SVWC Of Macrobrachium Nipponense Participating In Antimicrobial Immune Response

Macrobrachium nipponense is a very important economic shrimp in freshwater aquaculture in China,which has great fishery benefits.With the pollution of water environment,the irregularity of breeding methods and diseases,it will cause great economic losses every year.Therefore,it is very important to study the immune system of Macrobrachium nipponense,especially the anti-bacterial immunity,for the scientific breeding and disease prevention of Macrobrachium nipponense.The SVWC protein family is a small molecule protein family found in invertebrates that contain eight conserved cysteine structures.Studies have shown that SVWC proteins play an important role in response to environmental stimuli,changes in nutritional status,viral infection and bacterial stimuli.However,previous studies on SVWC protein mainly focused on SVWC to help invertebrates resist viral infection,and few reports have been reported on SVWC's involvement in the antimicrobial immune function of invertebrates.In this study,a SVWC gene was selected based on the self-test of macrobrachium japonensis transcriptome in the laboratory.We named it MnSVWC,and studied the role of MnSVWC in the antimicrobial immune function of Macrobrachium nipponense.The main research results are as follows:1.The expression patterns of MnSVWC in different tissues of Macrobrachium nipponense were analyzed,and the expression changes of MnSVWC gene were analyzed after Aeromonas virginiae was used to stimulate Macrobrachium nipponense by q-PCR.The results showed that MnSVWC was the highest in the gill tissue and hemolymph of Macrobrachium nipponense,and the expression of MnSVWC was significantly up-regulated by Aeromonas virginiae after stimulation of Macrobrachium nipponense.2.The MnSVWC protein was successfully expressed in Escherichia coli by prokaryotic expression system,and the active rMnSVWC protein was purified.In this study,we found that rMnSVWC protein could agglutinate Escherichia coli,Staphylococcus aureus,Bacillus subtilis and Aeromonas virginia in the presence of calcium ions,and we found that rMnSVWC could bind to these four bacteria by Western blot.The bacteria treated with MnSVWC were observed by scanning electron microscopy.It was found that MnSVWC could not kill bacteria directly.3.The bacteria were co-incubated with MnSVWC and injected into the Macrobrachium nipponense.It was found that MnSVWC could promote the removal of bacteria from the body of Macrobrachium nipponense.After RNAi knocked down the expression of MnSVWC,the ability of the prawn to clear bacteria was significantly reduced.4.Using confocal microscopy and immunofluorescence technique,we found that MnSVWC protein not only binds to the blood cells of Macrobrachium nipponense,but also promotes the blood cel s to phagocytize the invading bacteria.