RV144 vaccine imprinting constrained HIV-1 evolution following breakthrough infection.

The scale of the HIV-1 epidemic underscores the need for a vaccine. The multitude of circulating HIV-1 strains together with HIV-1's high evolvability hints that HIV-1 could adapt to a future vaccine. Here, we wanted to investigate the effect of vaccination on the evolution of the virus post-breakthrough infection. We analyzed 2,635 HIV-1 env sequences sampled up to a year post-diagnosis from 110 vaccine and placebo participants who became infected in the RV144 vaccine efficacy trial. We showed that the Env signature sites that were previously identified to distinguish vaccine and placebo participants were maintained over time. In addition, fewer sites were under diversifying selection in the vaccine group than in the placebo group. These results indicate that HIV-1 would possibly adapt to a vaccine upon its roll-out.

Correction: RV144 HIV-1 vaccination impacts post-infection antibody responses.

[This corrects the article DOI: 10.1371/journal.ppat.1009101.].

Factors influencing estimates of HIV-1 infection timing using BEAST.

While large datasets of HIV-1 sequences are increasingly being generated, many studies rely on a single gene or fragment of the genome and few comparative studies across genes have been done. We performed genome-based and gene-specific Bayesian phylogenetic analyses to investigate how certain factors impact estimates of the infection dates in an acute HIV-1 infection cohort, RV217. In this cohort, HIV-1 diagnosis corresponded to the first RNA positive test and occurred a median of four days after the last negative test, allowing us to compare timing estimates using BEAST to a narrow window of infection. We analyzed HIV-1 sequences sampled one week, one month and six months after HIV-1 diagnosis in 39 individuals. We found that shared diversity and temporal signal was limited in acute infection, and insufficient to allow timing inferences in the shortest HIV-1 genes, thus dated phylogenies were primarily analyzed for env, gag, pol and near full-length genomes. There was no one best-fitting model across participants and genes, though relaxed molecular clocks (73% of best-fitting models) and the Bayesian skyline (49%) tended to be favored. For infections with single founders, the infection date was estimated to be around one week pre-diagnosis for env (IQR: 3-9 days) and gag (IQR: 5-9 days), whilst the genome placed it at a median of 10 days (IQR: 4-19). Multiply-founded infections proved problematic to date. Our ability to compare timing inferences to precise estimates of HIV-1 infection (within a week) highlights that molecular dating methods can be applied to within-host datasets from early infection. Nonetheless, our results also suggest caution when using uniform clock and population models or short genes with limited information content.

RV144 HIV-1 vaccination impacts post-infection antibody responses.

The RV144 vaccine efficacy clinical trial showed a reduction in HIV-1 infections by 31%. Vaccine efficacy was associated with stronger binding antibody responses to the HIV Envelope (Env) V1V2 region, with decreased efficacy as responses wane. High levels of Ab-dependent cellular cytotoxicity (ADCC) together with low plasma levels of Env-specific IgA also correlated with decreased infection risk. We investigated whether B cell priming from RV144 vaccination impacted functional antibody responses to HIV-1 following infection. Antibody responses were assessed in 37 vaccine and 63 placebo recipients at 6, 12, and 36 months following HIV diagnosis. The magnitude, specificity, dynamics, subclass recognition and distribution of the binding antibody response following infection were different in RV144 vaccine recipients compared to placebo recipients. Vaccine recipients demonstrated increased IgG1 binding specifically to V1V2, as well as increased IgG2 and IgG4 but decreased IgG3 to HIV-1 Env. No difference in IgA binding to HIV-1 Env was detected between the vaccine and placebo recipients following infection. RV144 vaccination limited the development of broadly neutralizing antibodies post-infection, but enhanced Fc-mediated effector functions indicating B cell priming by RV144 vaccination impacted downstream antibody function. However, these functional responses were not associated with clinical markers of disease progression. These data reveal that RV144 vaccination primed B cells towards specific binding and functional antibody responses following HIV-1 infection.

