RNA vaccines: A transformational advance

Vaccines have stemmed many infectious diseases, but when SARS-CoV-2 emerged, traditional vaccine development would not have been fast enough. This year's Nobel Prize in Physiology or Medicine recognizes work that enabled the rapid development of mRNA vaccines, which halted the COVID-19 pandemic. The feat was a product of basic biological insights coupled with technological innovations, which have transformed vaccine design.

What keeps me up at night

The lessons of COVID-19 must be heeded if the world is to be prepared for the next emergent pathogen with pandemic potential.

Pandemic Preparedness and Response: Lessons From COVID-19

The global experience with COVID-19 holds important lessons for preparing for, and responding to, future emergences of pathogens with pandemic potential.

Increased neutralization potency and breadth elicited by a SARS-CoV-2 mRNA vaccine forming virus-like particles

Vaccines have played a fundamental role in the control of infectious diseases. We previously developed a messenger RNA (mRNA) vaccine against HIV-1 that forms virus-like particles (VLPs) through coexpression of the viral envelope with Gag. Here, we applied the same principle to the design of a VLP-forming mRNA vaccine against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). To promote cognate interaction with simian immunodeficiency virus (SIV) Gag, we engineered different chimeric proteins encompassing the ectodomain and the transmembrane region of the SARS-CoV-2 Spike protein from the Wuhan-Hu-1 strain fused to the gp41 cytoplasmic tail of either HIV-1 (strain WITO) or SIV (strain mac239) with or without a partial truncation at amino acid 745 to enhance membrane expression. Upon cotransfection with SIV gag mRNA, the Spike-SIVCT.745 (SSt) chimera yielded the highest level of cell-surface expression and extracellular VLP release. Immunization of BALB/c mice with SSt+gag mRNA at 0, 4, and 16 wk induced higher titers of Spike-binding and autologous neutralizing antibodies at all time points compared to SSt mRNA alone. Furthermore, mice immunized with SSt+gag mRNA developed neutralizing antibodies effective against different variants of concern. These data demonstrate that the Gag/VLP mRNA platform can be successfully applied to vaccines against different agents for the prevention of infectious diseases of global relevance.

Prototype Pathogen Approach for Vaccine and Monoclonal Antibody Development: A Critical Component of the NIAID Plan for Pandemic Preparedness

Severe acute respiratory syndrome coronavirus 1 (SARS-CoV-1) emerged 20 years ago, presaging a series of subsequent infectious disease epidemics of international concern. The recent emergence of SARS-CoV-2 has underscored the importance of targeted preparedness research to enable rapid countermeasure development during a crisis. In December 2021 the National Institute of Allergy and Infectious Diseases (NIAID), building upon the successful strategies developed during the SARS-CoV-2 response and to prepare for future pandemics, published a pandemic preparedness plan that outlined a research strategy focused on priority pathogens, technology platforms, and prototype pathogens. To accelerate the discovery, development, and evaluation of medical countermeasures against new or previously unknown pathogens of pandemic potential, we present here a strategy of research directed at select prototype pathogens. In this manner, leveraging a prototype pathogen approach may serve as a powerful cornerstone in biomedical research preparedness to protect public health from newly emerging and reemerging infectious diseases.

MAdCAM-1 costimulation in the presence of retinoic acid and TGF-β promotes HIV infection and differentiation of CD4+ T cells into CCR5+ TRM-like cells

CD4+ tissue resident memory T cells (TRMs) are implicated in the formation of persistent HIV reservoirs that are established during the very early stages of infection. The tissue-specific factors that direct T cells to establish tissue residency are not well defined, nor are the factors that establish viral latency. We report that costimulation via MAdCAM-1 and retinoic acid (RA), two constituents of gut tissues, together with TGF-β, promote the differentiation of CD4+ T cells into a distinct subset α4β7+CD69+CD103+ TRM-like cells. Among the costimulatory ligands we evaluated, MAdCAM-1 was unique in its capacity to upregulate both CCR5 and CCR9. MAdCAM-1 costimulation rendered cells susceptible to HIV infection. Differentiation of TRM-like cells was reduced by MAdCAM-1 antagonists developed to treat inflammatory bowel diseases. These finding provide a framework to better understand the contribution of CD4+ TRMs to persistent viral reservoirs and HIV pathogenesis.

