Harnessing Cellular Immunity for Vaccination against Respiratory Viruses

Efficacy of budesonide/formoterol inhalation powder in treating viral pneumonia in children

BACKGROUND

Respiratory viruses are increasingly detected in children with community-acquired pneumonia. Further strategies to limit antibiotic use in children with viral pneumonia are warranted.

AIM

To explore clinical efficacy of budesonide/formoterol inhalation powder for viral pneumonia in children and its impact on cellular immunity and inflammatory factor production.

METHODS

A total of 60 children with viral pneumonia were recruited: 30 receiving budesonide/formoterol inhalation powder and 30 conventional symptomatic treatment. Outcome measures included peripheral blood levels of inflammatory cytokines, CD4⁺, CD8⁺, Th1, Th2, Th17 and Treg, clinical efficacy, and incidence of adverse reactions.

RESULTS

Compared with the control group, the observation group showed a significant reduction in interleukin-6 and high-sensitivity C-reactive protein levels after treatment. Compared with the control group, the observation group showed a significant increase in CD4⁺/CD8⁺ and Th1/Th2 levels, and a decrease in Th17/Treg levels after treatment. The total effective rates in the observation group and the control group were 93.75% and 85.00%, respectively, which was a significant difference (P = 0.003).

CONCLUSION

Budesonide/formoterol inhalation powder significantly improved therapeutic efficacy for viral pneumonia in children. The mechanism of action may be related to downregulation of the inflammatory response and improved cellular immune function.

Flagellin-Fused Protein Targeting M2e and HA2 Induces Innate and T-Cell Responses in Mice of Different Genetic Lines

Efficient control of influenza A infection can potentially be achieved through the development of broad-spectrum vaccines. Recombinant proteins incorporating conserved influenza A virus peptides are one of the platforms for the development of cross-protective influenza vaccines. We constructed a recombinant protein Flg-HA2-2-4M2ehs, in which the extracellular domain of the M2 protein (M2e) and the sequence (aa76-130) of the second subunit of HA (HA2) were used as target antigens. In this study, we investigated the ability of the Flg-HA2-2-4M2ehs protein to activate innate immunity and stimulate the formation of T-cell response in mice of different genetic lines after intranasal immunization. Our studies showed that the Flg-HA2-2-4M2ehs protein was manifested in an increase in the relative content of neutrophils, monocytes, and interstitial macrophages, against the backdrop of a decrease in the level of dendritic cells and increased expression in the CD86 marker. In the lungs of BALB/c mice, immunization with the Flg-HA2-2-4M2ehs protein induced the formation of antigen-specific CD4+ and CD8+ effector memory T cells, producing TNF-α. In mice C57Bl/6, the formation of antigen-specific effector CD8+ T cells, predominantly producing IFN-γ+, was demonstrated. The data obtained showed the formation of CD8+ and CD4+ effector memory T cells expressing the CD107a.

A Review of Different Vaccines and Strategies to Combat COVID-19

In December 2019, an unknown viral infection emerged and quickly spread worldwide, resulting in a global pandemic. This novel virus caused severe pneumonia and acute respiratory distress syndrome caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). It has caused 6.25 millions of deaths worldwide and remains a major concern for health, society, and the economy. As vaccination is one of the most efficient ways to combat this pandemic, different vaccines were developed in a short period. This review article discusses how coronavirus affected the top nations of the world and the vaccines being used for the prevention. Amongst the vaccines, some vaccines have already been approved, and some have been involved in clinical studies. The article also provides insight into different COVID-19 vaccine platforms, their preparation, working, efficacy, and side effects.

