HIV Vaccine Trials Network: activities and achievements of the first decade and beyond

Foundations for improved vaccine correlate of risk analysis using positive-unlabeled learning

Insights into mechanisms of protection afforded by vaccine efficacy field trials can be complicated by both low rates of exposure and protection. However, these barriers do not preclude the discovery of correlates of reduced risk (CoR) of infection, which are a critical first step in defining correlates of protection (CoP). Given the significant investment in large-scale human vaccine efficacy trials and immunogenicity data collected to support CoR discovery, novel approaches for analyzing efficacy trials to optimally support discovery of CoP are critically needed. By simulating immunological data and evaluating several machine learning approaches, this study lays the groundwork for deploying Positive/Unlabeled (P/U) learning methods, which are designed to differentiate between two groups in cases where only one group has a definitive label and the other remains ambiguous. This description applies to case-control analysis designs for field trials of vaccine efficacy: infected subjects, or cases, are by definition unprotected, whereas uninfected subjects, or controls, may have been either protected or unprotected but simply never exposed. Here, we investigate the value of applying P/U learning to classify study subjects using model immunogenicity data based on predicted protection status in order to support new insights into mechanisms of vaccine-mediated protection from infection. We demonstrate that P/U learning methods can reliably infer protection status, supporting the discovery of simulated CoP that are not observed in conventional comparisons of infection status cases and controls, and we propose next steps necessary for the practical deployment of this novel approach to correlate discovery.

A qualitative study of stakeholder and researcher perspectives of community engagement practices for HIV vaccine clinical trials in South Africa

Community engagement increases community trust of research and improves trial participation. However, there is limited documented appraisal of community engagement practices. Several HIV vaccine efficacy trials have been conducted in South Africa, the country most affected by HIV, predominantly in collaboration with the HIV Vaccine Trials Network (HVTN). We explored stakeholder and researcher perspectives of the HVTN community engagement practices used in the Gauteng province of South Africa. In 2017, we conducted a qualitative study. Using semi-structured interview guides, we facilitated two group discussions with Community Advisory Board (CAB) members (n = 13), and 14 in-depth interviews with HVTN-affiliated employees (n = 8 in South Africa and n = 6 in the USA). Group discussions and in-depth interviews were audio-recorded, transcribed verbatim, translated into English, and coded using NVIVO 12 Plus software for thematic data analysis. Overall, median age of study participants was 22 (interquartile range 32-54) years, and 74% (n = 20) were female. Three main themes about community engagement emerged: (i) community engagement as an ongoing iterative relationship between researchers and community; (ii) methods of community engagement, encompassing community education by linking with external stakeholders and through awareness campaigns by pamphlet distribution and mass events, working with communities to develop recruitment messages, and working with CAB as a link to communities; and (iii) strategies to improve community engagement, for example, using simple language, linking with religious leaders and traditional healers, and communicating via conventional (newspapers, television, and radio) and social (videos and listicles) media. Our data indicate ways for researchers to improve relationships with community by understanding local needs, strengthening collaborations, and tailoring communication strategies. In this regard, CABs signify critical linkages between researchers and communities. CABs can relay relevant health research needs, advise on the creation of suitable materials, and link researchers more effectively with community leaders and media.

Leveraging lessons learned from the COVID-19 pandemic for HIV

The rapid development of COVID-19 vaccines and their deployment in less than a year is an unprecedented scientific, medical, and public health achievement. This rapid development leveraged knowledge from decades of HIV/AIDS research and advances. However, the search for an HIV vaccine that would contribute to a durable end to the HIV pandemic remains elusive. Here, we draw from the US government experience and highlight lessons learned from COVID-19 vaccine development, which include the importance of public-private partnerships, equitable inclusion of populations impacted by the infectious pathogen, and continued investment in basic research. We summarize key considerations for an accelerated and re-energized framework for developing a safe and efficacious HIV vaccine.

Calder, Tong et al. discuss how the rapid development of COVID-19 vaccines benefited from HIV/AIDS research. They highlight lessons learned from the COVID-19 vaccine development experience that could accelerate and re-energize the development of a safe and efficacious HIV vaccine.

