Highly Conserved Neisseria meningitidis Surface Protein Confers Protection against Experimental Infection

Abstract

A new surface protein, named NspA, which is distinct from the previously described Neisseria meningitidis outer membrane proteins was identified. An NspA-specific mAb, named Me-1, reacted with 99% of the meningococcal strains tested indicating that the epitope recognized by this particular mAb is widely distributed and highly conserved. Western immunoblotting experiments indicated that mAb Me-1 is directed against a protein band with an approximate molecular mass of 22,000, but also recognized a minor protein band with an approximate molecular mass of 18,000. This mAb exhibited bactericidal activity against four meningococcal strains, two isolates of serogroup B, and one isolate from each serogroup A and C, and passively protected mice against an experimental infection. To further characterize the NspA protein and to evaluate the protective potential of recombinant NspA protein, the nspA gene was identified and cloned into a low copy expression vector. Nucleotide sequencing of the meningococcal insert revealed an ORF of 525 nucleotides coding for a polypeptide of 174 amino acid residues, with a predicted molecular weight of 18,404 and a isoelectric point of 9.93. Three injections of either 10 or 20 μg of the affinity-purified recombinant NspA protein efficiently protected 80% of the mice against a meningococcal deadly challenge comparatively to the 20% observed in the control groups. The fact that the NspA protein can elicit the production of bactericidal and protective antibodies emphasize its potential as a vaccine candidate.

Characterisation of the Protein Content of a Meningococcal Outer Membrane Vesicle Vaccine by Polyacrylamide Gel Electrophoresis and Mass Spectrometry

“…For example: FetA was also identified in bands 7, 8 and 9; PorA in bands 16, 17, 18, 26, 28 and 29 and PorB in bands 14,15,16,17,18,20,24, 26 and 28. Other well documented membrane proteins identified included: Tbp1 (band 1), HmbR (band 3), TonB dependant receptors (bands 2, 3, 4 and 11) and PilQ (band 4).…”

“…Key proteins present in OMVs that are thought to have an important impact on protective immunity include: Omp85, 14 FetA, 15,16 PorA, 11 PorB, 17,18 RmpM, 19 OpcA 11 and NspA. 20 Currently, demonstration of the presence of these antigens in OMV vaccines is by one-dimensional (1-D) polyacrylamide gel electrophoresis (PAGE) in the presence of sodium dodecyl sulphate (SDS) and immunoblotting with monoclonal antibodies. However, the panel of monoclonal antibodies that recognise these proteins is not comprehensive, antibodies that recognise discontinuous epitopes cannot be used and it is difficult to identify all of these proteins on a 1-D gel by size alone.…”

Expression of the Iron-ActivatednspAandsecYGenes inNeisseria meningitidisGroup B by Fur-Dependent and -Independent Mechanisms

“…Neisserial surface protein A (NspA) is an 18.6-kDa membrane protein of unknown function that was first described to confer protection against meningococcal infection in animal models of infection (1,21,22). NspA is highly conserved and expressed by all N. meningitidis strains tested (22,25).…”

Neisseria meningitidis antigen NMB0088: sequence variability, protein topology and vaccine potential

“…The drawback with the OMV vaccines is that the most immunogenic components are highly variable and, consequently, these vaccines are not able to confer protection against a wide range of heterologous strains (Martin et al, 2000;Tappero et al, 1999). Alternatively, highly conserved N. meningitidis serogroup B membrane antigens have been sought and evaluated as vaccine candidates (Comanducci et al, 2002;Martin et al, 1997;Giuliani et al, 2006). The successful development of a broad-specificity serogroup B vaccine may be attained as a consequence of the genome sequencing of the serogroup B N. meningitidis strain MC58 (Tettelin et al, 2000), which has opened up new possibilities for identifying antigens to be included in candidate vaccines (Pizza et al, 2000).…”