Abstract
ObjectiveCharacterization of HIV-1 sequences in newly infected individuals is important for elucidating the mechanisms of viral sexual transmission. We report the identification of transmitted/founder viruses in eight pairs of HIV-1 sexually-infected patients enrolled at the time of primary infection (“recipients”) and their transmitting partners (“donors”).MethodsUsing a single genome-amplification approach, we compared quasispecies in donors and recipients on the basis of 316 and 376 C2V5 env sequences amplified from plasma viral RNA and PBMC-associated DNA, respectively.ResultsBoth DNA and RNA sequences indicated very homogeneous viral populations in all recipients, suggesting transmission of a single variant, even in cases of recent sexually transmitted infections (STIs) in donors (n = 2) or recipients (n = 3). In all pairs, the transmitted/founder virus was derived from an infrequent variant population within the blood of the donor. The donor variant sequences most closely related to the recipient sequences were found in plasma samples in 3/8 cases and/or in PBMC samples in 6/8 cases. Although donors were exclusively (n = 4) or predominantly (n = 4) infected by CCR5-tropic (R5) strains, two recipients were infected with highly homogeneous CXCR4/dual-mixed-tropic (X4/DM) viral populations, identified in both DNA and RNA. The proportion of X4/DM quasispecies in donors was higher in cases of X4/DM than R5 HIV transmission (16.7–22.0% versus 0–2.6%), suggesting that X4/DM transmission may be associated with a threshold population of X4/DM circulating quasispecies in donors.ConclusionsThese suggest that a severe genetic bottleneck occurs during subtype B HIV-1 heterosexual and homosexual transmission. Sexually-transmitted/founder virus cannot be directly predicted by analysis of the donor’s quasispecies in plasma and/or PBMC. Additional studies are required to fully understand the traits that confer the capacity to transmit and establish infection, and determine the role of concomitant STIs in mitigating the genetic bottleneck in mucosal HIV transmission.
Highlights
The transmission of human immunodeficiency virus type 1 (HIV-1) and the establishment of a productive infection are complex biological processes, and the details of the mechanisms remain to be elucidated
In 2008, Keele et al devised a novel strategy for a more precise molecular identification and enumeration of transmitted HIV-1 genomes [13]. This method, Single Genome Amplification (SGA)-direct amplicon sequencing, was recently applied to clinical cohorts of acutely infected individuals [13,14,15,16,17], and the findings indicated that approximately 80% of heterosexual subjects and 60% of men who have sex with men (MSM) are productively infected by a single viral genome
We report a study of eight transmission pairs, each of them including a sexually-infected patient enrolled into the French ANRS PRIMO cohort at the time of primary HIV-1 infection (PHI) (‘‘recipient’’) and his/her HIV-1-infected sexually-transmitting partner (‘‘donor’’)
Summary
The transmission of human immunodeficiency virus type 1 (HIV-1) and the establishment of a productive infection are complex biological processes, and the details of the mechanisms remain to be elucidated. In 2008, Keele et al devised a novel strategy for a more precise molecular identification and enumeration of transmitted HIV-1 genomes [13] This method, SGA-direct amplicon sequencing, was recently applied to clinical cohorts of acutely infected individuals [13,14,15,16,17], and the findings indicated that approximately 80% of heterosexual subjects and 60% of MSM are productively infected by a single viral genome. Since most of these studies only characterized the transmitted viral population in recipients, little information was available about its relationship with virus circulating in the donor. Few of these studies compared the viral populations identified by analysis of both RNA and DNA samples from donor/recipient pairs
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