Periodontal disease, gingival
inflammation (
gingivitis) and
periodontal attachment loss (
periodontitis), causes
tooth loss and susceptibility to chronic
inflammation. Professionally scaling and cleaning the teeth regularly controls the disease, but is expensive in companion animals. Eikenella corrodens is common in canine oral cavities where it is a source of
lysine decarboxylase (LDC). In human dental biofilms (plaques), LDC converts
lysine to
cadaverine and impairs the gingival epithelial barrier to bacteria. LDC vaccination may therefore retard
gingivitis development. Year-old beagle dogs provided blood samples, and had weight and clinical measurements (biofilm and
gingivitis) recorded. After scaling and cleaning, two dogs were immunized subcutaneously with 0.2mg native LDC from E. corrodens and 2 sets of four dogs with 0.2mg recombinant LDC purified from Escherichia coli. A third set of 4 dogs was immunized intranasally. Rehydragel(®), Emulsigen(®), Polygen™ or Carbigen™ were used as adjuvant. Four additional pairs of dogs were
sham-immunized with each adjuvant alone (controls). Immunizations were repeated twice, 3 weeks apart, and clinical measurements were obtained after another 2 weeks, when the teeth were scaled and cleaned again. Tooth brushing was then stopped and the diet was changed from hard to soft chow. Clinical measurements were repeated after 1, 2, 3, 4, 6 and 8 weeks. Compared with
sham-immunized dogs,
gingivitis was reduced over all 8 weeks of soft diet after subcutaneous immunization with native LDC, or after intranasal immunization with recombinant LDC in Carbigen™, but for only 6 of the 8 weeks after subcutaneous immunization with recombinant LDC in Emulsigen(®) (repeated measures ANOVA). Subcutaneous vaccination induced a strong serum
IgG antibody response that decreased during the soft diet period, whereas intranasal immunization induced a weak serum
IgA antibody response that did not decrease. Immunization with recombinant LDC may provide protection from
gingivitis if procedures are optimized.