RSV recombinant candidate vaccine G1F/M2 with CpG as an adjuvant prevents vaccine-associated lung inflammation, which may be associated with the appropriate types of immune memory in spleens and lungs

Exacerbated lung inflammation in offspring with high maternal antibody levels following secondary RSV exposure

Respiratory syncytial virus (RSV) is the primary cause of bronchiolitis-related hospitalizations among children under 5 years of age, with reinfection being common throughout life. Maternal vaccination has emerged as a promising strategy, delivering elevated antibody levels to newborns for immediate protection. However, limited research has explored the protective efficacy of maternal antibodies (matAbs) against secondary RSV infections in offspring. To address this gap, we employed a mouse model of maternal RSV vaccination and secondary infection of offspring to evaluate lung pathology following RSV reinfection in mice with varying levels of maternal antibody (matAb). Additionally, we aimed to investigate the potential causes of exacerbated lung inflammation in offspring with high matAb levels following secondary RSV exposure. Our findings revealed that offspring with elevated levels of maternal pre-F antibody demonstrated effective protection against lung pathology following the initial RSV infection. However, this protection was compromised upon reinfection, manifesting as heightened weight loss, exacerbated lung pathology, increased expression of RSV-A N genes, eosinophilia, enhanced IL-5, IL-13, MUC5AC, and eosinophils Major Basic Protein (MBP) production in lung tissue compared to offspring lacking matAbs. Importantly, these unexpected outcomes were not attributed to antibody-dependent enhancement (ADE) resulting from declining matAb levels over time. Notably, our findings showed a decline in secretory IgA (sIgA), mucosal IgA, and mucosal IgG levels in offspring with high matAb levels post-primary RSV challenge. We propose that this decline may be a critical factor contributing to the ineffective protection observed during secondary RSV exposure. Overall, these findings offer valuable insights into maternal vaccination against RSV, contributing to a comprehensive understanding and mitigation of potential risks associated with maternal RSV vaccination.

Assessing the generation of tissue resident memory T cells by vaccines

Vaccines have been a hugely successful public health intervention, virtually eliminating many once common diseases of childhood. However, they have had less success in controlling endemic pathogens including Mycobacterium tuberculosis, herpesviruses and HIV. A focus on vaccine-mediated generation of neutralizing antibodies, which has been a successful approach for some pathogens, has been complicated by the emergence of escape variants, which has been seen for pathogens such as influenza viruses and SARS-CoV-2, as well as for HIV-1. We discuss how vaccination strategies aimed at generating a broad and robust T cell response may offer superior protection against pathogens, particularly those that have been observed to mutate rapidly. In particular, we consider here how a focus on generating resident memory T cells may be uniquely effective for providing immunity to pathogens that typically infect (or become reactivated in) the skin, respiratory mucosa or other barrier tissues.

Immunopathology of RSV: An Updated Review

RSV is a leading cause of respiratory tract disease in infants and the elderly. RSV has limited therapeutic interventions and no FDA-approved vaccine. Gaps in our understanding of virus-host interactions and immunity contribute to the lack of biological countermeasures. This review updates the current understanding of RSV immunity and immunopathology with a focus on interferon responses, animal modeling, and correlates of protection.

Immune response of C57BL/6J mice to herpes zoster subunit vaccines formulated with nanoemulsion-based and liposome-based adjuvants

Herpes zoster (HZ) is a recurrent nerve tissue infection caused by the reactivation of varicella-zoster virus (VZV). At present, two vaccines, the live attenuated vaccine Zostavax™ and AS01B-adjuvanted recombinant subunit vaccine Shingrix™, are commercially available for HZ. The latter is superior to the former in terms of efficacy and duration of immunity in the elderly. In this study, we used glycoprotein E (gE) as an antigen, and investigated the effects of various adjuvants (MF59, MF59/CpG 2006, and MF59/QS-21) on the immune response of C57BL/6J mice to find an alternative adjuvant to AS01B-like adjuvant of liposome/QS-21/MPL. In addition to safety, the gE-specific antibody, IgG antibody subtype, and cytokine secretion by splenocytes, and cell-mediated immune responses were determined using ELISA and ELISPOT assays, respectively. Our results showed no significant effects on the body weight, temperature, or behavior of mice vaccinated with PBS or all adjuvanted vaccines. All adjuvanted vaccine groups showed significantly higher gE-specific IgG antibody levels than the gE-alone group on day 28 after the first vaccine dose. In addition, all adjuvants induced a remarkable increase in both IgG1 and IgG2b levels. However, MF59/QS-21 and MF59/CpG 2006 showed comparable capacities to those of liposome/QS-21/MPL in increasing the IgG2c levels, being superior to MF59. Further investigation revealed that MF59 only induced a limited increase in the levels of Th1 and Th2 cytokines, while MF59/QS-21, MF59/CpG 2006, and liposome/QS-21/MPL led to a significant increase in the secretion of interferon gamma (IFN-γ), IL-2, IL-4, and IL-10 and showed a Th1-biased immune response. Moreover, MF59/QS-21, MF59/CpG 2006, and liposome/QS-21/MPL adjuvanted vaccines resulted in comparable gE-specific IFN-γ + immune cell responses. These results suggest that the combination of MF59 with QS-21 or CpG 2006 may be a promising adjuvant candidate for subunit HZ vaccines. Further investigations are needed to illustrate their durability and efficacy in aged mice.