Rethinking next-generation vaccines for coronaviruses, influenzaviruses, and other respiratory viruses

Viruses that replicate in the human respiratory mucosa without infecting systemically, including influenza A, SARS-CoV-2, endemic coronaviruses, RSV, and many other "common cold" viruses, cause significant mortality and morbidity and are important public health concerns. Because these viruses generally do not elicit complete and durable protective immunity by themselves, they have not to date been effectively controlled by licensed or experimental vaccines. In this review, we examine challenges that have impeded development of effective mucosal respiratory vaccines, emphasizing that all of these viruses replicate extremely rapidly in the surface epithelium and are quickly transmitted to other hosts, within a narrow window of time before adaptive immune responses are fully marshaled. We discuss possible approaches to developing next-generation vaccines against these viruses, in consideration of several variables such as vaccine antigen configuration, dose and adjuventation, route and timing of vaccination, vaccine boosting, adjunctive therapies, and options for public health vaccination polices.

Anti-PF4 antibodies associated with disease severity in COVID-19

Severe COVID-19 is characterized by a prothrombotic state associated with thrombocytopenia, with microvascular thrombosis being almost invariably present in the lung and other organs at postmortem examination. We evaluated the presence of antibodies to platelet factor 4 (PF4)-polyanion complexes using a clinically validated immunoassay in 100 hospitalized patients with COVID-19 with moderate or severe disease (World Health Organization score, 4 to 10), 25 patients with acute COVID-19 visiting the emergency department, and 65 convalescent individuals. Anti-PF4 antibodies were detected in 95 of 100 hospitalized patients with COVID-19 (95.0%) irrespective of prior heparin treatment, with a mean optical density value of 0.871 ± 0.405 SD (range, 0.177 to 2.706). In contrast, patients hospitalized for severe acute respiratory disease unrelated to COVID-19 had markedly lower levels of the antibodies. In a high proportion of patients with COVID-19, levels of all three immunoglobulin (Ig) isotypes tested (IgG, IgM, and IgA) were simultaneously elevated. Antibody levels were higher in male than in female patients and higher in African Americans and Hispanics than in White patients. Anti-PF4 antibody levels were correlated with the maximum disease severity score and with significant reductions in circulating platelet counts during hospitalization. In individuals convalescent from COVID-19, the antibody levels returned to near-normal values. Sera from patients with COVID-19 induced higher levels of platelet activation than did sera from healthy blood donors, but the results were not correlated with the levels of anti-PF4 antibodies. These results demonstrate that the vast majority of patients with severe COVID-19 develop anti-PF4 antibodies, which may play a role in the clinical complications of COVID-19.

Interval between prior SARS-CoV-2 infection and booster vaccination impacts magnitude and quality of antibody and B cell responses

SARS-CoV-2 mRNA booster vaccines provide protection from severe disease, eliciting strong immunity that is further boosted by previous infection. However, it is unclear whether these immune responses are affected by the interval between infection and vaccination. Over a 2-month period, we evaluated antibody and B cell responses to a third-dose mRNA vaccine in 66 individuals with different infection histories. Uninfected and post-boost but not previously infected individuals mounted robust ancestral and variant spike-binding and neutralizing antibodies and memory B cells. Spike-specific B cell responses from recent infection (<180 days) were elevated at pre-boost but comparatively less so at 60 days post-boost compared with uninfected individuals, and these differences were linked to baseline frequencies of CD27^lo B cells. Day 60 to baseline ratio of BCR signaling measured by phosphorylation of Syk was inversely correlated to days between infection and vaccination. Thus, B cell responses to booster vaccines are impeded by recent infection.

Recent SARS-CoV-2 infection abrogates antibody and B-cell responses to booster vaccination

SARS-CoV-2 mRNA booster vaccines provide protection from severe disease, eliciting strong immunity that is further boosted by previous infection. However, it is unclear whether these immune responses are affected by the interval between infection and vaccination. Over a two-month period, we evaluated antibody and B-cell responses to a third dose mRNA vaccine in 66 individuals with different infection histories. Uninfected and post-boost but not previously infected individuals mounted robust ancestral and variant spike-binding and neutralizing antibodies, and memory B cells. Spike-specific B-cell responses from recent infection were elevated at pre-boost but comparatively less so at 60 days post-boost compared to uninfected individuals, and these differences were linked to baseline frequencies of CD27 lo B cells. Day 60 to baseline ratio of BCR signaling measured by phosphorylation of Syk was inversely correlated to days between infection and vaccination. Thus, B-cell responses to booster vaccines are impeded by recent infection.

