Evaluation of the immunogenic property of NT H. influenzae protein D with Neisseria meningitidis OMV in BALB/c

Abstract

Introduction: Identifying ideal non typeable Haemophilus influenzae (NTHi) vaccine candidates has not been easy due to extensive sequence and antigenic variation among gene products interacting with the immune system. Protein D (PD) is a highly conserved 42 kDa surface lipoprotein available in all H. influenzae, including NTHi. Methodology: In this study, the gene encoding PD was cloned from H. influenzae and expressed in Escheriachia coli TOPO10 cell in pBAD vector. Arabinose was used to express recombinant protein. In order to purify the protein, Ni-NTA agarose was used to perform affinity chromatography. Purified PD and PD mixed with outer membrane vesicle (OMV) and alum adjuvant were used for subcutaneous immunization in BALB/c mice. After vaccination, IgG responses to PD-OMV, PD-alum, and PD alone were determined by enzyme-linked immunosorbent assay (ELISA). Results: The recombinant PD containing His6 residues showed a molecular weight of 42 kDa. Anti-PD IgG was detected after first immunization in all groups of mice compared to the negative control group, and it increased after first vaccination, but results showed that the addition of OMV to PD led to a remarkable increase in IgG responses. Conclusions: Our results suggest an important role for OMV as an adjuvant and show how it could potentially be used when conjugated to H. influenzae PD or other safe subunit vaccine candidates.

Evaluation of immunological responses against outer membrane vesicles (OMV) of nontypeable Haemophilus influenzae using MPLA -CpG adjuvant as a vaccine candidate

“…COPD as a major public health problem is mostly observed in newborn infants and one third of children will be expected to die per year, by 2020 from this devastating disease (11). Due to the loss of protective capsules in non-capsular strains, as well as the presence of variable phenotypes and genotypes, effective and potent vaccine against NTHi strains is not available yet, and according to reports of aggressive diseases and increased drug resistance against these strains, it seems necessary to make an effective vaccine against these strains (9,12).…”

“…In this context, OMVs can be considered as a new candidate for a vaccine. Due to the presence of various compounds, such as outer membrane proteins, lipopolysaccharide, peptidoglycan and the recent discovery of DNA and RNA in the OMV structure, it can be stated that OMV is a carrier of several native bacterial antigens and is therefore important for the development of the vaccine (9,19). The significant properties of membrane antigens and their surface exposure in OMV have led to the confirmation of structural, physicochemical stability and the protective and genomic properties of OMV in many bacteria.…”

“…The significant properties of membrane antigens and their surface exposure in OMV have led to the confirmation of structural, physicochemical stability and the protective and genomic properties of OMV in many bacteria. OMV is involved in the formation of biofilms, binding to the host cell, intra and intercellular transmission, antibiotic resistance, competitive death responses among microorganisms, response to stress and the maturi-ty of immune cells (9,20). Considering the studies performed in these regards, and the role of OMV in binding and the increased pathogenicity of H. influenzae, and the possibility of stimulating the immune system; in the present study, we decided to use this structure as a new vaccine candidate, and to examine the protective immune responses and also, to evaluate the cytotoxicity effect in the presence of these structures.…”

Exosome-Based Vaccines: History, Current State, and Clinical Trials

“…Another exosome-based vaccination approach to combat the influenza virus includes EVs released by gram-negative bacteria, which are referred to as outer membrane vesicles (OMVs) (157). Several recent studies have reported that OMV-derived vaccines can induce strong immune protection against the influenza virus in vivo (158)(159)(160)(161).…”

Vaccine Candidates against Nontypeable Haemophilus influenzae: a Review

“…The interaction between H. influenzae and the immune system is occurred by the binding of IgD to its surface[ 56 ]; this interaction is shared with Moraxella (Branhamella) catarrhalis with unknown reasons. All 127 H. influenzae strains, including encapsulated serotypes a–f and NTHi, have this antigenically conserved 42-kDa protein[ 57 ], making it an attractive vaccine candidate. A 1092 bp open reading frame of hpd encodes a 364-amino acid protein.…”