Protective effect of intranasal immunization with Neospora caninum membrane antigens against murine neosporosis established through the gastrointestinal tract

Abstract

Summary Neospora caninum is an Apicomplexa parasite that in the last two decades was acknowledged as the main pathogenic agent responsible for economic losses in the cattle industry. In the present study, the effectiveness of intranasal immunization with N. caninum membrane antigens plus CpG adjuvant was assessed in a murine model of intragastrically established neosporosis. Immunized mice presented a lower parasitic burden in the brain on infection with 5 × 107 tachyzoites, showing that significant protection was achieved by this immunization strategy. Intestinal IgA antibodies raised by immunization markedly agglutinated live N. caninum tachyzoites whereas previous opsonization with IgG antibodies purified from immunized mice sera reduced parasite survival within macrophage cells. Although an IgG1 : IgG2a ratio < 1 was detected in the immunized mice before and after infection, indicative of a predominant T helper type 1 immune response, no increased production of interferon‐γ was detected in the spleen or mesenteric lymph nodes of the immunized mice. Altogether, these results show that mucosal immunization with N. caninum membrane proteins plus CpG adjuvant protect against intragastrically established neosporosis and indicate that parasite‐specific mucosal and circulating antibodies have a protective role against this parasitic infection.

A live auxotrophic vaccine confers mucosal immunity and protection against lethal pneumonia caused by Pseudomonas aeruginosa

“…Then, bacteria were harvested by centrifugation (3,900 g, 20 min, 4˚C), washed, suspended in sterile NaCl 0.9% and heat-inactivated by incubation at 100˚C for 2 h. Killing of bacteria was checked by plating on LB agar and overnight incubation at 37˚C. Quantification of IgA antibodies in VLF and BAL was performed by indirect ELISA according to [57], using secondary antibody alkaline phosphatase-conjugated anti-mouse IgA diluted 1:500. Plates were "coated" with formalin-inactivated PAO1, which was fixed to the bottom of the wells after overnight incubation at 4˚C in 100 mM carbonate-bicarbonate buffer, pH 9.6.…”

Protective effect of antigen delivery using monoolein-based liposomes in experimental hematogenously disseminated candidiasis

“…Specific anti-CWSP immunoglobulins in the collected serum were quantified by ELISA according to Ferreirinha et al [39]. Briefly, polystyrene microtitre plates (Nunc, Roskilde, Denmark)…”

Protective Effect against Neosporosis Induced by Intranasal Immunization with Neospora caninum Membrane Antigens Plus Carbomer-Based Adjuvant

“…Parasite concentration was determined in cell suspensions using a hemocytometer. Whole parasite sonicates and N. caninum antigen extracts enriched in parasite membrane proteins (NcMP) were prepared accordingly to previously described methodology [33]. Briefly, frozen tachyzoites were suspended in PBS containing 0.75% Triton X-14 and the organic phase was precipitated with 4 volumes of absolute ethanol.…”

“…Considering the preponderant role of IFN-γ in host protection against neosporosis, several vaccination strategies have stressed the induction of the production of this cytokine through selected antigen and adjuvants [27][28][29][30][31][32]. We have previously developed a mucosal immunization approach aimed at preventing N. caninum infection that used an extract of the parasite membrane antigens together with CpG oligodeoxynucleotide adjuvant to promote Th-1-type and humoral immunity [33]. This approach proved highly effective in protecting against N. caninum infection in the long term [34].…”