After a 1960s RSV vaccine was found to enhance disease in previously unexposed infants, development was put on hold. But structure-based design has led to effective RSV vaccines that now await ...approval.
Respiratory syncytial virus (RSV) is an important cause of respiratory disease causing high rates of hospitalizations in infants, significant morbidity in children and adults, and excess mortality in ...the elderly. Major barriers to vaccine development include early age of RSV infection, capacity of RSV to evade innate immunity, failure of RSV‐induced adaptive immunity to prevent reinfection, history of RSV vaccine‐enhanced disease, and lack of an animal model fully permissive to human RSV infection. These biological challenges, safety concerns, and practical issues have significantly prolonged the RSV vaccine development process. One great advantage compared to other difficult viral vaccine targets is that passively administered neutralizing monoclonal antibody is known to protect infants from severe RSV disease. Therefore, the immunological goals for vaccine development are to induce effective neutralizing antibody to prevent infection and to avoid inducing T‐cell response patterns associated with enhanced disease. Live‐attenuated RSV and replication‐competent chimeric viruses are in advanced clinical trials. Gene‐based strategies, which can control the specificity and phenotypic properties of RSV‐specific T‐cell responses utilizing replication‐defective vectors and which may improve on immunity from natural infection, are progressing through preclinical testing. Atomic level structural information on RSV envelope glycoproteins in complex with neutralizing antibodies is guiding design of new vaccine antigens that may be able to elicit RSV‐specific antibody responses without induction of RSV‐specific T‐cell responses. These new technologies may allow development of vaccines that can protect against RSV‐mediated disease in infants and establish a new immunological paradigm in the host to achieve more durable protection against reinfection.
•RSV is an important cause of lower respiratory tract infection and disease at the extremes of age.•The RSV fusion (F) glycoprotein is the major target for virus neutralizing antibodies.•Recent ...breakthroughs in defining the structure of F in its prefusion state identified new neutralization-sensitive epitopes.•Stabilizing F in the prefusion conformation improves immunogenicity and is the basis for a leading candidate vaccine antigen.•Structure-based vaccine antigen design and other technological advances have made vaccine development for RSV and other viral diseases more feasible.
Respiratory syncytial virus (RSV) is an important and ubiquitous respiratory pathogen for which no vaccine is available notwithstanding more than 50 years of effort. It causes the most severe disease at the extremes of age and in settings of immunodeficiency. Although RSV is susceptible to neutralizing antibody, it has evolved multiple mechanisms of immune evasion allowing it to repeatedly infect people despite relatively little genetic diversity. Recent breakthroughs in determining the structure and antigenic content of the fusion (F) glycoprotein in its metastable untriggered prefusion form (pre-F) and the stable rearranged postfusion form (post-F) have yielded vaccine strategies that can induce potent neutralizing antibody responses and effectively boost pre-existing neutralizing activity. In parallel, novel live-attenuated and chimeric virus vaccine candidates and other novel approaches to deliver vaccine antigens have been developed. These events and activities have aroused optimism and a robust pipeline of potential vaccine products that promise to provide a means to reduce the public health burden of RSV infection.
The development of effective vaccines to combat infectious diseases is a complex multi-year and multi-stakeholder process. To accelerate the development of vaccines for coronavirus disease 2019 ...(COVID-19), a novel pathogen emerging in late 2019 and spreading globally by early 2020, the United States government (USG) mounted an operation bridging public and private sector expertise and infrastructure. The success of the endeavor can be seen in the rapid advanced development of multiple vaccine candidates, with several demonstrating efficacy and now being administered around the globe. Here, we review the milestones enabling the USG-led effort, the methods utilized, and ensuing outcomes. We discuss the current status of COVID-19 vaccine development and provide a perspective for how partnership and preparedness can be better utilized in response to future public-health pandemic emergencies.
The development of effective vaccines to combat infectious diseases is a complex multi-year and multi-stakeholder process. To accelerate the development of vaccines for coronavirus disease 2019 (COVID-19), a novel pathogen emerging in late 2019 and spreading globally by early 2020, the United States government (USG) mounted an operation bridging public and private sector expertise and infrastructure. The success of the endeavor can be seen in the rapid advanced development of multiple vaccine candidates, with several demonstrating efficacy and now being administered around the globe. Here, we review the milestones enabling the USG-led effort, the methods utilized, and ensuing outcomes. We discuss the current status of COVID-19 vaccine development and provide a perspective for how partnership and preparedness can be better utilized in response to future public-health pandemic emergencies.
Abstract Respiratory syncytial virus causes a significant public health burden, particularly in very young infants and the frail elderly. The legacy of enhanced RSV disease (ERD) from a whole ...formalin-inactivated RSV vaccine, and the complex biology of the virus and the neonate have delayed the development of effective vaccines. However, new insights into factors associated with ERD and breakthroughs in understanding the antigenic structure of the fusion (F) glycoprotein have increased optimism that vaccine development is possible. This has led to investment of time and resources by industry, regulatory authorities, governments, and nonprofit organizations to develop the infrastructure needed to make the advanced clinical development of RSV vaccine candidates a reality.
