The Effect Of Serpins From Ovary Of Rhipicephalus Haemaphysaloides On Tick Feeding And Oviposition

Tick is a common hemorrhagic arthropod as well as an important disease transmission vector.It can transmit parasitic diseases,viral diseases,bacterial diseases,spirochetes,etc.Tick and tick infectious diseases have been one of the major problems plaguing the animal husbandry in many countries in the world and China.Serpin is structurally altered and tightly bound to the corresponding target protease complex,resulting in inactivation of both.This reaction is irreversible and is therefore known as a "suicidal" inhibitor.Several Serpin molecules from tick ovary have been cloned in the early stage,but their biological functions have not been studied.Therefore,it is of great value to understand the biological function of these tick Serpin molecules and to provide basic theories for the discovery of new drugs for tick control.A number of Serpin molecules from the ovary of r.haemaphysaloides were studied.Firstly,the expression vectors constructed from nine Serpin genes from RHS3 to RHS11 were purified Then Western blot was used to analyze the expression characteristics of these molecules in different stages of tick development and different tissues and organs.The results showed that the Serpin molecule was secreted into the host through saliva during the feeding process in young,adult and adult ticks.In terms of the expression of Serpin in different tissues and organs,RHS3,RHS9 and RHS10 were all specifically expressed in the ovary,RHS6 and RHS7 are specifically expressed in salivary glands,while RHS4 was mostly specifically expressed in the adipose body.Proteins of RHS5 and RHS8 were expressed in multiple organs such as ovary,salivary glands and adipose body,but RHS11 was not found to be expressed in each organ.Secondly,the Serpin gene of 9 ticks from RHS3 to RHS11 was knocked down,and the feeding time,satiety weight and oviposition of the ticks were observed by RNA interference experiment,so as to explore its role in blood feeding and oviposition.By collecting the female ticks with 5d blood absorption,the ovary,midgut,salivary glands and adipose body were collected after dissection,and the gene knockout level was detected by fluorescence quantitative PCR.The results showed that RNA interference effectively reduced the expression of Serpin gene.After gene interference,RHS3 and RHS7 were down-regulated,which significantly reduced the blood-sucking capacity of female ticks in fimbrium falcatum.RHS8 significantly reduced the ovarian hatching rate of female ticks,while other Serpin did not significantly affect the blood-sucking and ovipositation of ticks.Thus,this thesis preliminarily clarified that Serpin molecules derived from ovaries play different roles in biological functions such as blood sucking and egg laying,and identified some potential applications of Serpin molecules,which provided data basis for the prevention and treatment of tick and tick-borne diseases.