Repeated Influenza Vaccination Boosts and Maintains H1N1pdm09 Neuraminidase Antibody Titers

COBRA N2 NA vaccines induce protective immune responses against influenza viral infection

Influenza neuraminidase (NA) is a promising target for a broadly protective vaccine. In this study, the Computationally Optimized Broadly Reactive Antigen (COBRA) methodology was used to develop N2 NA vaccine candidates. The unique wild type (WT) N2 sequences of human and swine influenza strains isolated between 1957 and 2019 were used to design the COBRA N2-A NA vaccine, while the unique WT N2 sequences of human influenza strains isolated between 2000 and 2019 were used to design the COBRA N2-B NA vaccine. Sera collected from COBRA N2 NA vaccinated mice showed more broadly reactive antibody responses against a broad panel of H×N2 influenza virus strains than sera collected from mice vaccinated with WT N2 NA vaccines. Antibodies elicited by COBRA or WT N2 NA antigens cross react with recent human H3N2 influenza viruses from different clades, while the antibodies elicited by A/Switzerland/9715293/2013 hemagglutinin (HA) reacted with viruses from the same clade. Furthermore, mice vaccinated with COBRA N2-B NA vaccine had lower viral lung titers compared to mock vaccinated mice when challenged with human H3N2 influenza viruses. Thus, the COBRA N2 NA vaccines elicit broadly protective murine anti-NA antibodies against multiple strains across subtypes and the viral loads were significantly decreased in the lungs of the mice in the COBRA N2 NA vaccine groups, compared to the mice in the mock vaccinated group, indicating that the COBRA-based N2 subtype NA vaccines have a potential to be a component in a universal influenza vaccine.

Vaccine-induced NA immunity decreases viral shedding, but does not disrupt chains of airborne transmission for the 2009 pandemic H1N1 virus in ferrets

Split-virion-inactivated influenza vaccines are formulated based on viral hemagglutinin content. These vaccines also contain the viral neuraminidase (NA) protein, but NA content is not standardized and varies between manufacturers. In clinical studies and animal models, antibodies directed toward NA reduced disease severity and viral load; however, the impact of vaccine-induced NA immunity on airborne transmission of influenza A viruses is not well characterized. Therefore, we evaluated if vaccination against NA could disrupt chains of airborne transmission for the 2009 pandemic H1N1 virus in ferrets. Immunologically naïve donor ferrets were infected with the 2009 pandemic H1N1 virus and then paired in transmission cages with mock- or NA-vaccinated respiratory contacts. The mock- and NA-vaccinated animals were then monitored daily for infection, and once infected, these animals were paired with a naive secondary respiratory contact. In these studies, all mock- and NA-vaccinated animals became infected; however, NA-vaccinated animals shed significantly less virus for fewer days relative to mock-vaccinated animals. For the secondary contacts, 6/6 and 5/6 animals became infected after exposure to mock- and NA-vaccinated animals, respectively. To determine if vaccine-induced immune pressure selected for escape variants, we sequenced viruses recovered from ferrets. No mutations in NA became enriched during transmission. These findings indicate that despite reducing viral load, vaccine-induced NA immunity does not prevent infection during continuous airborne exposure and subsequent onward airborne transmission of the 2009 pandemic H1N1 virus.

IMPORTANCE

In humans and animal models, immunity against neuraminidase (NA) reduces disease severity and viral replication during influenza infection. However, we have a limited understanding of the impact of NA immunity on viral transmission. Using chains of airborne transmission in ferrets as a strategy to simulate a more natural route of infection, we assessed if vaccine-induced NA immunity could disrupt transmission of the 2009 pandemic H1N1 virus. The 2009 pandemic H1N1 virus transmitted efficiently through chains of transmission in the presence of NA immunity, but NA-vaccinated animals shed significantly less virus and had accelerated viral clearance. To determine if immune pressure led to the generation of escape variants, viruses in ferret nasal wash samples were sequenced, and no mutations in NA were identified. These findings demonstrate that vaccine-induced NA immunity is not sufficient to prevent infection via airborne exposure and onward airborne transmission of the 2009 pandemic H1N1 virus.

Pharmacovigilance in Vaccines: Importance, Main Aspects, Perspectives, and Challenges-A Narrative Review

Pharmacovigilance plays a central role in safeguarding public health by continuously monitoring the safety of vaccines, being critical in a climate of vaccine hesitancy, where public trust is paramount. Pharmacovigilance strategies employed to gather information on adverse events following immunization (AEFIs) include pre-registration data, media reports, clinical trials, and societal reporting. Early detection of AEFIs during clinical trials is crucial for thorough safety analysis and preventing serious reactions once vaccines are deployed. This review highlights the importance of societal reporting, encompassing contributions from community members, healthcare workers, and pharmaceutical companies. Technological advancements such as quick response (QR) codes can facilitate prompt AEFI reporting. While vaccines are demonstrably safe, the possibility of adverse events necessitates continuous post-marketing surveillance. However, underreporting remains a challenge, underscoring the critical role of public engagement in pharmacovigilance. This narrative review comprehensively examines and synthesizes key aspects of virus vaccine pharmacovigilance, with special considerations for specific population groups. We explore applicable legislation, the spectrum of AEFIs associated with major vaccines, and the unique challenges and perspectives surrounding pharmacovigilance in this domain.