Will Host Genetics Affect the Response to SARS-CoV-2 Vaccines? Historical Precedents

Recent progress in genomics and bioinformatics technologies have allowed for the emergence of immunogenomics field. This intersection of immunology and genetics has broadened our understanding of how the immune system responds to infection and vaccination. While the immunogenetic basis of the huge clinical variability in response to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is currently being extensively studied, the host genetic determinants of SARS-CoV-2 vaccines remain largely unknown. Previous reports evidenced that vaccines may not protect all populations or individuals equally, due to multiple host- and vaccine-specific factors. Several studies on vaccine response to measles, rubella, hepatitis B, smallpox, and influenza highlighted the contribution of genetic mutations or polymorphisms in modulating the innate and adaptive immunity following vaccination. Specifically, genetic variants in genes encoding virus receptors, antigen presentation, cytokine production, or related to immune cells activation and differentiation could influence how an individual responds to vaccination. Although such knowledge could be utilized to generate personalized vaccine strategies to optimize the vaccine response, studies in this filed are still scarce. Here, we briefly summarize the scientific literature related to the immunogenetic determinants of vaccine-induced immunity, highlighting the possible role of host genetics in response to SARS-CoV-2 vaccines as well.

Functional Severe Acute Respiratory Syndrome Coronavirus 2 Virus-Like Particles From Insect Cells

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remains a major epidemic threat since the beginning of 2020. Efforts to combat the virus and the associated coronavirus disease 2019 (COVID-19) disease are being undertaken worldwide. To facilitate the research on the virus itself, a number of surrogate systems have been developed. Here, we report the efficient production of SARS-CoV-2 virus-like particles (VLPs) in insect cells. Contrary to widely used pseudovirus particles, where only one coronaviral protein is displayed within a heterologous scaffold, developed VLPs are structurally similar to the native virus and allow for more throughput studies on the biology of the infection. On the other hand, being devoid of the viral genome, VLPs are unable to replicate and thus safe to work with. Importantly, this is the first report showing that SARS-CoV-2 VLPs can be efficiently produced in insect cells and purified using scalable affinity chromatography.

Novel Vaccine Adjuvants as Key Tools for Improving Pandemic Preparedness

Future infectious disease outbreaks are inevitable; therefore, it is critical that we maximize our readiness for these events by preparing effective public health policies and healthcare innovations. Although we do not know the nature of future pathogens, antigen-agnostic platforms have the potential to be broadly useful in the rapid response to an emerging infection-particularly in the case of vaccines. During the current COVID-19 pandemic, recent advances in mRNA engineering have proven paramount in the rapid design and production of effective vaccines. Comparatively, however, the development of new adjuvants capable of enhancing vaccine efficacy has been lagging. Despite massive improvements in our understanding of immunology, fewer than ten adjuvants have been approved for human use in the century since the discovery of the first adjuvant. Modern adjuvants can improve vaccines against future pathogens by reducing cost, improving antigen immunogenicity, and increasing antigen stability. In this perspective, we survey the current state of adjuvant use, highlight potentially impactful preclinical adjuvants, and propose new measures to accelerate adjuvant safety testing and technology sharing to enable the use of "off-the-shelf" adjuvant platforms for rapid vaccine testing and deployment in the face of future pandemics.

Rapid, robust, and sustainable antibody responses to mRNA COVID-19 vaccine in convalescent COVID-19 individuals

Longitudinal studies are needed to evaluate the SARS-CoV-2 mRNA vaccine antibody response under real-world conditions. This longitudinal study investigated the quantity and quality of SARS-CoV-2 antibody response in 846 specimens from 350 patients, comparing BNT162b2-vaccinated individuals (19 previously diagnosed with COVID-19, termed RecoVax; and 49 never diagnosed, termed NaiveVax) with 122 hospitalized unvaccinated (HospNoVax) and 160 outpatient unvaccinated (OutPtNoVax) COVID-19 patients. NaiveVax experienced delay in generating SARS-CoV-2 total antibodies (TAb) and surrogate neutralizing antibodies (SNAb) after the first vaccine dose (D1) but rapid increase in antibody levels after the second dose (D2). However, these never reached RecoVax's robust levels. In fact, NaiveVax TAb and SNAb levels decreased 4 weeks after D2. For the most part, RecoVax TAb persisted, after reaching maximal levels 2 weeks after D2, but SNAb decreased significantly about 6 months after D1. Although NaiveVax avidity lagged behind that of RecoVax for most of the follow-up periods, NaiveVax did reach similar avidity by about 6 months after D1. These data suggest that 1 vaccine dose elicits maximal antibody response in RecoVax and may be sufficient. Also, despite decreasing levels in TAb and SNAb over time, long-term avidity may be a measure worth evaluating and possibly correlating to vaccine efficacy.