Adjuvant-mediated enhancement of the immune response to HIV vaccines

Protection from human immunodeficiency virus (HIV) acquisition will likely require an effective vaccine that elicits antibodies against the HIV-1 envelope glycoproteins (Envs), which are the sole target of neutralizing antibodies and a main focus of vaccine development. Adjuvants have been widely used to augment the magnitude and longevity of the adaptive immune responses to immunizations with HIV-1 Envs and to guide the development of specific immune responses. Here, we review the adjuvants that have been used in combination with HIV-1 Envs in several preclinical and human clinical trials in recent years. We summarize the interactions between the HIV-1 Envs and adjuvants, and highlight the routes of vaccine administration for various formulations. We then discuss the use of combinations of different adjuvants, the potential effect of adjuvants on the elicitation of antibodies enriched in somatic hypermutation and containing long complementarity-determining region 3 of the antibody heavy chain, and the elicitation of non-neutralizing antibodies.

Performance of International AIDS Vaccine Initiative African clinical research laboratories in standardised ELISpot and peripheral blood mononuclear cell processing in support of HIV vaccine clinical trials

Background

Standardisation of procedures for performing cellular functional assays across laboratories participating in multicentre clinical trials is key for generating comparable and reliable data.

Objective

This article describes the performance of accredited laboratories in Africa and Europe on testing done in support of clinical trials.

Methods

For enzyme-linked immunospot assay (ELISpot) proficiency, characterised peripheral blood mononuclear cells (PBMCs) obtained from 48 HIV-negative blood donors in Johannesburg, South Africa, were sent to participating laboratories between February 2010 and February 2014. The PBMCs were tested for responses against cytomegalovirus, Epstein Barr and influenza peptide pools in a total of 1751 assays. In a separate study, a total of 1297 PBMC samples isolated from healthy HIV-negative participants in clinical trials of two prophylactic HIV vaccine candidates in Kenya, Uganda, Rwanda and Zambia were analysed for cell viability, cell yield and cell recovery from frozen PBMCs.

Results

Most (99%) of the 1751 ELISpot proficiency assays had data within acceptable ranges with low responses to mock stimuli. No significant statistical difference were observed in ELISpot responses at the five laboratories actively conducting immunological analyses. Of the 1297 clinical trial PBMCs processed, 94% had cell viability above 90% and 96% had cell yield above 0.7 million per mL of blood in freshly isolated cells. All parameters were within the predefined acceptance criteria.

Conclusion

We demonstrate that multiple laboratories can generate reliable, accurate and comparable data by using standardised procedures, having regular training, having regular equipment maintenance and using centrally sourced reagents.

Research productivity and collaboration of the NIH-funded HIV vaccine trials network: A bibliometric analysis

The HIV Vaccine Trials Network (HVTN) is the world's largest publicly funded, multi-disciplinary international collaboration facilitating the development of vaccines to prevent HIV/AIDS and has conducted the vast majority of HIV/AIDS clinical trials since its inception in 1999. Although scientific findings from the program have been published in scholarly journals, the impact of a large scientific research network such as the HVTN on the HIV/AIDS vaccine field has not been assessed. This paper describes and elucidates the productivity, influence, and collaboration among HVTN researchers over the last two decades. Our analyses indicate that the HVTN has funded a large number of HIV/AIDS vaccine safety and efficacy clinical trials through a strong global network of clinical sites. In addition, several metrics indicate HVTN researchers also published original research articles that are influential in the HIV vaccine field. Scientific research collaboration is critically important in a complex and multidisciplinary field such as HIV vaccine development as it allows improved sharing of knowledge and expertise as well as the pooling of resources and data. We found that collaboration in the HIV vaccine field increased during this time period and collaboration among HVTN authors increased even more. Combining these productivity, influence, and collaboration metrics with research outcomes can provide a comprehensive assessment of large complex programs such as the HVTN.

Stakeholder engagement to inform HIV clinical trials: a systematic review of the evidence

INTRODUCTION

Stakeholder engagement is an essential component of HIV clinical trials. We define stakeholder engagement as an input by individuals or groups with an interest in HIV clinical trials to inform the design or conduct of said trials. Despite its value, stakeholder engagement to inform HIV clinical trials has not been rigorously examined. The purpose of our systematic review is to examine stakeholder engagement for HIV clinical trials and compare it to the recommendations of the UNAIDS/AVAC Good Participatory Practice (GPP) guidelines.

METHODS

We used the PRISMA checklist and identified English language studies describing stakeholder engagement to inform HIV clinical trials. Four databases (PubMed, Ovid, CINAHL and Web of Science) and six journals were searched, with additional studies identified using handsearching and expert input. Two independent reviewers examined citations, abstracts and full texts. Data were extracted on country, engagement methods, stakeholder types and purpose of stakeholder engagement. Based on the GPP guidelines, we examined how frequently stakeholder engagement was conducted to inform clinical trial research question development, protocol development, recruitment, enrolment, follow-up, results and dissemination.

