Molecular epidemiology of HIV-1 in central Taiwan during 2007-2008

OBJECTIVES: The human immunodeficiency virus type 1 (HIV-1) epidemic in Taiwan is rapidly escalating because of an increasing number of injection drug users (IDUs) since 2003. CRF07_BC is one major recombinants descended from subtypes B and C'. Despite this massive epidemic impact in Taiwan, it's migration patterns and divergence times remain unknown. This study intended to understand the epidemiology situation of HIV-1 subtypes in 2007-2008 at central Taiwan, and tracing the original infection.

Methods: The 68 HIV-1-positive specimens were collected from 2007-2008 outpatient services and prison in central Taiwan, all contained detectable sequences from region of env gene. This study conducted a phylogenetic tree analysis and population genetic analyses by adding 2002-2007 CRF07_BC specimens under the HKY-constant size、HKY-logistic size、HKY-exponential size、GTR-constant size、GTR-logistic size、GTR-exponential size model based on Bayesian Markov chain Monte Carlo framework.

Results: The results shown 58.8% of 68 specimens was CRF07_BC subtype; 8.8% was CRF01_AE subtype; 25% was B subtype. CRF07_BC was found to be the most predominant clade of HIV-1 in central Taiwan during 2007-2008. Furthermore, the skyline of CRF07_BC molecular clock analysis shown the evolution rate of CRF07_BC in central Taiwan was 4.201×10-3 and the originator of outbreak was about 1999.

Conclusions: Our results illustrate the history of the HIV-1 CRF07_BC spread pathway and evolution , and it provide an important reference for HIV scientists, public health officials and HIV vaccine designers.