Current influenza virus vaccines are annually reformulated to elicit protection by generating an immune response toward the virus strains that are predicted to circulate in the upcoming influenza ...season. These vaccines provide limited protection in cases of antigenic mismatch, when the vaccine and the circulating viral strains differ. The emergence of unexpected pandemic viruses presents an additional challenge to vaccine production. To increase influenza virus preparedness, much work has been dedicated to the development of a universal vaccine. Focusing on regions of viral proteins that are highly conserved across virus subtypes, vaccine strategies involving the matrix 2 protein, stalk domain of the hemagglutinin, and multivalent approaches have provided broad-based protection in animal models and show much promise. This review summarizes the most encouraging advances in the field with a focus on novel vaccine designs that have yielded promising preclinical and clinical data.
► Respiratory viruses are spread from person to person via various modes of transmission, including direct and indirect contact, droplet spray, and aerosol. ► Virus transmission is affected by a ...number of factors, including environmental determinants, host behavior, host defense mechanisms, and virus infectivity. ► Uncertainties remain with respect to the relative importance of these factors and the roles that they play.
Many viruses are capable of infecting the human respiratory tract to cause disease. These viruses display various transmission patterns among humans; however, they all share the ability to transmit from person to person, and their human transmissibility is influenced by the environment in which pathogen and host meet. This review aims to summarize recent and significant observations regarding the impact of environmental factors such as weather and climate, humidity, temperature, and airflow on the transmission of human respiratory viruses. Where possible, knowledge gaps that require further scientific study will be identified.
Rare diseases affect as many as 60 million people in the United States and Europe. However, most rare diseases lack effective therapies and are in critical need of clinical research. Our objective ...was to determine the frequency of noncompletion and nonpublication of trials studying rare diseases.
We conducted a cross-sectional analysis of randomized clinical trials studying rare diseases as defined by the Genetic and Rare Disease Information Center database that were registered in ClinicalTrials.gov between January 1, 2010, and December 31, 2012, and completed or discontinued by December 31, 2014. Our main outcome measures were the frequency of trial noncompletion and, among completed studies, frequency of trial nonpublication at 2 and 4 years following trial completion. Reasons for discontinuation were extracted from the registry, and trial sponsors were contacted for additional information, as needed. Two independent investigators performed publication searches for each trial in PubMed, EMBASE, and GoogleScholar, allowing for a minimum of 45 months between trial completion and publication. When a publication could not be identified, trial sponsors were contacted to confirm publication status. The impact of funding source on trial noncompletion was assessed with multivariable logistic regression, and the effect on time to publication was examined with Cox proportional hazards regression. Control variables included intervention type, trial phase, masking, enrollment, and study population. We analyzed 659 rare disease trials accounting for 70,305 enrolled patients. Industry was the primary funder for 327 trials (49.6%) and academic institutions for 184 trials (27.9%). There were 79 trials (12.0%) focused on pediatric populations. A total of 199 trials (30.2%) were discontinued. Lack of patient accrual (n = 64, 32.1%) and informative termination (n = 41, 20.6%) were the most common reasons for trial noncompletion. Among completed trials, 306 (66.5%) remained unpublished at 2 years and 142 (31.5%) at 4 years. In multivariable analyses, industry-funded trials were less likely to be discontinued than trials funded by healthcare centers (odds ratio OR 2.42; 95% confidence interval CI 1.34-4.39, P = 0.003). We found no significant association between funding source and time to publication. A total of 18,148 patients were enrolled in trials that were discontinued or unpublished 4 years after completion. A potential limitation of our study is that certain interventional trials for rare diseases may not have been registered in ClinicalTrials.gov, in particular Phase 0 and Phase I trials, which are not required to be registered.
In this study, over half of clinical trials initiated for rare diseases were either discontinued or not published 4 years after completion, resulting in large numbers of patients with rare diseases exposed to interventions that did not lead to informative findings. Concerted efforts are needed to ensure that participation of patients in rare disease trials advances scientific knowledge and treatments for rare diseases.
