血球在對抗病原及寄生蟲進入無脊椎動物宿主血腔扮演重要的角色。本研究美洲蟑螂(Periplaneta americana)經口自然食入縮小包膜絛蟲(Hymenolepis diminuta)蟲卵，蟑螂並不會產生包囊作用，而人為注射縮小包膜絛蟲蟲卵感染美洲蟑螂則會引起包囊作用。利用Zymography分析結果顯示注射蟲卵6小時及24小時出現分子量65 kDa的Gelatinase酵素活性與包囊作用的過程呈正相關，酵素抑制試驗結果顯示，分子量65 kDa的Gelatinase bands可被Cysteine proteinase抑制劑Leupeptin抑制，而二價陽離子螯合劑EDTA、Serine proteinase抑制劑PMSF及Metalloproteinase抑制劑Phenanthroline並不影響此酵素活性。因此確認此65 kDa的Gelatinase為Cysteine proteinase類的酵素。此酵素的活性與包囊作用的形成呈正相關，此結果顯示分子量65 kDa的Cysteine proteinase可能與蟑螂對縮小包膜絛蟲蟲卵的包囊作用相關。本研究在病媒生物學上定一個重要的進展，瞭解縮小包膜絛蟲與宿主專一性的問題。
Haemocytes play an essential role in defending invertebrates against pathogens and parasites that enter their haemocoel. In the present study, the cockroach, Periplaneta americana were not encapsulated the Hymenolepis diminuta eggs. However, the H. diminuta eggs can be encapsulate within 24 h after injection. Proteolytic activity of extracts was determined by using gelatinase zymography. This gelatinase has a molecular weight about 65 kDa, Ca/sup 2+/ dependency, and produced maximal activity in the pH range of 6-8. Enzyme activity was obviously inhibited by leupeptin; however, this study is important advancements in vector biology. The aim is to understand the host-specificity of this parasite and P. americana.