Summary
Antiviral vaccines have been the most successful biomedical intervention for preventing epidemic viral disease. Vaccination for smallpox in humans and rinderpest in cattle was the basis for ...disease eradication, and recent progress in polio eradication is promising. Although early vaccines were developed empirically by passage in live animals or eggs, more recent vaccines have been developed because of the advent of new technologies, particularly cell culture and molecular biology. Recent technological advances in gene delivery and expression, nanoparticles, protein manufacturing, and adjuvants have created the potential for new vaccine platforms that may provide solutions for vaccines against viral pathogens for which no interventions currently exist. In addition, the technological convergence of human monoclonal antibody isolation, structural biology, and high‐throughput sequencing is providing new opportunities for atomic‐level immunogen design. Selection of human monoclonal antibodies can identify immunodominant antigenic sites associated with neutralization and provide reagents for stabilizing and solving the structure of viral surface proteins. Understanding the structural basis for neutralization can guide selection of vaccine targets. Deep sequencing of the antibody repertoire and defining the ontogeny of the desired antibody responses can reveal the junctional recombination and somatic mutation requirements for B‐cell recognition and affinity maturation. Collectively, this information will provide new strategic approaches for selecting vaccine antigens, formulations, and regimens. Moreover, it creates the potential for rational vaccine design and establishing a catalogue of vaccine technology platforms that would be effective against any given family or class of viral pathogens and improve our readiness to address new emerging viral threats.
•Immunological goals for vaccination depend on whether it is for primary induction or boosting of pre-existing immunity.•Boosting neutralizing activity is the major goal for maternal and elderly ...populations.•High potency neutralizing activity is primarily directed to the RSV F glycoprotein and is conformation-dependent.•For antigen-naïve infants, avoidance of immunopathology is as important as induction of protective immunity.•New technologies have informed precision vaccine design and yielded new interventions to reduce the burden of RSV disease.
Defining the immunological goals for respiratory syncytial virus (RSV) vaccination requires understanding of RSV biology and tropism, mechanisms of cell-to-cell spread and immunity, epidemiology, and transmission dynamics. The immunological goals for a particular vaccine would be product-specific based on antigen selection, delivery approach, and target population. There are many ways to achieve immunity against RSV infection involving innate and adaptive responses, humoral, and cellular effector mechanisms, and mucosal and systemic responses. Both protective and pathological immune response patterns have been demonstrated in animal models and humans. In this short commentary, the entire information matrix that may inform the design of particular vaccine candidates cannot be fully reviewed, but the rationale behind the major vaccine approaches in key target populations will be discussed.
SARS-CoV-2 Viral Variants—Tackling a Moving Target Mascola, John R; Graham, Barney S; Fauci, Anthony S
JAMA : the journal of the American Medical Association,
04/2021, Letnik:
325, Številka:
13
Journal Article
Recenzirano
Mascola et al discuss a report by Zhang and colleagues on the emergence of a novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant in Southern California that accounted for 44% ...(37 of 85) of samples collected and studied in January 2021. The terminology of viral variation can be confusing because the media and even scientific communications often use the terms variant, strain, and lineage interchangeably. The terminology reflects the basic replication biology of RNA viruses that results in the introduction of mutations throughout the viral genome. When specific mutations, or sets of mutations, are selected through numerous rounds of viral replication, a new variant can emerge. If the sequence variation produces a virus with distinctly different phenotypic characteristics, the variant is co-termed a strain. When through genetic sequencing and phylogenetic analysis a new variant is detected as a distinct branch on a phylogenetic tree, a new lineage is born.
Two injections of mRNA-1273, a lipid nanoparticle–encapsulated mRNA-based vaccine produced in collaboration with the NIAID that encodes the SARS-CoV-2 spike protein, conferred protection against ...Covid-19 illness in 94% of vaccinated patients. Adverse effects of the vaccine were mild, transient local reactions, and the incidence of systemic effects such as fever, headache, and fatigue was low.
The COVID-19 pandemic has had widespread effects across the globe, and its causative agent, SARS-CoV-2, continues to spread. Effective interventions need to be developed to end this pandemic. Single ...and combination therapies with monoclonal antibodies have received emergency use authorization
, and more treatments are under development
. Furthermore, multiple vaccine constructs have shown promise
, including two that have an approximately 95% protective efficacy against COVID-19
. However, these interventions were directed against the initial SARS-CoV-2 virus that emerged in 2019. The recent detection of SARS-CoV-2 variants B.1.1.7 in the UK
and B.1.351 in South Africa
is of concern because of their purported ease of transmission and extensive mutations in the spike protein. Here we show that B.1.1.7 is refractory to neutralization by most monoclonal antibodies against the N-terminal domain of the spike protein and is relatively resistant to a few monoclonal antibodies against the receptor-binding domain. It is not more resistant to plasma from individuals who have recovered from COVID-19 or sera from individuals who have been vaccinated against SARS-CoV-2. The B.1.351 variant is not only refractory to neutralization by most monoclonal antibodies against the N-terminal domain but also by multiple individual monoclonal antibodies against the receptor-binding motif of the receptor-binding domain, which is mostly due to a mutation causing an E484K substitution. Moreover, compared to wild-type SARS-CoV-2, B.1.351 is markedly more resistant to neutralization by convalescent plasma (9.4-fold) and sera from individuals who have been vaccinated (10.3-12.4-fold). B.1.351 and emergent variants
with similar mutations in the spike protein present new challenges for monoclonal antibody therapies and threaten the protective efficacy of current vaccines.
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