Transmission origin of HIV-1 CRF01_AE and B subtype among injecting drug user in Taiwan

Introduction and Objectives: The major genotypes of HIV-1 were CRF07_BC, subtype B and CRF01_AE in Taiwan since 2005. In the previous study, we already present the evolution pattern of CRF07_BC among injecting drug users(IDUs). This study further supported the evidence of HIV-1 CRF01_AE and subtype B transmission origin among same population. Methods: This study collected HIV-1 seropositive blood samples (N=310) from hospital in Taiwan since 2007. We use phylogenetic analysis to detect HIV-1 virus strains of the subtypes in env gene. The coalescent theory and molecular clock analysis were used to estimate the evolution rate and time for “The Most Recent Common Ancestors (TMRCA) among IDUs. Results: There was one clustering phylogenetic branch including 9 CRF01_AE sequences presented as an outbreak among IDUs. 89% of these 9 patients were male and the average age was 35.7. The evolution rate of CRF01_AE is 8.2×10-3 (4.9×10-3-11.6×10-3, 95% Highest Posterior Density(HPD)) and subtype B is 6.2×10-3 (4.2×10-3-8.2×10-3, 95% HPD). The TMRCA of CRF01_AE in Taiwan were dated to 1984.6 (1978.2-1989, 95% HPD) and subtype B in central Taiwan(cluster 1) were dated to 1991.9(1985.8-1997.4, 95% HPD), and the skyline plot showed the CRF01_AE origin from 1985 and subtype B origin from 1980 in Taiwan. Conclusion: The estimate in this study shown the evolution rate of CRF01_AE was higher than subtype B among Taiwan injecting drug users. Furthermore, the transmission origin of these two genotype among whole IDUs were trace back early than 1984.