Epidemiological study of phylogenetic transmission clusters in a local HIV-1 epidemic reveals distinct differences between subtype B and non-B infections

The number of HIV-1 infected individuals in the Western world continues to rise. More in-depth understanding of regional HIV-1 epidemics is necessary for the optimal design and adequate use of future prevention strategies.

The use of a combination of phylogenetic analysis of HIV sequences, with data on patients'demographics, infection route, clinical information and laboratory results, will allow a better characterization of individuals responsible for local transmission.

Methods: Baseline HIV-1 pol sequences, obtained through routine drug-resistance testing, from 506 patients, newly diagnosed between 2001 and 2009, were used to construct phylogenetic trees and identify transmission-clusters. Patients'demographics, laboratory and clinical data, were retrieved anonymously.

Statistical analysis was performed to identify subtype-specific and transmission-cluster-specific characteristics.

Results: Multivariate analysis showed significant differences between the 59.7% of individuals with subtype B infection and the 40.3% non-B infected individuals, with regard to route of transmission, origin, infection with Chlamydia (p=0.01) and infection with Hepatitis C virus (p=0.017). More and larger transmission-clusters were identified among the subtype B infections (p<0.001).

Overall, in multivariate analysis, clustering was significantly associated with Caucasian origin, infection through homosexual contact and younger age (all p<0.001). Bivariate analysis additionally showed a correlation between clustering and syphilis (p<0.001),higher CD4 counts (p=0.002), Chlamydia infection (p=0.013) and primary HIV (p=0.017).

Conclusions: Combination of phylogenetics with demographic information, laboratory and clinical data, revealed that HIV-1 subtype B infected Caucasian men-who-have-sex-with-men with high prevalence of sexually transmitted diseases, account for the majority of local HIV-transmissions.

This finding elucidates observed epidemiological trends through molecular analysis, and justifies sustained focus in prevention on this high risk group.

Author: Kristen ChalmetDelfien StaelensStijn BlotSylvie DinakisJolanda PelgromJean PlumDirk VogelaersLinos VandekerckhoveChris Verhofstede

Credits/Source: BMC Infectious Diseases 2010, 10:262

Published on: 2010-09-07
 
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