Objective: This study aims to use Arginine-gingipain A gene vaccine (pVAX1-rgpA) to immunize adult Beagle dogs and to evaluate its effect during peri-implantitis progression and development.
Methods: Plasmid pVAX1-rgpA was constructed. The second and third bilateral mandible premolars of 15 adult Beagle dogs were extracted, and the implants were placed immediately. After 3 months, the animals were randomly divided into groups A, B, and C. Afterward, the animals were immunized thrice with plasmid pVAX1-rgpA, with heat-killed Porphyromonas gingivalis, or pVAX1, respectively. IgG in the serum and secretory IgA (sIgA) in saliva were quantitatively analyzed by enzyme-linked immunosorbent assay before and after 2 weeks of immunization. Peri-implantitis was induced with cotton ligatures fixed around the neck of implants. Probing depth (PD) and bleeding on probing were recorded. All animals were sacrificed after ligaturation for 6 weeks. Decalcified sections with thickness of 50 μm were prepared and dyed with methylene blue to observe the bone phenotype around implants.
Results: Levels of serum IgG and sIgA in saliva were higher in groups A and B after immunization than before the process (P<0.05) and higher than those in group C (P<0.05). However, no difference was observed between groups A and B (P>0.05). At 4 and 6 weeks after ligaturation, PD of the ligatured side in group C was higher than that in groups A and B (P<0.05). On the other hand, no difference was identified between groups A and B (P>0.05). Bone loss in group A was significantly lower than that of the other groups (P<0.05). Abundant inflammatory cells and bacteria were present in the bone loss area around the implants in the three groups, as identified through hard tissue section observation. However, group C presented the most number of inflammatory cells and bacteria in the bone loss area around the implants.
Conclusions: IgG and sIgA can be generated by immunity with rgpA DNA vaccine, which can significantly slow down bone loss during experimental peri-implantitis in dogs.
目的 构建牙龈卟啉单胞菌精氨酸特异性牙龈素基因疫苗pVAX1-rgpA，并对成年犬进行免疫接种，观察该疫苗在防治种植体周围炎发生发展中的作用。方法 构建真核表达质粒pVAX1-rgpA。拔除15只成年犬下颌双侧第二、三前磨牙，随机即刻植入种植体。3个月后，实验犬随机均分成A、B、C组，分别接种重组质粒pVAX1-rgpA、热失活牙龈卟啉单胞菌、空白质粒pVAX1，连续接种3次。接种开始前、接种结束2周后采用酶联免疫吸附试验检测血清IgG和唾液分泌型IgA（sIgA）含量。随机选取一侧采用丝线结扎法构建种植体周围炎，并检测种植体周探诊深度（PD）和探诊出血指数（BOP）。结扎6周后处死所有动物，制作50 μm厚的硬组织切片，亚甲基蓝染色后观察种植体周骨丧失程度。结果 A、B组动物免疫后，IgG、sIgA抗体较未免疫前明显增高（P<0.05），同时较C组升高（P<0.05），但A、B组间差异无统计学意义（P>0.05）。丝线结扎第4和6周时，C组结扎侧的PD明显高于A、B组（P<0.05），A、B组间差异无明显统计学意义（P>0.05）。A组结扎侧骨丧失量明显小于其他两组（P<0.05）。硬组织切片可见，各组种植体周骨丧失区均有大量的炎症细胞和细菌存在，C组结扎侧最严重。结论 精氨酸特异性牙龈素（rgpA）基因疫苗产生的IgG和sIgA，能有效减弱犬种植体周围炎的骨丧失量。.
Keywords: Arginine-gingipains; Porphyromonas gingivalis; dental implant; gene vaccine; peri-implantitis.