Intranasal Delivery of Whole Cells of Neisseria Species: Study of Cross - Reactive Antigens in Rabbits

Abstract

Neisseria lactamica, a commensal bacterium that is non-pathogenic to human beings and that is usually found in the upper respiratory tract of children, is closely related to the pathogenic species Neisseria meningitidis. A protocol was proposed to study the immunogenicity of killed whole cells of N. lactamica, N. meningitidis, N. sicca or N. meningitidis c (carrier-isolated) by i.n. immunization in rabbits,considering the natural pathogen entry route. Adult rabbits were inoculated i.n with oropharynx-isolated N. lactamica, N. meningitidis, N. sicca or N. meningitidis carrier strain (c), at a concentration of 1.0 optical density unit at 650nm in a volume of 500 L. The rabbits were immunized four times at sevendays intervals. The rabbits developed levels of specific IgG antibodies in serum, as determined by ELISA using whole cells of homologous and heterologous strains. Serum from rabbits immunized with N. lactamica, N. meningitidis, and N. sicca or N. meningitidis c strain, showed IgG antibodies reactive to 5 to 190kDa antigens on immunoblotting with high avidity.

Prime-Boost Immunogenicity of Class 5C Protein from Neisseria meningitidis in Mice with Different Adjuvants

“…We conclude that intranasal immunization is effective in generating high levels of antibodies that appear as early as 10 days following intramuscular immunization. This is in accordance with the previous observation that mucosal immunization is important for obtaining significant antibody responses [43,44]. The antibody titers produced depended on the adjuvant used.…”

“…Since the nasopharynx is the only natural habitat of meningococci, intranasal immunization with meningococcal antigens has been suggested to be an effective way of inducing both mucosal and systemic immunity. Recent studies of OMVs administered intranasally in rabbit and humans have provided support for this strategy [37][38][39][40][41][42][43][44].…”

Neisseria lactamicaantigens complexed with a novel cationic adjuvant

“…4,5 Natural immunity against N. meningitidis is acquired during childhood and adolescence through the successive colonization by a commensal Neisseria carrier, N. meningitidis, as well as other bacteria genera that share cross-reactive antigens. [6][7][8] In particular, the importance of N. lactamica in this natural immunity has been investigated. [6][7][8] Particulate vaccines to Neisseria are currently receiving a high level of interest.…”

“…[6][7][8] In particular, the importance of N. lactamica in this natural immunity has been investigated. [6][7][8] Particulate vaccines to Neisseria are currently receiving a high level of interest. 9 Also, examining the quality of the antibodies colonization of the nasopharynx by non-pathogenic Neisseria species, including N. lactamica, has been suggested to lead to the acquisition of natural immunity against Neisseria meningitidis in young children.…”

Comparative proteomics analysis of two strains of Neisseria meningitidis serogroup B and Neisseria lactamica

“…Among nonpathogenic Neisseria species, N. lactamica shows close antigenic similarities with N. meningitidis. N. lactamica is a harmless commensal species and is more frequently colonized in the upper respiratory tract of infants and young children when compared to adults; its colonization rates decrease with increasing age (7)(8)(9). Previous studies have shown that development of crossprotective immunity against N. meningitidis will be seen in people who are carriers of N. lactamica.…”