Combination anti-HIV antibodies provide sustained virological suppression

Antiretroviral therapy is highly effective in suppressing human immunodeficiency virus (HIV)1. However, eradication of the virus in individuals with HIV has not been possible to date2. Given that HIV suppression requires life-long antiretroviral therapy, predominantly on a daily basis, there is a need to develop clinically effective alternatives that use long-acting antiviral agents to inhibit viral replication3. Here we report the results of a two-component clinical trial involving the passive transfer of two HIV-specific broadly neutralizing monoclonal antibodies, 3BNC117 and 10-1074. The first component was a randomized, double-blind, placebo-controlled trial that enrolled participants who initiated antiretroviral therapy during the acute/early phase of HIV infection. The second component was an open-label single-arm trial that enrolled individuals with viraemic control who were naive to antiretroviral therapy. Up to 8 infusions of 3BNC117 and 10-1074, administered over a period of 24 weeks, were well tolerated without any serious adverse events related to the infusions. Compared with the placebo, the combination broadly neutralizing monoclonal antibodies maintained complete suppression of plasma viraemia (for up to 43 weeks) after analytical treatment interruption, provided that no antibody-resistant HIV was detected at the baseline in the study participants. Similarly, potent HIV suppression was seen in the antiretroviral-therapy-naive study participants with viraemia carrying sensitive virus at the baseline. Our data demonstrate that combination therapy with broadly neutralizing monoclonal antibodies can provide long-term virological suppression without antiretroviral therapy in individuals with HIV, and our experience offers guidance for future clinical trials involving next-generation antibodies with long half-lives.

Update on and Future Directions for Use of Anti-SARS-CoV-2 Antibodies: National Institutes of Health Summit on Treatment and Prevention of COVID-19

As the fourth wave of the SARS-CoV-2 pandemic encircles the globe, there remains an urgent challenge to identify safe and effective treatment and prevention strategies that can be implemented in a range of health care and clinical settings. Substantial advances have been made in the use of anti-SARS-CoV-2 antibodies to mitigate the morbidity and mortality associated with COVID-19. On 15 June 2021, the National Institutes of Health, in collaboration with the U.S. Food and Drug Administration, convened a virtual summit to summarize existing knowledge on anti-SARS-CoV-2 antibodies and to identify key unanswered scientific questions to further catalyze the clinical development and implementation of antibodies.

A multiclade env-gag VLP mRNA vaccine elicits tier-2 HIV-1-neutralizing antibodies and reduces the risk of heterologous SHIV infection in macaques

The development of a protective vaccine remains a top priority for the control of the HIV/AIDS pandemic. Here, we show that a messenger RNA (mRNA) vaccine co-expressing membrane-anchored HIV-1 envelope (Env) and simian immunodeficiency virus (SIV) Gag proteins to generate virus-like particles (VLPs) induces antibodies capable of broad neutralization and reduces the risk of infection in rhesus macaques. In mice, immunization with co-formulated env and gag mRNAs was superior to env mRNA alone in inducing neutralizing antibodies. Macaques were primed with a transmitted-founder clade-B env mRNA lacking the N276 glycan, followed by multiple booster immunizations with glycan-repaired autologous and subsequently bivalent heterologous envs (clades A and C). This regimen was highly immunogenic and elicited neutralizing antibodies against the most prevalent (tier-2) HIV-1 strains accompanied by robust anti-Env CD4+ T cell responses. Vaccinated animals had a 79% per-exposure risk reduction upon repeated low-dose mucosal challenges with heterologous tier-2 simian-human immunodeficiency virus (SHIV AD8). Thus, the multiclade env-gag VLP mRNA platform represents a promising approach for the development of an HIV-1 vaccine.

Human Immunodeficiency Virus/AIDS in the Era of Coronavirus Disease 2019: A Juxtaposition of 2 Pandemics

The coronavirus disease 2019 (COVID-19) pandemic has significantly impacted persons with human immunodeficiency virus (HIV), interfering with critical health services for HIV prevention, treatment, and care. While there are multiple profiles of persons living with HIV and the impact of COVID-19 may differ for each, the severity of COVID-19 in persons with HIV is related strongly to the presence of comorbidities that increase the risk of severe disease in COVID-19 patients in the absence of HIV. An effective response to the juxtaposition of the HIV and COVID-19 pandemics requires a novel coordinated and collaborative global effort of scientists, industry, and community partners to accelerate basic and clinical research, as well as implementation science to operationalize evidence-based interventions expeditiously in real-world settings. Accelerated development and clinical evaluation of prevention and treatment countermeasures are urgently needed to mitigate the juxtaposition of the HIV and COVID-19 pandemics.

