| Trypanosoma evansi is a common parasitic protozoa that is transmitted by insects.It is the causative agent of trypanosomiasis(or Sula disease)in livestock.The parasite mainly parasitizes in the blood of various animals such as horses,baboons,camels,and cattle.It can cause animal wasting,anemia,and neurological symptoms.In addition,there have been reports of humans infected by T.evansi,suggesting that T.evansi is a potential zoonotic pathogen.Trypanosoma evansi has a complete immune evasion mechanism,and it is most typical to evade specific immunity by changing the surface variable glycoprotein(VSG).Because of the existence of this immune evasion mechanism,the existing specific vaccine for trypanosomiasis is not effective,and we urgently need to find a new way to prevent and treat Trypanosomiasis.In recent years,bacteriological studies have revealed that many bacteria secrete DNase to degrade the extracellular traps captured by immune cells to spread in the host.Previous studies in our group have found that the hosts infected by parasites can produce extracellular traps(ETs)to capture infested parasites,while parasites degradate DNA by secreting deoxyribonuclease(DNase).More importantly,animals immunized with Plasmodium DNase can achieve a great immune protection.Therefore,we speculate that T.evansi can also produce DNase to escape the natural immunity.The purpose of this project is to determine the function of the interaction between the parasite and the host by analyzing the biological and spatial characteristics of DNase in T.evansi.Firstly,we used bioinformatics to analyze target sequences and obtained two DNase sequences in T.evansi,TatD-like DNase1005 and TatD-like DNase-1155.Secondly,The qPCR was used to compare and analyze the transcriptional levels of the two target genes in T.evansi 805 and T.evansi YNB strains in vitro culture conditions and in animals.The results showed that the transcriptional levels of the TatD-like DNase 1155 and TatD-like DNase1005 genes were significantly higher in animals than in vitro culture conditions.Furthermore,the transcriptional level of these two genes in the T.evansi 805 strain was significantly higher than in the T.evansi YNB strain.Then,these two proteins were located around the trypanosomal membrane and flagellum by indirect immunofluorescence(IFA).Finally,analysis of the biochemical properties of the two recombinant proteins revealed that both proteins are divalent metal-dependent DNases.This experiment has initially verified the distribution and hydrolysis of TatD-like DNase in T.evansi,providing basis for the further study on the mechanism of trypanosomal immune evasion by hydrolyzing extracellular traps. |
