Induction of antibody response in the oral cavity of dogs following intraocular (eye drop) immunization with porphyromonas gingivalis cell lysate incorporated in pH-sensitive fusogemic polymer-modified liposomes

Induction of mucosal immune responses against Porphyromonas gingivalis within the oral cavity of dogs was studied by immunizing with pH-sensitive fusogenic polymer (MGIuPG)-modified liposome-associated cell lysate. Dogs immunized with P gingivalis cell lysatecontaining MGIuPG-modified liposomes by intraocular (eye drop) route displayed significant levels of P. gingivalis cell lysate-specific serum IgG and IgA as well as mucosal IgA antibodies in saliva secretion. Serum and salivary antibodies generated by intraocularly immunized with MGIuPG-modified liposome-associated P. gingivalis cell lysate revealed a significant aggregation activity against P gingivalis, whereas serum and saliva from dogs receiving MGIuPG-modified liposomes unentrapping P. gingivalis cell lysate did not show the aggregation activity against P gingivalis. Furthermore, P. gingivalis-specific antibodies in saliva of immunized dogs inhibited the adherence of P. gingivalis to cultured HeLa cells. More importantly, salivary antibodies induced by intraocular immunization with P. gingivalis cell lysate-containing MGIuPG-modified liposomes significantly inhibited the coaggregation of P gingivalis with Actinomyces naeslundii and the cell damage activity of P. gingivalis against FaDu cells, an oral epithelial cell. These results suggest that intraocularly administered P gingivalis cell lysate-containing MGIuPG-modified liposomes should be an effective mucosal vaccine against P. gingivalis infection in dogs and may be an important tool for the prevention of periodontitis.