Blocking α4β7 integrin delays viral rebound in SHIVSF162P3-infected macaques treated with anti-HIV broadly neutralizing antibodies

Anti-HIV broadly neutralizing antibodies (bNAbs) may favor development of antiviral immunity by engaging the immune system during immunotherapy. Targeting integrin α4β7 with an anti-α4β7 monoclonal antibody (Rh-α4β7) affects immune responses in SIV/SHIV-infected macaques. To explore the therapeutic potential of combining bNAbs with α4β7 integrin blockade, SHIVSF162P3-infected, viremic rhesus macaques were treated with bNAbs only (VRC07-523LS and PGT128 anti-HIV antibodies) or a combination of bNAbs and Rh-α4β7 or were left untreated as a control. Treatment with bNAbs alone decreased viremia below 200 copies/ml in all macaques, but seven of eight macaques (87.5%) in the bNAbs-only group rebounded within a median of 3 weeks (95% CI: 2 to 9). In contrast, three of six macaques treated with a combination of Rh-α4β7 and bNAbs (50%) maintained a viremia below 200 copies/ml until the end of the follow-up period; viremia in the other three macaques rebounded within a median of 6 weeks (95% CI: 5 to 11). Thus, there was a modest delay in viral rebound in the macaques treated with the combination antibody therapy compared to bNAbs alone. Our study suggests that α4β7 integrin blockade may prolong virologic control by bNAbs in SHIVSF162P3-infected macaques.

Report of the National Institutes of Health SARS-CoV-2 Antiviral Therapeutics Summit

The NIH Virtual SARS-CoV-2 Antiviral Summit, held on 6 November 2020, was organized to provide an overview on the status and challenges in developing antiviral therapeutics for coronavirus disease 2019 (COVID-19), including combinations of antivirals. Scientific experts from the public and private sectors convened virtually during a live videocast to discuss severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) targets for drug discovery as well as the preclinical tools needed to develop and evaluate effective small-molecule antivirals. The goals of the Summit were to review the current state of the science, identify unmet research needs, share insights and lessons learned from treating other infectious diseases, identify opportunities for public-private partnerships, and assist the research community in designing and developing antiviral therapeutics. This report includes an overview of therapeutic approaches, individual panel summaries, and a summary of the discussions and perspectives on the challenges ahead for antiviral development.

Pre-vaccination and early B cell signatures predict antibody response to SARS-CoV-2 mRNA vaccine

SARS-CoV-2 mRNA vaccines are highly effective, although weak antibody responses are seen in some individuals with correlates of immunity that remain poorly understood. Here we longitudinally dissected antibody, plasmablast, and memory B cell (MBC) responses to the two-dose Moderna mRNA vaccine in SARS-CoV-2-uninfected adults. Robust, coordinated IgA and IgG antibody responses were preceded by bursts of spike-specific plasmablasts after both doses, but earlier and more intensely after dose two. Distinct antigen-specific MBC populations also emerged post-vaccination with varying kinetics. We identified antigen non-specific pre-vaccination MBC and post-vaccination plasmablasts after dose one and their spike-specific counterparts early after dose two that correlated with subsequent antibody levels. These baseline and response signatures can thus provide early indicators of serological efficacy and explain response variability in the population.

A Centenary Tale of Two Pandemics: The 1918 Influenza Pandemic and COVID-19, Part II

Both the 1918 influenza pandemic and the 2019‒2021 COVID-19 pandemic are among the most disastrous infectious disease emergences of modern times. In addition to similarities in their clinical, pathological, and epidemiological features, the two pandemics, separated by more than a century, were each met with essentially the same, or very similar, public health responses, and elicited research efforts to control them with vaccines, therapeutics, and other medical approaches. Both pandemics had lasting, if at times invisible, psychosocial effects related to loss and hardship. In considering these two deadly pandemics, we ask: what lessons have we learned over the span of a century, and how are we applying those lessons to the challenges of COVID-19?

A Centenary Tale of Two Pandemics: The 1918 Influenza Pandemic and COVID-19, Part I

Separated by a century, the influenza pandemic of 1918 and the COVID-19 pandemic of 2019-2021 are among the most disastrous infectious disease emergences of modern times. Although caused by unrelated viruses, the two pandemics are nevertheless similar in their clinical, pathological, and epidemiological features, and in the civic, public health, and medical responses to combat them. Comparing and contrasting the two pandemics, we consider what lessons we have learned over the span of a century and how we are applying those lessons to the challenges of COVID-19.

