Antibody Responses, Histopathological Changes and Immunohistochemical Evidence of Cholinergic Neuroimmune Interactions in Lymphoid Tissues in Mice Immunized with Lactococcus Lactis Expressing a Malaria Parasite Protein

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Introduction: Gram positive food grade bacteria Lactococci have significant advantages over attenuated pathogens a s vaccine delivery vehicles due to inherent safety. Methods: Plasmodium falciparum merozoite surface antigen2(PfMSA2) w as expressed in recombinant Lactococcus lactis. Recombinant L.lactis strain, delivered oro-nasally for mucosal immunisation to Balb/c mice. Non-recombinant L.lactis used as control. Serum antibody response investigated by E L IS A and immunofluorescence assay. Histopathological changes in gut associated lymphoid tissue investigated. The cholinergic nerve ending and the distribution of alpha subunits of n A C h R s in the spleen, Peyeris patches and mesenteric lymph nodes were studied by indirect immunohistochemistry Results: Serum IgG anti-MSA2 responses w as significantly higher in Balb/c mice, after oronasal delivery. Antibodies elicited reacted with native M SA 2 in the surface of P. falciparum merozoites in an immunofluorescence assay. Enlargement of mesenteric lymph nodes and increased lymphatic infiltration of the lamina propria were noted. Spleen showed periarteriolar lymphoid aggregation iri immunized mice. The a1 n A C h R s were distributed in the capsule and red pulp of spleen. Germinal centres of Peyeris patches showed diffuse( +1) distribution of a ln A C h R and expressed a low immunoreactivity(IR) of anti-nAChRs. Conclusions: Recombinant L. lactis is a suitably safe vector for subunit vaccines. Neuronal control of immune response by parasympathetic cholinergic innervation through n A C h R s is suggestive.