Galleria mellonella Invertebrate Model Mirrors the Pathogenic Potential of Mycoplasma alligatoris within the Natural Host

Abstract

Most mycoplasmal infections result in chronic, clinically silent disease. In direct contrast, Mycoplasma alligatoris elicits a fulminant, multisystem disease in the natural host, Alligator mississippiensis (American alligator). The goals of the study were to better understand the disease in the natural host and to determine if the invertebrate model G. mellonella could serve as a surrogate alternate host. The survival of alligators infected intratracheally was dose dependent ($p=0.0003$), ranging from no mortality (102 CFU) to 100% mortality (108 CFU), with 60% mortality at the 104 and 105 CFU infectious dose. Microbial load in blood, joints, and brain was dose dependent, regardless of whether alligators were infected intratracheally or intravenously ($p<0.002$). Weight loss was similarly impacted ($p<0.001$). Experimental infection of the invertebrate Galleria mellonella mirrored the result in the natural host. In a dose response infection study, both larval survival curves and successful pupation curves were significantly different ($p\le 0.0001$) and dose dependent. Infected insects did not emerge as moths ($p<0.0001$). Here, we describe the first study investigating G. mellonella as a surrogate model to assess the pathogenic potential of M. alligatoris. G. mellonella survival was dose dependent and impacted life stage outcome.