Origin and dynamics of HIV-1 subtype C infection in India.
OBJECTIVE
To investigate the geographical origin and evolution dynamics of HIV-1 subtype C infection in India.


METHODS
Ninety HIV-1 subtype C env gp120 subtype C sequences from India were compared with 312 env gp120 reference subtype C sequences from 27 different countries obtained from Los Alamos HIV database. All the HIV-1 subtype C env gp120 sequences from India were used for the geographical origin analysis and 61 subtype C env gp120 sequences with known sampling year (from 1991 to 2008) were employed to determine the origin of HIV infection in India.


METHODS
Phylogenetic analysis of HIV-1 env sequences was used to investigate the geographical origin and tMRCA of Indian HIV-1 subtype C. Evolutionary parameters including origin date and demographic growth patterns of Indian subtype C were estimated using a Bayesian coalescent-based approach under relaxed molecular clock models.


RESULTS
The majority of the analyzed Indian and South African HIV-1 subtype C sequences formed a single monophyletic cluster. The most recent common ancestor date was calculated to be 1975.56 (95% HPD, 1968.78-1981.52). Reconstruction of the effective population size revealed three phases of epidemic growth: an initial slow growth, followed by exponential growth, and then a plateau phase approaching present time. Stabilization of the epidemic growth phase correlated with the foundation of National AIDS Control Organization in India.


CONCLUSIONS
Indian subtype C originated from a single South African lineage in the middle of 1970s. The current study emphasizes not only the utility of HIV-1 sequence data for epidemiological studies but more notably highlights the effectiveness of community or government intervention strategies in controlling the trend of the epidemic.
Department of Infectious Diseases and Microbiology Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
Chengli
C
Shen
Jodi
J
Craigo
Ming
M
Ding
Yue
Y
Chen
Phalguni
P
Gupta
D001499:Bayes Theorem; D019143:Evolution, Molecular; D005843:Geography; D015699:HIV Envelope Protein gp120 / Q000235:genetics; D015658:HIV Infections / Q000453:epidemiology* / Q000821:virology*; D015497:HIV-1 / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity*; D006801:Humans; D007194:India / Q000453:epidemiology; D010802:Phylogeny
D015699:HIV Envelope Protein gp120; C514793:gp120 protein, Human immunodeficiency virus 1