Characterization Of Galleria Mellonella Model For Highly Virulent Staphylococcus Aureus In Anhui Province

Staphylococcus aureus is a highly dangerous pathogen,it can cause infection in different parts of humans and animals,leading to a wide range of diseases,from relatively mild skin infections to life-threatening systemic diseases.One of the main reasons S.aureus has been so successful as a pathogen is that it can secrete a large number of virulence factors.These virulence factors manipulate the innate and adaptive immune responses of the host.Among these virulence factors,psmα and psmβ encoded phenolsoluble modulin(PSM)is a very important virulence factor,which participates in the process of various diseases caused by Staphylococcus aureus.In recent years,Galleria mellonella has been widely used as an animal models in the study of pathogen infection.It is particularly important to select a suitable animal infection model to study the pathogenic microorganism,and the growth cycle of G.mellonella is short,economical,convenient and need not consider the ethical issues.Previous studies have shown that there are many similarities in the structure and function of the immune system between the G.mellonella and human beings,so the G.mellonella was used as the experimental animal in this study.Our main objective in this study is to explore the genes of highly virulent strains using G.mellonella as an infection model,and to use the phenotype of G.mellonella infection as a virulence characterization of the bacteria,indentify genes related to high virulence,and provide ideas for the infection treatment of highly virulent clinical strains.Eight highly virulent clinical strains(21112741,21101007,21083150,21112607,X21111206,21122023,21092239,and 21122543)were screened based on the rupture of sheep erythrocytes.After that,the survival rate and virulence of S.aureus were calculated by constructing the infection model of the G.mellonella.The expression levels of virulence factors psmα and psmβ were detected by real-time quantitative PCR(q RT-PCR).The results showed that the expression levels of psmα and psmβ were significantly higher than those of NCTC8325(high virulence mode strain are commonly used as control groups).The results of survival rate showed that the virulence of three isolates(21112607,X2111206,21092239)was significantly higher than that of NCTC8325.Thus,the expression levels of psmα and psmβ were measured after the three isolates were cultured in TSB medium,the results showed that the expression level was higher in the blood of G.mellonella.These results indicate the feasibility of the G.mellonella as an animal model,and further prove that PSM is a very important virulence factor,which may be used as a new therapeutic target,provide some new ideas for clinical treatment of Staphylococcus aureus infection.