Anti-Factor H Antibody Reactivity in Young Adults Vaccinated with a Meningococcal Serogroup B Vaccine Containing Factor H Binding Protein

Hijacking Factor H for Complement Immune Evasion

The complement system is an essential player in innate and adaptive immunity. It consists of three pathways (alternative, classical, and lectin) that initiate either spontaneously (alternative) or in response to danger (all pathways). Complement leads to numerous outcomes detrimental to invaders, including direct killing by formation of the pore-forming membrane attack complex, recruitment of immune cells to sites of invasion, facilitation of phagocytosis, and enhancement of cellular immune responses. Pathogens must overcome the complement system to survive in the host. A common strategy used by pathogens to evade complement is hijacking host complement regulators. Complement regulators prevent attack of host cells and include a collection of membrane-bound and fluid phase proteins. Factor H (FH), a fluid phase complement regulatory protein, controls the alternative pathway (AP) both in the fluid phase of the human body and on cell surfaces. In order to prevent complement activation and amplification on host cells and tissues, FH recognizes host cell-specific polyanionic markers in combination with complement C3 fragments. FH suppresses AP complement-mediated attack by accelerating decay of convertases and by helping to inactivate C3 fragments on host cells. Pathogens, most of which do not have polyanionic markers, are not recognized by FH. Numerous pathogens, including certain bacteria, viruses, protozoa, helminths, and fungi, can recruit FH to protect themselves against host-mediated complement attack, using either specific receptors and/or molecular mimicry to appear more like a host cell. This review will explore pathogen complement evasion mechanisms involving FH recruitment with an emphasis on: (a) characterizing the structural properties and expression patterns of pathogen FH binding proteins, as well as other strategies used by pathogens to capture FH; (b) classifying domains of FH important in pathogen interaction; and (c) discussing existing and potential treatment strategies that target FH interactions with pathogens. Overall, many pathogens use FH to avoid complement attack and appreciating the commonalities across these diverse microorganisms deepens the understanding of complement in microbiology.

Biomimetic bacterial and viral-based nanovesicles for drug delivery, theranostics, and vaccine applications

Smart nanocarriers obtained from bacteria and viruses offer excellent biomimetic properties which has led to significant research into the creation of advanced biomimetic materials. Their versatile biomimicry has application as biosensors, biomedical scaffolds, immobilization, diagnostics, and targeted or personalized treatments. The inherent natural traits of biomimetic and bioinspired bacteria- and virus-derived nanovesicles show potential for their use in clinical vaccines and novel therapeutic drug delivery systems. The past few decades have seen significant progress in the bioengineering of bacteria and viruses to manipulate and enhance their therapeutic benefits. From a pharmaceutical perspective, biomimetics enable the safe integration of naturally occurring bacteria and virus particles to achieve high, stable rates of cellular transfection/infection and prolonged circulation times. In addition, biomimetic technologies can overcome safety concerns associated with live-attenuated and inactivated whole bacteria or viruses. In this review, we provide an update on the utilization of bacterial and viral particles as drug delivery systems, theranostic carriers, and vaccine/immunomodulation modalities.

Safety Surveillance of Bivalent Meningococcal Group B Vaccine, Vaccine Adverse Event Reporting System, 2014-2018

BACKGROUND

In October 2014, MenB-FHbp (Trumenba, Pfizer) became the first meningococcal group B vaccine licensed in the United States. It is approved for use in individuals aged 10-25 years. Our objective was to evaluate the safety of MenB-FHbp postlicensure.

METHODS

The Vaccine Adverse Event Reporting System (VAERS) is a national passive vaccine safety surveillance system. We analyzed US VAERS reports for MenB-FHbp received from the date of licensure in October 2014 through December 2018. We described the characteristics of the persons and adverse events (AEs) reported and calculated reporting rates using the number of doses distributed. We used empirical Bayesian data mining to identify AEs reported at least twice as often as expected compared with all other vaccines.

RESULTS

VAERS received 2106 reports involving MenB-FHbp, representing 698 reports per million doses distributed. The median age of vaccinees was 17 years, and 55% were female. MenB-FHbp was given simultaneously with other vaccines in 37% of reports. Most reports (57%) described AEs that started on the day of or day after vaccination. The most common AEs reported were pyrexia (27%), headache (25%), and pain (16%). There were 44 serious reports (2% of all reports), among which 42 reported a hospitalization. Data mining identified disproportional reporting of headache, pyrexia, chills, and myalgia.

CONCLUSIONS

The AEs most commonly or disproportionately reported following MenB-FHbp were consistent with those identified in clinical trials as described in the US package insert. We did not identify any new safety issues.