SARS-CoV-2 Vaccines: Much Accomplished, Much to Learn

As COVID vaccines roll out, internists and other health care providers are being turned to as trusted sources of information for patients and communities. Here, experts from NIAID outline the current state of knowledge regarding such vaccines. They contrast vaccine platforms, summarize clinical trial data regarding efficacy and safety, and comment on key questions including the ability of current vaccines to protect against infection and to decrease the prevalence of virus in the community.

COVID-19: The therapeutic landscape

Therapeutics for hospitalized COVID-19 patients were identified through a robust research response with several lessons learned: clinical trial data should guide therapeutic use, results should not be extrapolated between disease stages, and robust studies should be designed to give clinically relevant data. These lessons should be applied to the outpatient research response.

Kinetics of Plasma HIV Rebound in the Era of Modern Antiretroviral Therapy

Historical data regarding time to viral rebound following analytical treatment interruption (ATI) have been used to determine therapeutic efficacy in HIV cure trials; however, such data were collected from studies conducted a decade or more ago and included participants receiving older antiretroviral therapy (ART) regimens with infrequent virologic monitoring. We conducted a study of 22 HIV-infected participants receiving modern ART to determine the kinetics of plasma viral rebound following ATI. Our data suggest that modern ART does not alter kinetics of viral rebound when compared to previous regimens and that immunologic interventions may be necessary to achieve ART-free virologic remission. Clinical Trials Registration ClinicaTrials.gov identifier: NCT03225118.

Refocusing Research on Sexually Transmitted Infections

This article highlights biomedical research goals for the development of critical tools, including innovative diagnostics, safe and effective vaccines, and new and improved therapeutics, necessary to achieve an end to the global epidemic of sexually transmitted infections. The incidence of sexually transmitted infections (STIs), including gonorrhea, syphilis, chlamydia, and trichomoniasis, is increasing by over 1 million new cases daily and represents a global public health crisis. There is an alarming increase of gonorrhea and syphilis among men who have sex with men and bisexual men, 2 key populations also at high risk for human immunodeficiency virus. A refocused, dedicated, and intensive biomedical research program is needed targeting development of innovative diagnostics, safe and effective vaccines, and new and improved therapeutics. This article highlights biomedical research goals providing critical tools necessary to achieve an end to the global STIs epidemic.

Refocusing Human Microbiota Research in Infectious and Immune-mediated Diseases: Advancing to the Next Stage

Changes in the microbiota are associated with disease susceptibility, immune system development, and responses to treatment. Refocusing research to elucidate the causal links between the human microbiota and infectious and immune-mediated diseases will be critical to harnessing its power to prevent, diagnose, and treat such diseases.

2019: A Banner Year for Tuberculosis Research

This article outlines the significant scientific progress reported in 2019 that has led to the development of new drugs and therapeutic regimens, vaccine candidates, and diagnostics for the prevention and treatment of tuberculosis. In 2020, it will be important to build on this momentum and continue to advance basic and clinical research to develop improved tools and interventions, simultaneously optimizing their implementation in national control programs. To successfully achieve the goal to end tuberculosis within a generation, a concerted, collective, and collaborative effort is required, involving government, academia, industry and civil society at all levels.

Ending the Human Immunodeficiency Virus Pandemic: Optimizing the Prevention and Treatment Toolkits

Unprecedented basic and clinical biomedical research advances over the past 4 decades have led to the development of "toolkits" of highly effective interventions for preventing and treating human immunodeficiency virus (HIV). Despite many successes in decreasing the incidence and mortality of HIV, major challenges remain in the goal of ending the HIV pandemic in the United States and globally. Overcoming these challenges will require optimization of the implementation of existing interventions for HIV prevention and treatment together with the continued development of new and innovative approaches that can be readily utilized by individuals with HIV and those at risk of infection.

Emerging Pandemic Diseases: How We Got to COVID-19

Infectious diseases prevalent in humans and animals are caused by pathogens that once emerged from other animal hosts. In addition to these established infections, new infectious diseases periodically emerge. In extreme cases they may cause pandemics such as COVID-19; in other cases, dead-end infections or smaller epidemics result. Established diseases may also re-emerge, for example by extending geographically or by becoming more transmissible or more pathogenic. Disease emergence reflects dynamic balances and imbalances, within complex globally distributed ecosystems comprising humans, animals, pathogens, and the environment. Understanding these variables is a necessary step in controlling future devastating disease emergences.