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BackgroundTransmitted/founder viruses isolated at the early stage of infection are indicators of the variants that are spreading within a population. The French reporting system for new HIV diagnoses is linked to a virological surveillance using dried serum spots.MethodsWe combined an immunoassay for very recent infection (less than 31 days) to a phylogenetic analysis of transmitted/founder viruses and sociodemographic information to analyze the dynamics of the HIV-1 epidemic during a 3-year period. Bayesian coalescent-based methods were used to explore the temporal and spatial dynamics of the identified clusters.ResultsOf 17 010 dried serum spots collected, 549 very recent infections were identified for which both env sequences and sociodemographic data were available. Non-B transmitted/founder viruses were found in 196 cases (35.7%), belonging to six subtypes and seven circulating recombinant forms. Forty-three dyads/clusters were identified (range 2-11 cases), including 107 individuals (19.5%), mainly MSM. The largest cluster involved MSM infected by a CRF02_AG variant. Reconstruction of viral migrations across time suggests that Paris was the major hub of dissemination.ConclusionThe study shows the feasibility of the surveillance of the HIV epidemic using this methodology. The observation of actively growing spatiotemporal clusters allows identification of specific networks that may be targets for intervention.

Compartmentalization of HIV-1 has been observed in the cerebrospinal fluid (CSF) of patients at different clinical stages. Considering the low permeability of the blood-brain barrier, we wondered if a reduced selective pressure by neutralizing antibodies (NAb) in the central nervous system (CNS) could favor the evolution of NAb-sensitive viruses in this compartment. Single genome amplification (SGA) was used to sequence full-length HIV-1 envelope variants (453 sequences) from paired CSF and blood plasma samples in 9 subjects infected by HIV variants of various clades and suffering from diverse neurologic disorders. Dynamics of viral evolution were evaluated with a bayesian coalescent approach for individuals with longitudinal samples. Pseudotyped viruses expressing envelope glycoproteins variants representative of the quasi-species present in each compartment were generated, and their sensitivity to autologous neutralization, broadly neutralizing antibodies (bNAbs) and entry inhibitors was assessed. Significant compartmentalization of HIV populations between blood and CSF were detected in 5 out of 9 subjects. Some of the previously described genetic determinants for compartmentalization in the CNS were observed regardless of the HIV-1 clade. There was no difference of sensitivity to autologous neutralization between blood- and CSF-variants, even for subjects with compartmentalization, suggesting that selective pressure by autologous NAb is not the main driver of HIV evolution in the CNS. However, we observed major differences of sensitivity to sCD4 or to at least one bNAb targeting either the N160-V1V2 site, the N332-V3 site or the CD4bs, between blood- and CSF-variants in all cases. In particular, HIV-1 variants present in the CSF were more resistant to bNAbs than their blood counterpart in some cases. Considering the possible migration from CSF to blood, the CNS could be a reservoir of bNAb resistant viruses, an observation that should be considered for immunotherapeutic approaches.

A family of dithienosilole-based dyes with alternating donor and acceptor conjugated groups, decorated with linear or branched alkyl chains at different positions on the backbone, have been obtained and investigated in different aggregation states. These dyes are characterized by almost panchromatic absorption and by near-IR emission, with good quantum yields in a variety of solvents with different polarity. We demonstrate that the nature and position of the alkyl substituents strongly govern the self-assembly of the dyes, whose packing is also sensitive to external stimuli, such as grinding and water addition. Thanks to computational results and theoretical modelling, we are able to interpret the results based on two possible preferential packings, characterized by distinct spectroscopic behaviour, whose abundance can be tuned according to the nature and position of the alkyl chains, as well as via external stimuli. [ABSTRACT FROM AUTHOR]

BackgroundMother-to-child transmission (MTCT) is responsible for most pediatric HIV-1 infections worldwide. It can occur during pregnancy, labor, or breastfeeding. Numerous studies have used coalescent and molecular clock methods to understand the epidemic history of HIV-1, but the timing of vertical transmission has not been studied using these methods. Taking advantage of the constant accumulation of HIV genetic variation over time and using longitudinally sampled viral sequences, we used a coalescent approach to investigate the timing of MTCT.Materials and methodsSix-hundred and twenty-two clonal env sequences from the RNA and DNA viral population were longitudinally sampled from nine HIV-1 infected mother-and-child pairs [range: 277-1034 days]. For each transmission pair, timing of MTCT was determined using a coalescent-based model within a Bayesian statistical framework. Results were compared with available estimates of MTCT timing obtained with the classic biomedical approach based on serial HIV DNA detection by PCR assays.ResultsFour children were infected during pregnancy, whereas the remaining five children were infected at time of delivery. For eight out of nine pairs, results were consistent with the transmission periods assessed by standard PCR-based assay. The discordance in the remaining case was likely confused by co-infection, with simultaneous introduction of multiple maternal viral variants at the time of delivery.ConclusionsThe study provided the opportunity to validate the Bayesian coalescent approach that determines the timing of MTCT of HIV-1. It illustrates the power of population genetics approaches to reliably estimate the timing of transmission events and deepens our knowledge about the dynamics of viral evolution in HIV-infected children, accounting for the complexity of multiple transmission events.

BackgroundThe evolution of HIV-1 and its immune escape to autologous neutralizing antibodies (Nabs) during the acute/early phases of infection have been analyzed in depth in many studies. In contrast, little is known about neither the long-term evolution of the virus in patients who developed broadly Nabs (bNabs) or the mechanism of escape in presence of these bNabs.ResultsWe have studied the viral population infecting a long term non progressor HIV-1 infected patient who had developed broadly neutralizing antibodies toward all tier 2/3 viruses (6 clades) tested, 9 years after infection, and was then followed up over 7 years. The autologous neutralization titers of the sequential sera toward env variants representative of the viral population significantly increased during the follow-up period. The most resistant pseudotyped virus was identified at the last visit suggesting that it represented a late emerging escape variant. We identified 5 amino acids substitutions that appeared associated with escape to broadly neutralizing antibodies. They were V319I/S, R/K355T, R/W429G, Q460E and G/T463E, in V3, C3 and V5 regions.ConclusionThis study showed that HIV-1 may continue to evolve in presence of both broadly neutralizing antibodies and increasing autologous neutralizing activity more than 10 years post-infection.