An experiment was conducted with the objective to enhance mucosal immunity against ovalbumin (OVA) by co-administration of OVA with an aqueous extract from the fruit of Solanum torvum (STE). Five groups of female ICR mice aged approximately 8 weeks at the commencement of the experiment were caged in groups of eight and received various treatments. The treatments included OVA alone, OVA with cholera toxin (CT), and OVA with various doses of STE. Mice were primed intraperitoneally with 500 microg of OVA alone or co-administered with 0.1 microg CT, or with 1 microg STE. All mice were boosted orally via gastric intubation 14 days after priming with 10 mg OVA alone, or co-administered with 10 microg CT or with 10 mg, 1 mg or 0.1 mg STE. One week later all mice were killed and organs obtained for analysis of the immune response. Intestinal, faecal and pulmonary OVA-specific sIgA concentration was significantly increased (p<0.05) in mice that received booster combinations of OVA/CT and OVA with all extract doses (p<0.05). Specific serum IgG titres did not differ significantly between groups. It is concluded that STE can significantly enhance secretory immunity in the intestine to OVA with mucosal homing to the lungs. The adjuvant effect of STE is comparable to that of CT.
Matched MeSH terms: Immunoglobulin A, Secretory/blood
A gene associated with lipopolysaccharide (LPS) transport was cloned from a local clinical Vibrio cholerae O1 strain of the Ogawa serotype by using the Lactococcus lactis nisin-controlled expression (NICE) system. The V. cholerae wzm gene, which codes for an integral membrane transporter protein, was expressed and targeted to the cytoplasmic membrane, and was crudely isolated through simple centrifugation and SDS solubilization. To examine seroreactivity of this construct, rabbits were orally fed with 10(9) cfu/ml of live, recombinant L. lactis carrying the wzm gene, induced with nisin prior to administration. Recombinant plasmids were retrieved from L. lactis cultured directly from stool samples of inoculated rabbits. Reverse-transcriptase PCR of wzm using the retrieved plasmids confirmed transcription of this gene, indicating viability and stability of the recombinants in vivo. The L. lactis-Wzm construct elicited substantial levels of IgG and sIgA, and challenge with virulent V. cholerae O1 evoked severe diarrhoea in the naive, non-immunised control group, but not in those fed with either recombinant or non-recombinant L. lactis. Oral administration with recombinant L. lactis expressing the V. cholerae wzm gene increases both systemic and mucosal immunity, whereas L. lactis itself appears capable of protecting against the diarrhoeal symptoms caused by V. cholerae. Wzm is a conserved membrane protein associated with the LPS endotoxin, and together with the food-grade L. lactis, represent an attractive target for the development of a safer, live anti-infective therapy against V. cholerae.
Matched MeSH terms: Immunoglobulin A, Secretory/blood