Abstract: Objective   To observe the inhibitive effect on invasive growth and metastasis of Echinococcus multolocularis by exogenous anti-osteopontin（OPN）antibody.  Methods   180 gerbils were infected with 20% E. multolocularis suspension（approximately 400 protoscoleces in 0.1 ml per gerbil）through abdominal opening injection in liver，and then divided into model group，experiment group and control group. Experiment group and control group each with 60 gerbils were injected via the tail vein with 0.15 ml of anti-OPN antibody（1 ∶ 32）and rabbit serum，respectively. All gerbils in the two groups received injections，with 2-day interval for the first seven injections，and then at 7-day interval for the remaining injections. Model group were without any treatment. The three groups were subdivided into six groups each with 10 gerbils. The gerbils from each group were sacrificed on day 1，20，40，60，80，and 100 after infection，respectively. Hepatic echinococcus cyst and metastasis tissue were observed. The expression of OPN was measured by immunohistochemistry staining（SP method）. Serum samples were collected at 100 d post-infection, and the content of OPN in  sera was measured by ELISA.  Results  There were no significant difference in cyst weight and metastatic rate of thoracic lymph node among the three groups at 1，20，40，60，and 80 d post-infection（P＞0.05），while at 100 d post-infection，cyst weight and metastatic rate of thoracic lymph node in experiment group［（7.28±0.38） g，20%］were lower than that of control group［（9.70±0.61） g，70%］and model group［（9.32±0.73） g，70%］（P＜0.05）. Expression of OPN was found at different levels in echinococcus cysts. OPN was located in the cytoplasm, and mainly distributed in the germinal layer. The OPN positive expression levels were not significantly different between experiment group and other groups on day 1，20，40，60，and 80 afer infection（P＞0.05）. At 100 d post-infection，OPN positive expression rate and serum OPN content in experimental group［20% and（30.90±2.25） ng/μl， respectively］was lower than that of control group［80% and （41.03±2.76） ng/μl］and model group［80% and （42.39±2.85） ng/μl］（P＜0.05）.   Conclusion   Anti-osteopontin antibody can reduce OPN concentration in hepatic echinococcus cyst and serum，and inhibit the invasive growth and metastasis of E. multolocularis.

Key words: Anti-osteopontin antibody, Alveolar echinococcosis, Invasive growth, Metastasis