Abstract: It is to provide intestinal symbiotic bacteria having an action of increasing an IgA content in milk. An agent containing one or more bacterial strains selected from: a bacterial strain of the genus Bacteroides which has a 16S rRNA gene having at least 90% identity to the nucleotide sequence represented by SEQ ID NO: 1, and has an action of increasing an IgA antibody content in milk; and a bacterial strain of the genus Prevotella which has a 16S rRNA gene having at least 90% identity to the nucleotide sequence represented by SEQ ID NO: 2, and has an action of increasing an IgA antibody content in milk is used as an agent for increasing an IgA antibody content in milk.

Abstract: A mucosal vaccine composition for preventing bovine mastitis, comprising: an antigen derived from Staphylococcus aureus; and a nanogel comprising a polysaccharide having a cationic functional group and a hydrophobic functional group in side chains. By administering the composition to cattle, it is possible to enhance the titer of an antibody against Staphylococcus aureus immediately after the contact with the bacteria in the udder, and prevent the bovine mastitis.

Abstract: A mucosal vaccine for the prevention or treatment of microbial infections is described that is capable of inducing vaccine antigen-specific immune responses in an organism without the addition of a mucosal adjuvant. The mucosal vaccine comprises a composite of a nanogel comprising a hydrophilic polysaccharide having a cationic functional group and a hydrophobic cholesterol added thereto as a side chain and a vaccine antigen. The vaccine is administered via a mucosal route.

Abstract: A mucosal vaccine for the prevention or treatment of microbial infections is described that is capable of inducing vaccine antigen-specific immune responses in an organism without the addition of a mucosal adjuvant. The mucosal vaccine comprises a composite of a nanogel comprising a hydrophilic polysaccharide having a cationic functional group and a hydrophobic cholesterol added thereto as a side chain and a vaccine antigen. The vaccine is administered via a mucosal route.

Abstract: A mucosal vaccine for the prevention or treatment of microbial infections is described that is capable of inducing vaccine antigen-specific immune responses in an organism without the addition of a mucosal adjuvant. The mucosal vaccine comprises a composite of a nanogel comprising a hydrophilic polysaccharide having a cationic functional group and a hydrophobic cholesterol added thereto as a side chain and a vaccine antigen. The vaccine is administered via a mucosal route.

Abstract: To provide a transgenic rice plant that can produce rice which can be used as an “edible vaccine”, i.e., rice capable of inducing a desired immune response when mucosally administered such as an oral administration. There is provided a transgenic rice plant including a genomic DNA, wherein a DNA construct is incorporated into the genomic DNA so that the DNA construct is capable of being expressed, wherein the DNA construct includes a DNA encoding an antigenic protein, and a rice endosperm specific promoter linked upstream thereof.