The influenza virus hemagglutinin molecule possesses a globular head domain that mediates receptor binding and a stalk domain at the membrane-proximal region. We generated functional influenza ...viruses expressing chimeric hemagglutinins encompassing a variety of globular head and stalk combinations, not only from different hemagglutinin subtypes but also from different hemagglutinin phylogenetic groups. These chimeric recombinant viruses possess growth properties similar to those of wild-type influenza viruses and can be used as reagents to measure domain-specific antibodies in virological and immunological assays.
Current influenza virus vaccines protect mostly against homologous virus strains; thus, regular immunization with updated vaccine formulations is necessary to guard against the virus’ hallmark ...remodeling of regions that mediate neutralization. Development of a broadly protective influenza vaccine would mark a significant advance in human infectious diseases research. Antibodies with broad neutralizing activity (nAbs) against multiple influenza virus strains or subtypes have been reported to bind the stalk of the viral hemagglutinin, suggesting that a vaccine based on this region could elicit a broadly protective immune response. Here we describe a hemagglutinin subunit 2 protein (HA2)-based synthetic peptide vaccine that provides protection in mice against influenza viruses of the structurally divergent subtypes H3N2, H1N1, and H5N1. The immunogen is based on the binding site of the recently described nAb 12D1, which neutralizes H3 subtype viruses, demonstrates protective activity in vivo, and, in contrast to a majority of described nAbs, appears to bind to residues within a single α-helical portion of the HA2 protein. Our data further demonstrate that the specific design of our immunogen is integral in the induction of broadly active anti-hemagglutinin antibodies. These results provide proof of concept for an HA2-based influenza vaccine that could diminish the threat of pandemic influenza disease and generally reduce the significance of influenza viruses as human pathogens.
Recently, a new class of broadly neutralizing anti-influenza virus antibodies that target the stalk domain of the viral hemagglutinin was discovered. As such, induction, isolation, characterization, ...and quantification of these novel antibodies has become an area of intense research and great interest. Since most of these antibodies bind to conformational epitopes, the structural integrity of hemagglutinin substrates for the detection and quantification of these antibodies is of high importance. Here we evaluate the binding of these antibodies to soluble, secreted hemagglutinins with or without a carboxy-terminal trimerization domain based on the natural trimerization domain of T4 phage fibritin. The lack of such a domain completely abolishes binding to group 1 hemagglutinins and also affects binding to group 2 hemagglutinins. Additionally, the presence of a trimerization domain positively influences soluble hemagglutinin stability during expression and purification. Our findings suggest that a carboxy-terminal trimerization domain is a necessary requirement for the structural integrity of stalk epitopes on recombinant soluble influenza virus hemagglutinin.
After the emergence of pandemic influenza viruses in 1957, 1968, and 2009, existing seasonal viruses were observed to be replaced in the human population by the novel pandemic strains. We have ...previously hypothesized that the replacement of seasonal strains was mediated, in part, by a population-scale boost in antibodies specific for conserved regions of the hemagglutinin stalk and the viral neuraminidase. Numerous recent studies have shown the role of stalk-specific antibodies in neutralization of influenza viruses; the finding that stalk antibodies can effectively neutralize virus alters the existing dogma that influenza virus neutralization is mediated solely by antibodies that react with the globular head of the viral hemagglutinin. The present study explores the possibility that stalk-specific antibodies were boosted by infection with the 2009 H1N1 pandemic virus and that those antibodies could have contributed to the disappearance of existing seasonal H1N1 influenza virus strains. To study stalk-specific antibodies, we have developed chimeric hemagglutinin constructs that enable the measurement of antibodies that bind the hemagglutinin protein and neutralize virus but do not have hemagglutination inhibition activity. Using these chimeric hemagglutinin reagents, we show that infection with the 2009 pandemic H1N1 virus elicited a boost in titer of virus-neutralizing antibodies directed against the hemagglutinin stalk. In addition, we describe assays that can be used to measure influenza virus-neutralizing antibodies that are not detected in the traditional hemagglutination inhibition assay.
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