Novel monoclonal antibodies to the SERINC5 HIV-1 restriction factor detect endogenous andvirion-associated SERINC5.

SERINC5 is a multi-pass transmembrane protein that is thought to play a role in serine incorporation during cellular membrane biosynthesis. This protein has also been identified as a human immunodeficiency virus Type 1 (HIV-1) restriction factor. The paucity of monoclonal antibodies (mAbs) against SERINC5 has posed a challenge for the study of the endogenous protein. Here we report the development of novel anti-SERINC5 mAbs that target three distinct loops on the protein. We demonstrate that these SERINC5 mAbs can be used to detect endogenously expressed SERINC5 protein in various cell lines using Western blot, whole-cell ELISA, flow cytometry, and immunocytochemistry. We further show that some of these antibodies can detect SERINC5 that is present in HIV-1 viral stocks. These antibodies will aid in the characterization of the functions and mechanisms of action of SERINC5 in different cell types.

Neutralizing antibody VRC01 failed to select for HIV-1 mutations upon viral rebound.

Infusion of the broadly neutralizing antibody VRC01 has been evaluated in individuals chronically infected with HIV-1. Here, we studied how VRC01 infusions affected viral rebound after cessation of antiretroviral therapy (ART) in 18 acutely treated and durably suppressed individuals. Viral rebound occurred in all individuals, yet VRC01 infusions modestly delayed rebound and participants who showed a faster decay of VRC01 in serum rebounded more rapidly. Participants with strains most sensitive to VRC01 or with VRC01 epitope motifs similar to known VRC01-susceptible strains rebounded later. Upon rebound, HIV-1 sequences were indistinguishable from those sampled at diagnosis. Across the cohort, participant-derived Env showed different sensitivity to VRC01 neutralization (including 2 resistant viruses), yet neutralization sensitivity was similar at diagnosis and after rebound, indicating the lack of selection for VRC01 resistance during treatment interruption. Our results showed that viremia rebounded despite the absence of HIV-1 adaptation to VRC01 and an average VRC01 trough of 221 µg/mL. Although VRC01 levels were insufficient to prevent a resurgent infection, knowledge that they did not mediate Env mutations in acute-like viruses is relevant for antibody-based strategies in acute infection.

Molecular dating and viral load growth rates suggested that the eclipse phase lasted about a week in HIV-1 infected adults in East Africa and Thailand.

Most HIV-1 infected individuals do not know their infection dates. Precise infection timing is crucial information for studies that document transmission networks or drug levels at infection. To improve infection timing, we used the prospective RV217 cohort where the window when plasma viremia becomes detectable is narrow: the last negative visit occurred a median of four days before the first detectable HIV-1 viremia with an RNA test, referred below as diagnosis. We sequenced 1,280 HIV-1 genomes from 39 participants at a median of 4, 32 and 170 days post-diagnosis. HIV-1 infections were dated by using sequence-based methods and a viral load regression method. Bayesian coalescent and viral load regression estimated that infections occurred a median of 6 days prior to diagnosis (IQR: 9-3 and 11-4 days prior, respectively). Poisson-Fitter, which analyzes the distribution of hamming distances among sequences, estimated a median of 7 days prior to diagnosis (IQR: 15-4 days) based on sequences sampled 4 days post-diagnosis, but it did not yield plausible results using sequences sampled at 32 days. Fourteen participants reported a high-risk exposure event at a median of 8 days prior to diagnosis (IQR: 12 to 6 days prior). These different methods concurred that HIV-1 infection occurred about a week before detectable viremia, corresponding to 20 days (IQR: 34-15 days) before peak viral load. Together, our methods comparison helps define a framework for future dating studies in early HIV-1 infection.

Dynamics of Human Immunodeficiency Virus-1 Genetic Diversification During Acute Infection.