Protective humoral and cellular immune responses to SARS-CoV-2 persist up to 1 year after recovery

SARS-CoV-2 vaccination has been launched worldwide to build effective population-level immunity to curb the spread of this virus. The effectiveness and duration of protective immunity is a critical factor for public health. Here, we report the kinetics of the SARS-CoV-2 specific immune response in 204 individuals up to 1-year after recovery from COVID-19. RBD-IgG and full-length spike-IgG concentrations and serum neutralizing capacity decreases during the first 6-months, but is maintained stably up to 1-year after hospital discharge. Even individuals who had generated high IgG levels during early convalescent stages had IgG levels that had decreased to a similar level one year later. Notably, the RBD-IgG level positively correlates with serum neutralizing capacity, suggesting the representative role of RBD-IgG in predicting serum protection. Moreover, viral-specific cellular immune protection, including spike and nucleoprotein specific, persisted between 6 months and 12 months. Altogether, our study supports the persistence of viral-specific protective immunity over 1 year.

Intervention Strategies for Seasonal and Emerging Respiratory Viruses with Drugs and Vaccines Targeting Viral Surface Glycoproteins

Vaccines and therapeutics targeting viral surface glycoproteins are a major component of disease prevention for respiratory viral diseases. Over the years, vaccines have proven to be the most successful intervention for preventing disease. Technological advances in vaccine platforms that focus on viral surface glycoproteins have provided solutions for current and emerging pathogens like SARS-CoV-2, and our understanding of the structural basis for antibody neutralization is guiding the selection of other vaccine targets for respiratory viruses like RSV. This review discusses the role of viral surface glycoproteins in disease intervention approaches.

INFECTION-ACQUIRED VERSUS VACCINE-INDUCED IMMUNITY AGAINST COVID-19

The course of COVID-19 depends on a dynamic interplay between SARS-CoV-2 and the host's immune system. Although it is an emerging global health issue, little is known about the specificity, safety, and duration of the immunity elicited by the virus. This hypothesis article explores the benefits of infection-acquired and vaccine-induced immunity against COVID-19, suggesting that the latter outweighs the former. Comparative studies are proposed to explain and reveal all aspects of the immune responses. Although vaccine development relies on studies of naturally acquired immune responses, there are still no comparative analyses of the natural and vaccine immunity against SARS-CoV-2. Moreover, there are scarce reports on the characteristics of both types of responses. The scientific facts about the virulence of SARS-CoV-2 affecting the immune system are of great importance for proposed comparative analyses. Various immunological methods can be employed to elucidate infection-acquired and vaccine-induced immunity against SARS-CoV-2. The safe vaccination of subjects with and without COVID-19 history may disrupt the virus spreading and end the pandemic.

Eosinophils and COVID-19: diagnosis, prognosis, and vaccination strategies

The unprecedented impact of the coronavirus disease 2019 (COVID-19) pandemic has resulted in global challenges to our health-care systems and our economic security. As such, there has been significant research into all aspects of the disease, including diagnostic biomarkers, associated risk factors, and strategies that might be used for its treatment and prevention. Toward this end, eosinopenia has been identified as one of many factors that might facilitate the diagnosis and prognosis of severe COVID-19. However, this finding is neither definitive nor pathognomonic for COVID-19. While eosinophil-associated conditions have been misdiagnosed as COVID-19 and others are among its reported complications, patients with pre-existing eosinophil-associated disorders (e.g., asthma, eosinophilic gastrointestinal disorders) do not appear to be at increased risk for severe disease; interestingly, several recent studies suggest that a diagnosis of asthma may be associated with some degree of protection. Finally, although vaccine-associated aberrant inflammatory responses, including eosinophil accumulation in the respiratory tract, were observed in preclinical immunization studies targeting the related SARS-CoV and MERS-CoV pathogens, no similar complications have been reported clinically in response to the widespread dissemination of either of the two encapsulated mRNA-based vaccines for COVID-19.