Scientific Publications

Recent efforts toward HIV vaccine development include the design of immunogens that can engage B cell receptors with the potential to affinity mature into broadly neutralizing antibodies (bnAbs). V2-apex bnAbs, which bind a protein-glycan region on HIV envelope glycoprotein (Env) trimer, are among the most broad and potent described. We show here that a rare 'glycan hole' at the V2 apex is enriched in HIV isolates neutralized by inferred precursors of prototype V2-apex bnAbs. To investigate whether this feature could focus neutralizing responses onto the apex bnAb region, we immunized wild-type rabbits with soluble trimers adapted from these Envs. Potent autologous tier 2 neutralizing responses targeting basic residues in strand C of the V2 region, which forms the core epitope for V2-apex bnAbs, were observed. Neutralizing monoclonal antibodies (mAbs) derived from these animals display features promising for subsequent broadening of the response.

HIV-1 sequence diversity presents a major challenge for the clinical development of broadly neutralizing antibodies (bNAbs) for both therapy and prevention. Sequence variation in critical bNAb epitopes has been observed in most HIV-1-infected individuals and can lead to viral escape after bNAb monotherapy in humans. We show that viral sequence diversity can limit both the therapeutic and prophylactic efficacy of bNAbs in rhesus monkeys. We first demonstrate that monotherapy with the V3 glycan-dependent antibody 10-1074, but not PGT121, results in rapid selection of preexisting viral variants containing N332/S334 escape mutations and loss of therapeutic efficacy in simian-HIV (SHIV)-SF162P3-infected rhesus monkeys. We then show that the V3 glycan-dependent antibody PGT121 alone and the V2 glycan-dependent antibody PGDM1400 alone both fail to protect against a mixed challenge with SHIV-SF162P3 and SHIV-325c. In contrast, the combination of both bNAbs provides 100% protection against this mixed SHIV challenge. These data reveal that single bNAbs efficiently select resistant viruses from a diverse challenge swarm to establish infection, demonstrating the importance of bNAb cocktails for HIV-1 prevention.

The World Health Organization recommends that countries conduct two phase evaluations of HIV rapid tests (RTs) in order to come up with the best algorithms. In this report, we present the first ever such evaluation in Uganda, involving both blood and oral based RTs. The role of weak positive (WP) bands on the accuracy of the individual RT and on the algorithms was also investigated.

The production of native-like recombinant versions of the HIV-1 envelope glycoprotein (Env) trimer requires overcoming the natural flexibility and instability of the complex. The engineered BG505 SOSIP.664 trimer mimics the structure and antigenicity of native Env. Here, we describe how the introduction of new disulfide bonds between the glycoprotein (gp)120 and gp41 subunits of SOSIP trimers of the BG505 and other genotypes improves their stability and antigenicity, reduces their conformational flexibility, and helps maintain them in the unliganded conformation. The resulting next-generation SOSIP.v5 trimers induce strong autologous tier-2 neutralizing antibody (NAb) responses in rabbits. In addition, the BG505 SOSIP.v6 trimers induced weak heterologous NAb responses against a subset of tier-2 viruses that were not elicited by the prototype BG505 SOSIP.664. These stabilization methods can be applied to trimers from multiple genotypes as components of multivalent vaccines aimed at inducing broadly NAbs (bNAbs).

HIV-1 envelope glycoprotein (Env) is the sole target for broadly neutralizing antibodies (bnAbs) and the focus for design of an antibody-based HIV vaccine. The Env trimer is covered by ∼90N-linked glycans, which shield the underlying protein from immune surveillance. bNAbs to HIV develop during infection, with many showing dependence on glycans for binding to Env. The ability to routinely assess the glycan type at each glycosylation site may facilitate design of improved vaccine candidates. Here we present a general mass spectrometry-based proteomics strategy that uses specific endoglycosidases to introduce mass signatures that distinguish peptide glycosites that are unoccupied or occupied by high-mannose/hybrid or complex-type glycans. The method yields >95% sequence coverage for Env, provides semi-quantitative analysis of the glycosylation status at each glycosite. We find that most glycosites in recombinant Env trimers are fully occupied by glycans, varying in the proportion of high-mannose/hybrid and complex-type glycans.

Home-based HIV counselling & testing (HBHCT) is highly acceptable and has the potential to increase HIV testing uptake in sub-Saharan Africa. However, data are lacking on strategies that can effectively link HIV-positive individuals identified through HBHCT to care. This trial was designed to assess the effectiveness of two brief home-based counselling sessions on linkage to care, provided subsequent to referral for care among HIV-positive patients identified through HBHCT in a rural community in Masaka district, Uganda.

Hepatitis C virus (HCV) incidence among HIV-positive men who have sex with men (MSM) has increased since 2000, although there are regional differences. We aimed to 1) estimate trends in HCV incidence among HIV-positive MSM, 2) assess the association between incidence and geographical region, age and HIV-related measurements and, 3) assess temporal changes from HIV seroconversion to HCV infection.

It has been suggested that Schistosoma mansoni, which is endemic in African fishing communities, might increase susceptibility to human immunodeficiency virus (HIV) acquisition. If confirmed, this would be of great public health importance in these high HIV-risk communities. This study was undertaken to determine whether S. mansoni infection is a risk factor for HIV infection among the fishing communities of Lake Victoria, Uganda. We conducted a matched case-control study, nested within a prospective HIV incidence cohort, including 50 HIV seroconverters (cases) and 150 controls during 2009-2011.

HIV incidence among young women in sub-Saharan Africa remains high and their inclusion in vaccine and cure efforts is crucial. We aimed to establish a cohort of young women detected during Fiebig stage I acute HIV infection in whom treatment was initiated immediately after diagnosis to advance research in this high-risk group.

INTRODUCTION: HIV incidence is the rate of new infections in a population over time. HIV incidence is a critical indicator needed to assess the status and trends of the HIV epidemic in populations and guide and assess the impact of prevention interventions. METHODS: Several methods exist for estimating population-level HIV incidence: direct observation of HIV incidence through longitudinal follow-up of persons at risk for new HIV infection, indirect measurement of HIV incidence using data on HIV prevalence and mortality in a population, and direct measurement of HIV incidence through use of tests for recent infection (TRIs) that can differentiate 'recent' from 'non-recent' infections based on biomarkers in cross-sectional specimens. Given the limitations in measuring directly observed incidence and the assumptions needed for indirect measurements of incidence, there is an increasing demand for TRIs for HIV incidence surveillance and program monitoring and evaluation purposes. RESULTS: Over ten years since the introduction of the first TRI, a number of low-, middle-, and high-income countries have integrated this method into their HIV surveillance systems to monitor HIV incidence in the population. However, the accuracy of these assays for measuring HIV incidence has been unsatisfactory to date, mainly due to misclassification of chronic infections as recent infection on the assay. To improve the accuracy of TRIs for measuring incidence, countries are recommended to apply case-based adjustments, formula-based adjustments using local correction factors, or laboratory-based adjustment to minimize error related to assay misclassification. Multiple tests may be used in a recent infection testing algorithm (RITA) to obtain more accurate HIV incidence estimates. CONCLUSION: There continues to be a high demand for improved TRIs and RITAs to monitor HIV incidence, determine prevention priorities, and assess impact of interventions. Current TRIs have noted limitations, but with appropriate adjustments, interpreted in parallel with other epidemiologic data, may still provide useful information on new infections in a population. New TRIs and RITAs with improved accuracy and performance are needed and development of these tools should be supported.