lead to better understanding of HIV transmission and improved prevention programs.…”