We analyzed human immunodeficiency virus envelope diversity in 98 acute infections. The within-host genetic diversity, divergence from transmitted/founder (T/F) strain, and the observed frequency of multiple T/F infections increased with Fiebig stage. These data identify rapid viral dynamics during acute infection with implications for clinical trials conducted in this setting.

A vaccine-induced gene expression signature correlates with protection against SIV and HIV in multiple trials.

Current HIV vaccines are only partially efficacious, presenting an opportunity to identify correlates of protection and, thereby, potential insight into mechanisms that prevent HIV acquisition. Two independent preclinical challenge studies in nonhuman primates (NHPs) previously showed partial efficacy of a mosaic adenovirus 26 (Ad26)-based HIV-1 vaccine candidate. To investigate the basis of this protection, we performed whole transcriptomics profiling by RNA sequencing (RNA-seq) in sorted lymphocytes from peripheral blood samples taken during these studies at different time points after vaccination but before challenge. We observed a transcriptional signature in B cells that associated with protection from acquisition of simian immunodeficiency virus (SIV) or the simian-human immunodeficiency virus (SHIV) in both studies. Strong antibody responses were elicited, and genes from the signature for which expression was enriched specifically associated with higher magnitude of functional antibody responses. The same gene expression signature also associated with protection in RV144 in the only human HIV vaccine trial to date that has shown efficacy and in two additional NHP studies that evaluated similar canarypox-based vaccine regimens. A composite gene expression score derived from the gene signature was one of the top-ranked correlates of protection in the NHP vaccine studies. This study aims to bridge preclinical and clinical data with the identification of a gene signature in B cells that is associated with protection from SIV and HIV infection by providing a new approach for evaluating future vaccine candidates.

Deep Sequencing Reveals Central Nervous System Compartmentalization in Multiple Transmitted/Founder Virus Acute HIV-1 Infection.

HIV-1 disseminates to a broad range of tissue compartments during acute HIV-1 infection (AHI). The central nervous system (CNS) can serve as an early and persistent site of viral replication, which poses a potential challenge for HIV-1 remission strategies that target the HIV reservoir. CNS compartmentalization is a key feature of HIV-1 neuropathogenesis. Thus far, the timing of how early CNS compartmentalization develops after infection is unknown. We examined whether HIV-1 transmitted/founder (T/F) viruses differ between CNS and blood during AHI using single-genome sequencing of envelope gene and further examined subregions in pol and env using next-generation sequencing in paired plasma and cerebrospinal fluid (CSF) from 18 individuals. Different proportions of mostly minor variants were found in six of the eight multiple T/F-infected individuals, indicating enrichment of some variants in CSF that may lead to significant compartmentalization in the later stages of infection. This study provides evidence for the first time that HIV-1 compartmentalization in the CNS can occur within days of HIV-1 exposure in multiple T/F infections. Further understanding of factors that determine enrichment of T/F variants in the CNS, as well as potential long-term implications of these findings for persistence of HIV-1 reservoirs and neurological impairment in HIV, is needed.

New Subtype B Containing HIV-1 Circulating Recombinant of sub-Saharan Africa Origin in Nigerian Men Who Have Sex With Men.

BACKGROUND: HIV-1 circulating recombinant forms (CRF) containing subtype B are uncommon in sub-Saharan Africa. Prevalent infections observed during enrollment of a prospective study of men who have sex with men (MSM) from Lagos, Nigeria, revealed the presence of a family of subtype B and CRF02_AG recombinants. This report describes the HIV-1 genetic diversity within a high-risk, high-prevalence, and previously undersampled cohort of Nigerian MSM. METHODS: Between 2013 and 2016, 672 MSM were enrolled at the Lagos site of the TRUST/RV368 study. Prevalent HIV-1 infections were initially characterized by pol sequencing and phylogenetic subtyping analysis. Samples demonstrating the presence of subtype B were further characterized by near full-length sequencing, phylogenetic, and Bayesian analyses. RESULTS: Within this cohort, HIV-1 prevalence was 59%. The major subtype was CRF02_AG (57%), followed by CRF02/B recombinants (15%), subtype G (13%), and smaller amounts of A1, B, and other recombinants. Nine clusters of closely related pol sequences indicate ongoing transmission events within this cohort. Among the CRF02_AG/B, a new CRF was identified and termed CRF95_02B. Shared risk factors and Bayesian phylogenetic inference of the new CRF95_02B and the similarly structured CRF56_cpx indicate a Nigerian or West African origin of CRF56_cpx before its observation in France. CONCLUSION: With high HIV-1 prevalence, new strains, and multiple transmission networks, this cohort of Nigerian MSM represents a previously hidden reservoir of HIV-1 strains, including the newly identified CRF95_02B and closely related CRF56_cpx. These strains will need to be considered during vaccine selection and development to optimize the design of a globally effective HIV-1 vaccine.

