High rates of forward transmission events after acute/early HIV-1 infection.
BACKGROUND
A population-based phylogenetic approach was used to characterize human immunodeficiency virus (HIV)-transmission dynamics in Quebec.


METHODS
HIV-1 pol sequences included primary HIV infections (PHIs; <6 months after seroconversion) from the Quebec PHI cohort (1998-2005; n=215) and the provincial genotyping program (2001-2005; n=481). Phylogenetic analysis determined sequence interrelationships among unique PHIs (n=593) and infections from untreated (n=135) and treated (n=660) chronically infected (CI) potential transmitter populations (2001-2005). Clinical features, risk factors, and drug resistance for clustered and nonclustered transmission events were ascertained.


RESULTS
Viruses from 49.4% (293/593) of PHIs cosegregated into 75 transmission chains with 2-17 transmissions/cluster. Half of the clusters included 2.7+/-0.8 (mean+/-SD) transmissions, whereas the remainder had 8.8+/-3.5 transmissions. Maximum periods for onward transmission in clusters were 15.2+/-9.5 months. Coclustering of untreated and treated CIs with PHIs were infrequent (6.2% and 4.8%, respectively). The ages, viremia, and risk factors were similar for clustered and nonclustered transmission events. Low prevalence of drug resistance in PHI supported amplified transmissions at early stages.


CONCLUSIONS
Early infection accounts for approximately half of onward transmissions in this urban North American study. Therapy at early stages of disease may prevent onward HIV transmission.
Brenner
Bluma G
BG
McGill AIDS Centre-Jewish General Hospital, Montreal, Canada.
Roger
Michel
M
Routy
Jean-Pierre
JP
Moisi
Daniela
D
Ntemgwa
Michel
M
Matte
Claudine
C
Baril
Jean-Guy
JG
Thomas
Rejéan
R
Rouleau
Danielle
D
Bruneau
Julie
J
Leblanc
Roger
R
Legault
Mario
M
Tremblay
Cecile
C
Charest
Hugues
H
Wainberg
Mark A
MA
D000328:Adult; D019380:Anti-HIV Agents / Q000627:therapeutic use; D004279:DNA, Viral / Q000032:analysis; D018562:Disease Transmission, Infectious; D024882:Drug Resistance, Viral / Q000235:genetics*; D005260:Female; D015751:Genes, pol; D014644:Genetic Variation; D015658:HIV Infections / Q000188:drug therapy / Q000453:epidemiology* / Q000209:etiology / Q000635:transmission* / Q000821:virology; D015497:HIV-1 / Q000145:classification / Q000235:genetics*; D006801:Humans; D008297:Male; D010802:Phylogeny; D011792:Quebec / Q000453:epidemiology; D012307:Risk Factors
D019380:Anti-HIV Agents; D004279:DNA, Viral