P. gingivalis OMVs were used as a vaccine antigen for
intranasal immunization of BALB/c mice (Nakao et al.
2011). Synthetic double-stranded RNA polyriboinosinic
polyribocytycil [Poly (I:C)] was used as the mucosal adjuvant.
In mice vaccinated with such a vaccine, high levels
of P. gingivalis-specific IgA was found in nasal washes
and saliva, while IgA and IgG antibodies were found in
serum. They also found that the mutation of the galE gene
in P. gingivalis altered the production of OMVs resulting
in reduced OMVs per cell or no vesicles at all. Nakao et
al. (2006) previously had shown that mutations in the galE
gene in P. gingivalis caused accumulation of intracellular
carbohydrates in the presence of 0.1 % of galactose, a
shorter O-antigen chain, increasing of biofilm production,
and significantly more susceptible to some antibiotics in
comparison with the wild type. The absence of OMVs in
galE mutant is noteworthy as very little information related
to the mechanism of the production of vesicles is known