RESULTS AND DISCUSSION

Of the 917 citations identified, 108 studies were included in the analysis. Forty-eight studies (44.4%) described stakeholder engagement in high-income countries, thirty (27.8%) in middle-income countries and nine (8.3%) in low-income countries. Fourteen methods for stakeholder engagement were identified, including individual (e.g. interviews) and group (e.g. community advisory boards) strategies. Thirty-five types of stakeholders were engaged, with approximately half of the studies (60; 55.6%) engaging HIV-affected community stakeholders (e.g. people living with HIV, at-risk or related populations of interest). We observed greater frequency of stakeholder engagement to inform protocol development (49 studies; 45.4%) and trial recruitment (47 studies; 43.5%). Fewer studies described stakeholder engagement to inform post-trial processes related to trial results (3; 2.8%) and dissemination (11; 10.2%).

CONCLUSIONS

Our findings identify important directions for future stakeholder engagement research and suggestions for policy. Most notably, we found that stakeholder engagement was more frequently conducted to inform early stages of HIV clinical trials compared to later stages. In order to meet recommendations established in the GPP guidelines, greater stakeholder engagement across all clinical trial stages is needed.

Vaccine development for syphilis

INTRODUCTION

Syphilis, caused by the spirochete Treponema pallidum subspecies pallidum, continues to be a globally prevalent disease despite remaining susceptible to penicillin treatment. Syphilis vaccine development is a viable preventative approach that will serve to complement public health-oriented syphilis prevention, screening and treatment initiatives to deliver a two-pronged approach to stemming disease spread worldwide. Areas covered: This article provides an overview of the need for development of a syphilis vaccine, summarizes significant information that has been garnered from prior syphilis vaccine studies, discusses the critical aspects of infection that would have to be targeted by a syphilis vaccine, and presents the current understanding within the field of the correlates of protection needed to be achieved through vaccination. Expert commentary: Syphilis vaccine development should be considered a priority by industry, regulatory and funding agencies, and should be appropriately promoted and supported.

Infectious Diseases

The objectives of this chapter are to provide a brief understanding of the following:1.

Clinical evaluation of infectious diseases and altered immune disorders, including physical examination and laboratory studies

2.

Various infectious disease processes, including etiology, pathogenesis, clinical presentation, and management

3.

Commonly encountered altered immune disorders, including etiology, clinical presentation, and management

4.

Precautions and guidelines that a physical therapist should implement when treating a patient with an infectious disease process or altered immunity

Novel directions in HIV-1 vaccines revealed from clinical trials

PURPOSE OF REVIEW

Considerable HIV-1 vaccine development efforts have been deployed over the past decade. Put into perspective, the results from efficacy trials and the identification of correlates of risk have opened large and unforeseen avenues for vaccine development.

RECENT FINDINGS

The Thai efficacy trial, RV144, provided the first evidence that HIV-1 vaccine protection against HIV-1 acquisition could be achieved. The correlate of risk analysis showed that IgG antibodies against the gp120 V2 loop inversely correlated with a decreased risk of infection, whereas Env-specific IgA directly correlated with risk. Further clinical trials will focus on testing new envelope subunit proteins formulated with adjuvants capable of inducing higher and more durable functional antibody responses (both binding and broadly neutralizing antibodies). Moreover, vector-based vaccine regimens that can induce cell-mediated immune responses in addition to humoral responses remain a priority.

SUMMARY

Future efficacy trials will focus on prevention of HIV-1 transmission in heterosexual population in Africa and MSM in Asia. The recent successes leading to novel directions in HIV-1 vaccine development are a result of collaboration and commitment among vaccine manufacturers, funders, scientists and civil society stakeholders. Sustained and broad collaborative efforts are required to advance new vaccine strategies for higher levels of efficacy.

A brief history of the global effort to develop a preventive HIV vaccine

Soon after HIV was discovered as the cause of AIDS in 1983-1984, there was an expectation that a preventive vaccine would be rapidly developed. In trying to achieve that goal, three successive scientific paradigms have been explored: induction of neutralizing antibodies, induction of cell mediated immunity, and exploration of combination approaches and novel concepts. Although major progress has been made in understanding the scientific basis for HIV vaccine development, efficacy trials have been critical in moving the field forward. In 2009, the field was reinvigorated with the modest results obtained from the RV144 trial conducted in Thailand. Here, we review those vaccine development efforts, with an emphasis on events that occurred during the earlier years. The goal is to provide younger generations of scientists with information and inspiration to continue the search for an HIV vaccine.