Nasal immunisation with Salmonella typhimurium producing rotavirus VP2 andVP6 antigens stimulates specific antibody response in serum and milk but fails to protect offspring

Rotavirus specifically infects the small intestine of young infants resulti ng in severe diarrhoea. Mucosal antibody responses are required to cure the infection, and mucosal administration of rotavirus-like particles induces protective immunity without requiring a mucosal adjuvant such as cholera to xin. In addition. the rotavirus protein VP6 has been defined as a protectiv e antigen in an adult mouse rotavirus infection model. Salmonella typhimuri um is an epithelium-invasive bacterium that induces specific immune respons es in mucosal tissues against itself and carried antigens. In this work, we investigated the capacity of alive recombinant S. typhimurium vaccine to s timulate antibody responses against rotavirus. We constructed an attenuated S. typhimurium strain simultaneously producing VP6 and VP2 rotavirus prote ins in the cytoplasm. In contrast to expression in eukaryotic cells, VP6 an d VP2 did not form virus-like particles in our bacterial system. After nasa l administration of female mice, the live recombinant Salmonella were able to elicit an antibody response specific to both VP2 and VP6 in serum and mi lk. However, these antibodies failed to passively protect the offspring aga inst rotavirus-induced diarrhoea. (C) 2001 Elsevier Science Ltd. All rights reserved.