Development of a respiratory syncytial virus vaccine using human hepatitis B core-based virus-like particles to induce mucosal immunity

A Chimeric Virus-Like Particle Vaccine Presenting an Immunodominant Epitope of gB Elicited Potent Neutralizing Antibodies against EBV Infection In Vitro and In Vivo

Epstein-Barr Virus (EBV) as the first characterized tumorigenic virus in humans causes heavy disease burdens. An effective vaccine is urgently needed to block EBV infection. Glycoprotein B (gB) is the essential fusogen for EBV infection of all susceptible cell types. We previously demonstrated that neutralizing antibody 3A3 targeting gB effectively blocked EBV infection in a humanized mouse model, indicating that the epitope recognized by 3A3 is the potential immunogen candidate. Hence, we rationally designed a chimeric virus-like particle (cVLP) vaccine based on the hepatitis B core antigen (HBc149) to display gB peptide, αB, recognized by 3A3 (149-αB cVLP). The engineered 149-αB cVLP vaccine self-assembled into spherical particles presenting multiple copies of αB peptide. The 149-αB cVLP vaccine induced much higher antibody titers against αB peptides than gB protein immunization. Importantly, sera antibodies elicited by the 149-αB cVLP vaccine more efficiently blocked EBV infection and membrane fusion of epithelial cells and B cells. Sera from 149-αB cVLP vaccine-immunized rabbits conferred 100% protection against EBV infection in a humanized mouse model. We demonstrated that the 149-αB cVLP vaccine induced potent antigen-specific protective immune responses and shed light on the research of peptide-based vaccines against EBV infection.

Ally, adversary, or arbitrator? The context-dependent role of eosinophils in vaccination for respiratory viruses and subsequent breakthrough infections

Eosinophils are a critical type of immune cell and central players in type 2 immunity. Existing literature suggests that eosinophils also can play a role in host antiviral responses, typically type 1 immune events, against multiple respiratory viruses, both directly through release of antiviral mediators and indirectly through activation of other effector cell types. One way to prime host immune responses toward effective antiviral responses is through vaccination, where typically a type 1-skewed immunity is desirable in the context of intracellular pathogens like respiratory viruses. In the realm of breakthrough respiratory viral infection in vaccinated hosts, an event in which virus can still establish productive infection despite preexisting immunity, eosinophils are most prominently known for their link to vaccine-associated enhanced respiratory disease upon natural respiratory syncytial virus infection. This was observed in a pediatric cohort during the 1960s following vaccination with formalin-inactivated respiratory syncytial virus. More recent research has unveiled additional roles of the eosinophil in respiratory viral infection and breakthrough infection. The specific contribution of eosinophils to the quality of vaccine responses, vaccine efficacy, and antiviral responses to infection in vaccinated hosts remains largely unexplored, especially regarding their potential roles in protection. On the basis of current findings, we will speculate upon the suggested function of eosinophils and consider the many potential ways by which eosinophils may exert protective and pathological effects in breakthrough infections. We will also discuss how to balance vaccine efficacy with eosinophil-related risks, as well as the use of eosinophils and their products as potential biomarkers of vaccine efficacy or adverse events.

From animal studies into clinical trials: the relevance of animal models to develop vaccines and therapies to reduce disease severity and prevent hRSV infection

INTRODUCTION

Human respiratory syncytial virus (hRSV) is an important cause of lower respiratory tract infections in the pediatric and the geriatric population worldwide. There is a substantial economic burden resulting from hRSV disease during winter. Although no vaccines have been approved for human use, prophylactic therapies are available for high-risk populations. Choosing the proper animal models to evaluate different vaccine prototypes or pharmacological treatments is essential for developing efficient therapies against hRSV.

AREAS COVERED

This article describes the relevance of using different animal models to evaluate the effect of antiviral drugs, pharmacological molecules, vaccine prototypes, and antibodies in the protection against hRSV. The animal models covered are rodents, mustelids, bovines, and nonhuman primates. Animals included were chosen based on the available literature and their role in the development of the drugs discussed in this manuscript.

EXPERT OPINION

Choosing the correct animal model is critical for exploring and testing treatments that could decrease the impact of hRSV in high-risk populations. Mice will continue to be the most used preclinical model to evaluate this. However, researchers must also explore the use of other models such as nonhuman primates, as they are more similar to humans, prior to escalating into clinical trials.