Development and characterization of an antibody that recognizes influenza virus N1 neuraminidases

Influenza A viruses (IAVs) continue to pose a huge threat to public health, and their prevention and treatment remain major international issues. Neuraminidase (NA) is the second most abundant surface glycoprotein on influenza viruses, and antibodies to NA have been shown to be effective against influenza infection. In this study, we generated a monoclonal antibody (mAb), named FNA1, directed toward N1 NAs. FNA1 reacted with H1N1 and H5N1 NA, but failed to react with the NA proteins of H3N2 and H7N9. In vitro, FNA1 displayed potent antiviral activity that mediated both NA inhibition (NI) and blocking of pseudovirus release. Moreover, residues 219, 254, 358, and 388 in the NA protein were critical for FNA1 binding to H1N1 NA. However, further validation is necessary to confirm whether FNA1 mAb is indeed a good inhibitor against NA for application against H1N1 and H5N1 viruses.

Assessment of Humoral Immune Responses to Repeated Influenza Vaccination in a Multiyear Cohort: A 5-Year Follow-up

The long-term effects of host factors on vaccine-elicited immune responses have not been well studied, and the interactions of host factors with annual influenza vaccinations are yet to be explored. We analyzed data from a cohort of 386 individuals who received the standard-dose influenza vaccine and enrolled in ≥2 seasons from 2016 to 2020. Our analyses indicated disparate vaccine-elicited immune responses between males and females in adults when they were repeatedly vaccinated for at least 2 seasons. Notably, we found interactive effects between age and body mass index (BMI) on overall immune responses, and between sex at birth and BMI in adults.

Anti-neuraminidase immunity in the combat against influenza

INTRODUCTION

Anti-neuraminidase (NA) immunity correlates with the protection against influenza virus infection in both human and animal models. The aim of this review is to better understand the mechanism of anti-NA immunity, and also to evaluate the approaches on developing NA-based influenza vaccines or enhancing immune responses against NA for current influenza vaccines.

AREAS COVERED

In this review, the structure of influenza neuraminidase, the contribution of anti-NA immunity to protection, as well as the efforts and challenges of targeting the immune responses to NA were discussed. We also listed some of the newly discovered anti-NA monoclonal antibodies and discussed their contribution in therapeutic as well as the antigen design of a broadly protective NA vaccine.

EXPERT OPINION

Targeting the immune response to both HA and NA may be critical for achieving the optimal protection since there are different mechanisms of HA and NA elicited protective immunity. Monoclonal antibodies (mAbs) that target the conserved protective lateral face or catalytic sites are effective therapeutics. The epitope discovery using monoclonal antibodies may benefit NA-based vaccine elicited broadly reactive antibody responses. Therefore, the potential for a vaccine that elicits cross-reactive antibodies against neuraminidase is a high priority for next-generation influenza vaccines.

B-Cell Responses to Sars-Cov-2 mRNA Vaccines

Most vaccines against viral pathogens protect through the acquisition of immunological memory from long-lived plasma cells that produce antibodies and memory B cells that can rapidly respond upon an encounter with the pathogen or its variants. The COVID-19 pandemic and rapid deployment of effective vaccines have provided an unprecedented opportunity to study the immune response to a new yet rapidly evolving pathogen. Here we review the scientific literature and our efforts to understand antibody and B-cell responses to SARS-CoV-2 vaccines, the effect of SARSCoV-2 infection on both primary and secondary immune responses, and how repeated exposures may impact outcomes.

SARS-CoV-2 vaccination induces mucosal antibody responses in previously infected individuals

Immune responses at the respiratory mucosal interface are critical to prevent respiratory infections but it is unclear to what extent antigen specific mucosal secretory IgA (SIgA) antibodies are induced by mRNA vaccination in humans. Here we analyze paired serum and saliva samples from patients with and without prior coronavirus disease 2019 (COVID-19) at multiple time points pre and post severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA vaccination. Our results suggest mucosal SIgA responses induced by mRNA vaccination are impacted by pre-existing immunity. Indeed, vaccination induced a minimal mucosal SIgA response in individuals without pre-exposure to SARS-CoV-2 while SIgA induction after vaccination was more efficient in patients with a history of COVID-19.

Discovery and pharmacodynamic evaluation of the novel butene lactone derivative M355 against influenza A virus in vitro and in vivo

A new series of butene lactone derivatives were designed according to an influenza neuraminidase target and their antiviral activities against H1N1 infection of MDCK cells were evaluated. Among them, a compound that was given the name M355 was identified as the most potent against H1N1 (EC₅₀ = 14.7 μM) with low toxicity (CC₅₀ = 538.13 μM). It also visibly reduced the virus-induced cytopathic effect. Time-of-addition analysis indicated that H1N1 was mostly suppressed by M355 at the late stage of its infectious cycle. M355 inhibited neuraminidase in a dose-dependent fashion to a similar extent as oseltamivir, which was also indicated by computer modeling experiment. In a mouse model, lung lesions and virus load were reduced and the expression of nucleoprotein was moderated by M355. The ELISA and qRT-PCR analyses revealed that the levels of IFN-γ, IRF-3, TLR-3, TNF-α, IL-1β, IL-6 and IL-8 were down-regulated in the M355-treated groups, whereas the levels of IL-10 and IL-13 were up-regulated. Similarly, IgG was found to be increased in infected mice plasma. These results demonstrate that M355 inhibit the expression of H1N1 in both cellular and animal models. Thus, M355 has the potential to be effective in the treatment of influenza A virus infection. This article is protected by copyright. All rights reserved.