[Analysis on gene sequence of HIV isolated from men who have sex with men in Beijing].

OBJECTIVE

To analyze genetic characteristics of HIV isolated from men who have sex with men (MSM) in Beijing and predict the epidemic trend in this population.

METHODS

All of the HIV gene sequences in our laboratory obtained from MSM in Beijing were used, which were aligned with all of the HIV gene sequences from MSM and other populations in China downloaded from Los Alamos HIV Database. Phylogenetic trees were constructed by using software PhyML 3.0, based on which the relationships of prevalent HIV strains between Beijing MSM and other populations in China were further explored. The evolution rate, the time of most recent common ancestor (tMRCA) , the epidemic parameters, the reproductive number (R0) were calculated by using software BEAST to predict HIV evolution and epidemic characteristics.

RESULTS

Multiple HIV subtypes, including subtype B, CRF01_AE and CRF07_BC, were found to be prevalent among MSM in Beijing. In ML tree constructed based on strains from the whole country, three clusters including B-1, CRF01_AE-1, and CRF01_AE-2 were found among the MSM in Beijing (accounting for 40%) . At least three independent introduction of B1 cluster strains into Beijing MSM were found, which were at March 1991 (July 1984-February 1997) , January 1994 (January 1989-January 1998) , April 1991 (August 1984-January 1996) . For CRF01_AE strains, two clusters including CRF01_AE-1 and CRF01_AE-2 were introduced into the population at December 2000 (March 1998-January 2003) and December 2001 (January 2000-July 2003) respectively. The population epidemiology of HIV in Beijing MSM was reconstructed based on sequences. The CRF01_AE-1 cluster spread more quickly than the other two clusters, and the evolution rate was higher.

CONCLUSION

Multiple HIV subtypes were found prevalent among MSM in Beijing. Although subtype B strain was introduced into Beijing MSM earlier than CRF01_AE strain, CRF01_AE strain increased more quickly than subtype B strain. More research and control of the CRF01_AE prevalence will be helpful for prevention and control of HIV epidemic in MSM in Beijing.