Background: Over the past years, an increasing trend was noticed for non-B and non-
CRF01_AE HIV-1 strains prevalence in Hong Kong.
Objective: In this study, we aimed at using the available HIV-1 pol sequences collected from 1994
to 2013 through our local antiretroviral resistance surveillance program to investigate the molecular
epidemiology and evolution of HIV-1 minority subtypes in Hong Kong. We also aimed at investigating
their potential association and impact of those transmission risk groups.
Methods: A total of 2,315 HIV-1 partial pol sequences were included. HIV-1 genotypes were determined
by REGA Genotyping Tool and phylogenetic analysis with reference sequences. The viral
evolutionary rates and time of the most common ancestor (tMRCA) were estimated by Bayesian
Markov Chain Monte Carlo (MCMC) interference.
Results: Apart from the two prevalent HIV-1 genotypes in Hong Kong (subtype B,41.6%,
CRF01_AE,40.5%), phylogenetic analysis revealed a broad viral diversity including
CRF07_BC(5.1%), subtype C(4.5%), CRF02_AG(1.1%), CRF08_BC(0.8%), subtype A1(0.8%),
subtype G(0.4%), subtype D(0.4%), CRF06_cpx(0.4%), subtype F(0.1%), CRF12_BF(0·04%) and
other recombinants(4.5%). The top five minority subtypes were further analyzed which demonstrated
distinct epidemiological and phylogenetic patterns. Over 70% of subtypes A1, C and
CRF02_AG infections were circulated among non-Chinese Asians or African community in Hong
Kong and were mainly transmitted between heterosexual regular partners. Instead, over 90% of
CRF07_BC and CRF08_BC patients were Chinese. An epidemic cluster was identified in
CRF07_BC and estimated to expand from 2002 onwards based on skyline plot and molecular clock
Conclusion: Our results highlighted the emergence of CRF07_BC epidemic in local MSM community,
public health interventions targeting the community should be further enhanced to tackle the