Recombinant Neisseria surface protein A is a potential vaccine candidate against Neisseria meningitides serogroup B

Neisseria meningitidis is the pathogen of epidemic encephalomyelitis and is responsible for permanent damage to the brain and nervous system. In the present study, the prokaryotic expression vector pGEX-6p-1/neisseria surface protein A (NspA) was constructed and the immune protective effect was investigated with the purified recombinant rNspA. Female BALB/c mice were immunized by intraperitoneal inoculation of rNspA, glutathione S-transferase (GST) or phosphate-buffered saline (PBS). The protection experiment in mice demonstrated that the protection rate of the rNspA group was 85% against the N. meningitidis strain MC58, and a serum bactericidal assay in vitro revealed that the serum bactericidal titer of the rNspA group reached 1:64 following three immunizations. The levels of specific immunoglobulin (Ig) A (SIgA), IgG, IgG1, IgG2a, IgG2b and IgG3 of mice in the rNspA group peaked at week six and were higher than those in the mice in the GST and PBS groups. The levels of stimulation index, interleukin-4 and interferon-γ in the culture supernatant of the spleen lymphocytes of the rNspA group increased in a time-dependent manner and were higher than those of the mice in the GST and PBS groups over the same period. The results suggested that rNspA may induce increased specific humoral and cellular immune responses, and that it is effectively protective against N. meningitidis serogroup B in mice. The present study offered novel evidence that may lead to the development of a novel effective N. meningitidis serogroup B vaccine.