Oral Immunization with AttenuatedSalmonella entericaSerovar Typhimurium EncodingCryptosporidium parvumCp23 and Cp40 Antigens Induces a Specific Immune Response in Mice

Abstract

Attenuated Salmonella enterica serovar Typhimurium vaccine strain SL3261 was used as an antigen delivery system for the oral immunization of mice against two Cryptosporidium parvum antigens, Cp23 and Cp40. Each antigen was subcloned into the pTECH1 vector system, which allows them to be expressed as fusion proteins with highly immunogenic fragment C of tetanus toxin under the control of the anaerobically inducible nirB promoter. The recombinant vector was introduced into Salmonella Typhimurium vaccine strain SL3261, and the stable soluble expression of the chimeric protein was evaluated and confirmed by Western blotting with polyclonal C. parvum antisera. Mice were inoculated orally with a single dose of SL3261/pTECH-Cp23 or Cp40, respectively, and plasmid stability was demonstrated both in vitro and in vivo. Specific serum immunoglobulin G (IgG) antibodies against the Cp23 or Cp40 antigen were detected by enzyme-linked immunosorbent assay 35 days after immunization. Also, serum IgA and mucosal (feces) IgA antibodies were detected in 30% of the mice immunized with Cp23. In addition, prime-boosting with Cp23 and Cp40 DNA vaccine vectors followed by Salmonella immunization significantly increased antibody responses to both antigens. Our data show that a single oral inoculation with recombinant S. Typhimurium SL3261 can induce specific antibody responses to the Cp23 or Cp40 antigen from C. parvum in mice, suggesting that recombinant Salmonella is a feasible delivery system for a vaccine against C. parvum infection.

Oral Vaccination with AttenuatedSalmonella entericaStrains Encoding T-Cell Epitopes from Tumor Antigen NY-ESO-1 Induces Specific Cytotoxic T-Lymphocyte Responses

“…In this study, we used a site-specific chromosomal gene replacement system (35,37) to introduce foreign DNA encoding a heterologous peptide into agfA, which encodes the major subunit of Salmonella thin aggregative fimbriae. The bacterial strain used in our study was S. Typhimurium SL3261, which is aroA deficient and attenuated (2,15,24). We have also demonstrated that the inserted chimeric ESO9 gene and ESO11 gene, which were recombined into the chromosome of S. Typhimurium SL3261, can be expressed and that an epitopespecific T-cell response was induced in transgenic mice by this recombinant organism.…”

Serum IgG Response to Cryptosporidium Immunodominant Antigen gp15 and Polymorphic Antigen gp40 in Children with Cryptosporidiosis in South India

“…are endemic. Both gp15 and gp40 are surfaceassociated glycopeptides that are actively involved in the process of sporozoite attachment to and invasion of host cells and that induce antibody and cell-mediated immune responses and are therefore attractive vaccine candidates (10,26,51). This study is an initial step in determining whether either or both of these antigens could be targeted for vaccine development.…”

“…Most of the polymorphisms are clustered in the hypervariable region of the gp40 part of the molecule, while gp15 is relatively conserved (31,38,50). Although gp40 has been shown to induce humoral and cell-mediated immune responses in mice (10,47), it is not known whether this protein is immunogenic in infected humans or whether immune responses to it are species or subtype specific.…”

Treatment of Cryptosporidiosis

“…Both humoral and cellular responses were elicited using a Salmonella strain-andvector combination that delivered Cp23 and Cp40 fused to the C-terminal fragment of tetanus toxin (Benitez et al 2009). In another study, three antigens, Cp15, profilin, and a Cryptosporidium apyrase, were delivered in a heterologous primeboost regimen as fusions with cytolysin A (ClyA) in a Salmonella live vaccine vector and as purified recombinant antigens, and were found to induce specific and potent humoral and cellular immune responses (Manque et al 2011).…”