Meningococcal Vaccination: Recommendations of the Advisory Committee on Immunization Practices, United States, 2020

This report compiles and summarizes all recommendations from CDC's Advisory Committee on Immunization Practices (ACIP) for use of meningococcal vaccines in the United States. As a comprehensive summary and update of previously published recommendations, it replaces all previously published reports and policy notes. This report also contains new recommendations for administration of booster doses of serogroup B meningococcal (MenB) vaccine for persons at increased risk for serogroup B meningococcal disease. These guidelines will be updated as needed on the basis of availability of new data or licensure of new meningococcal vaccines. ACIP recommends routine vaccination with a quadrivalent meningococcal conjugate vaccine (MenACWY) for adolescents aged 11 or 12 years, with a booster dose at age 16 years. ACIP also recommends routine vaccination with MenACWY for persons aged ≥2 months at increased risk for meningococcal disease caused by serogroups A, C, W, or Y, including persons who have persistent complement component deficiencies; persons receiving a complement inhibitor (e.g., eculizumab [Soliris] or ravulizumab [Ultomiris]); persons who have anatomic or functional asplenia; persons with human immunodeficiency virus infection; microbiologists routinely exposed to isolates of Neisseria meningitidis; persons identified to be at increased risk because of a meningococcal disease outbreak caused by serogroups A, C, W, or Y; persons who travel to or live in areas in which meningococcal disease is hyperendemic or epidemic; unvaccinated or incompletely vaccinated first-year college students living in residence halls; and military recruits. ACIP recommends MenACWY booster doses for previously vaccinated persons who become or remain at increased risk.In addition, ACIP recommends routine use of MenB vaccine series among persons aged ≥10 years who are at increased risk for serogroup B meningococcal disease, including persons who have persistent complement component deficiencies; persons receiving a complement inhibitor; persons who have anatomic or functional asplenia; microbiologists who are routinely exposed to isolates of N. meningitidis; and persons identified to be at increased risk because of a meningococcal disease outbreak caused by serogroup B. ACIP recommends MenB booster doses for previously vaccinated persons who become or remain at increased risk. In addition, ACIP recommends a MenB series for adolescents and young adults aged 16-23 years on the basis of shared clinical decision-making to provide short-term protection against disease caused by most strains of serogroup B N. meningitidis.

Meningococcal factor H binding protein as immune evasion factor and vaccine antigen

Factor H binding protein (fHbp) is a key virulence factor of Neisseria meningitidis and a main component of the two licensed vaccines against serogroup B meningococcus (Bexsero and Trumenba). fHbp is a surface-exposed lipoprotein that enables the bacterium to survive in human blood by binding the human complement regulator factor H (fH). When used as vaccine, the protein induces antibodies with potent bactericidal activity. While the fHbp gene is present in the majority of N. meningitidis serogroup B isolates, the expression level varies up to 15 times between different strains and more than 700 different sequence variants have been described. Antigenically, the protein has been divided into three variants or two subfamilies. The 3D structure of fHbp alone, in combination with fH or in complex with bactericidal antibodies, has been key to understanding the molecular details of the protein. In this article, we will review the biochemical and immunological properties of fHbp, and its key role in meningococcal pathogenesis, complement regulation, and immune evasion.

The Factor H-Binding Site of CspZ as a Protective Target against Multistrain, Tick-Transmitted Lyme Disease

The spirochete Borrelia burgdorferi sensu lato is the causative agent of Lyme disease (LD). The spirochetes produce the CspZ protein that binds to a complement regulator, factor H (FH). Such binding downregulates activation of host complement to facilitate spirochete evasion of complement killing. However, vaccination with CspZ does not protect against LD infection. In this study, we demonstrated that immunization with CspZ-YA, a CspZ mutant protein with no FH-binding activity, protected mice from infection by several spirochete genotypes introduced via tick feeding. We found that the sera from CspZ-YA-vaccinated mice more efficiently eliminated spirochetes and blocked CspZ FH-binding activity than sera from CspZ-immunized mice. We also found that vaccination with CspZ, but not CspZ-YA, triggered the production of anti-FH antibodies, justifying CspZ-YA as an LD vaccine candidate. The mechanistic and efficacy information derived from this study provides insights into the development of a CspZ-based LD vaccine.

Chimeric hepatitis B virus core particles displaying Neisserial surface protein A confer protection against virulent Neisseria meningitidis serogroup B in BALB/c mice

Purpose

The primary goal of the present study was to explore and evaluate the highly conserved Neisserial surface protein A (NspA) molecule, fused with truncated HBV virus-like particles (VLPs), as a candidate vaccine against the virulent Neisseria meningitidis serogroup B (NMB).

Methods

NspA was inserted into the major immunodominant region of the truncated hepatitis B virus core protein (HBc; amino acids 1–144). The chimeric protein, HBc-N144-NspA, was expressed from a prokaryotic vector and generated HBc-like particles, as determined by transmission electron microscopy. Further, the chimeric protein and control proteins were used to immunize mice and the resulting immune responses evaluated by flow cytometry, enzyme-linked immunosorbent assay, and analysis of serum bactericidal activity (SBA) titer.

Results

Evaluation of the immunogenicity of the recombinant HBc-N144-NspA protein showed that it elicited the production of high levels of NspA-specific total IgG. The SBA titer of HBc-N144-NspA/F reached 1:16 2 weeks after the last immunization in BALB/c mice, when human serum complement was included in the vaccine. Immunization of HBc-N144-NspA, even without adjuvant, induced high levels of IL-4 and a high IgG1 to IgG2a ratio, confirming induction of an intense Th2 immune response. Levels of IL-17A increased rapidly in mice after the first immunization with HBc-N144-NspA, indicating the potential for this vaccine to induce a mucosal immune response. Meanwhile, the immunization of HBc-N144-NspA without adjuvant induced only mild inflammatory infiltration into the mouse muscle tissue.

Conclusion

This study demonstrates that modification using HBc renders NspA a candidate vaccine, which can trigger protective immunity against NMB.