The impact of immuno-aging on SARS-CoV-2 vaccine development

The SARS-CoV-2 pandemic has almost 56 million confirmed cases resulting in over 1.3 million deaths as of November 2020. This infection has proved more deadly to older adults (those >65 years of age) and those with immunocompromising conditions. The worldwide population aged 65 years and older is increasing, and the total number of aged individuals will outnumber those younger than 65 years by the year 2050. Aging is associated with a decline in immune function and chronic activation of inflammation that contributes to enhanced viral susceptibility and reduced responses to vaccination. Here we briefly review the pathogenicity of the virus, epidemiology and clinical response, and the underlying mechanisms of human aging in improving vaccination. We review current methods to improve vaccination in the older adults using novel vaccine platforms and adjuvant systems. We conclude by summarizing the existing clinical trials for a SARS-CoV-2 vaccine and discussing how to address the unique challenges for vaccine development presented with an aging immune system.

Immunomodulation as a Novel Strategy for Prevention and Treatment of Bordetella spp. Infections

Well-adapted pathogens have evolved to survive the many challenges of a robust immune response. Defending against all host antimicrobials simultaneously would be exceedingly difficult, if not impossible, so many co-evolved organisms utilize immunomodulatory tools to subvert, distract, and/or evade the host immune response. Bordetella spp. present many examples of the diversity of immunomodulators and an exceptional experimental system in which to study them. Recent advances in this experimental system suggest strategies for interventions that tweak immunity to disrupt bacterial immunomodulation, engaging more effective host immunity to better prevent and treat infections. Here we review advances in the understanding of respiratory pathogens, with special focus on Bordetella spp., and prospects for the use of immune-stimulatory interventions in the prevention and treatment of infection.

Contribution of Resident Memory CD8+ T Cells to Protective Immunity Against Respiratory Syncytial Virus and Their Impact on Vaccine Design

Worldwide, human respiratory syncytial virus (RSV) is the most common etiological agent for acute lower respiratory tract infections (ALRI). RSV-ALRI is the major cause of hospital admissions in young children, and it can cause in-hospital deaths in children younger than six months old. Therefore, RSV remains one of the pathogens deemed most important for the generation of a vaccine. On the other hand, the effectiveness of a vaccine depends on the development of immunological memory against the pathogenic agent of interest. This memory is achieved by long-lived memory T cells, based on the establishment of an effective immune response to viral infections when subsequent exposures to the pathogen take place. Memory T cells can be classified into three subsets according to their expression of lymphoid homing receptors: central memory cells (T_CM), effector memory cells (T_EM) and resident memory T cells (T_RM). The latter subset consists of cells that are permanently found in non-lymphoid tissues and are capable of recognizing antigens and mounting an effective immune response at those sites. T_RM cells activate both innate and adaptive immune responses, thus establishing a robust and rapid response characterized by the production of large amounts of effector molecules. T_RM cells can also recognize antigenically unrelated pathogens and trigger an innate-like alarm with the recruitment of other immune cells. It is noteworthy that this rapid and effective immune response induced by T_RM cells make these cells an interesting aim in the design of vaccination strategies in order to establish T_RM cell populations to prevent respiratory infectious diseases. Here, we discuss the biogenesis of T_RM cells, their contribution to the resolution of respiratory viral infections and the induction of T_RM cells, which should be considered for the rational design of new vaccines against RSV.