Atovaquone/proguanil therapy for Plasmodium falciparum and Plasmodium vivax malaria in Indonesians who lack clinical immunity.

Thirty-eight of 295 subjects participating in a randomized, double-blind, placebo-controlled trial of the efficacy of daily administration of atovaquone/proguanil for malaria prevention developed malaria at some time during the 20-week prophylaxis period. These subjects (3 atovaquone/proguanil recipients and 35 placebo recipients) were treated with 4 tablets of atovaquone/proguanil per day for 3 days. Atovaquone/proguanil provided safe, well-tolerated, and effective therapy for uncomplicated malaria in nonimmune Indonesians.

Randomized, placebo-controlled trial of atovaquone/proguanil for the prevention of Plasmodium falciparum or Plasmodium vivax malaria among migrants to Papua, Indonesia.

The increasing prevalence of resistance to antimalarial drugs reduces options for malaria prophylaxis. Atovaquone/proguanil (Malarone; GlaxoSmithKline) has been >95% effective in preventing Plasmodium falciparum malaria in lifelong residents of areas of holoendemicity, but data from persons without clinical immunity or who are at risk for Plasmodium vivax malaria have not been described. We conducted a randomized, double-blinded study involving 297 people from areas of nonendemicity in Indonesia who migrated to Papua (where malaria is endemic) < or =26 months before the study period. Subjects received prophylaxis with 1 Malarone tablet (250 mg of atovaquone and 100 mg of proguanil hydrochloride; n=148) or placebo (n=149) per day for 20 weeks. Hematologic and clinical chemistry values did not change significantly. The protective efficacy of atovaquone/proguanil was 84% (95% confidence interval [CI], 44%-95%) for P. vivax malaria, 96% (95% CI, 72%-99%) for P. falciparum malaria, and 93% (95% CI, 77%-98%) overall. Atovaquone/proguanil was well tolerated, safe, and effective for the prevention of drug-resistant P. vivax and P. falciparum malaria in individuals without prior malaria exposure who migrated to Papua, Indonesia.

Absence of antigenic competition in Aotus monkeys immunized with Plasmodium falciparum DNA vaccines delivered as a mixture.

Aotus lemurinus lemurinus monkeys were immunized four times with one of three DNA plasmids expressing important Plasmodium falciparum blood stage vaccine candidate proteins or with a mixture containing all three vaccines. The three vaccines encoded sequences from apical merozoite antigen-1 (AMA-1), erythrocyte binding protein-175 (EBA-175) and merozoite surface protein-1 (MSP-1). Antigen-specific enzyme-linked immunosorbant assays (ELISAs) showed no significant differences in antibody titer induced to the three antigens by a single vaccine compared with the titer induced to that same antigen by the trivalent preparation. Results of immunofluorescent antibody assays against erythrocytes infected with asexual blood stage P. falciparum indicated that each of the three monovalent vaccines induced significant antibody responses to whole parasites. The trivalent vaccine mixture induced, after four immunizations, an antibody titer to whole parasites that was 3--12-fold higher than those induced by any of the single vaccines. The fourth immunization with the trivalent vaccine increased the mean antibody in IFAT by more than five-fold.