AUTHOR=Thelaus Johanna , Lundmark Eva , Lindgren Petter , Sjödin Andreas , Forsman Mats 

TITLE=Galleria mellonella Reveals Niche Differences Between Highly Pathogenic and Closely Related Strains of Francisella spp.

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=8

YEAR=2018

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2018.00188

DOI=10.3389/fcimb.2018.00188

ISSN=2235-2988

ABSTRACT=<p><italic>Francisella tularensis</italic>, a highly virulent bacteria that causes the zoonotic disease tularemia, is considered a potential agent of biological warfare and bioterrorism. Although the host range for several species within the <italic>Francisella</italic> is known, little is known about the natural reservoirs of various <italic>Francisella</italic> species. The lack of knowledge regarding the environmental fates of these pathogens greatly reduces the possibilities for microbial risk assessments. The greater wax moth (<italic>Galleria mellonella)</italic> is an insect of the order <italic>Lepidoptera</italic> that has been used as an alternative model to study microbial infection during recent years. The aim of this study was to evaluate <italic>G. mellonella</italic> as a model system for studies of human pathogenic and closely related opportunistic and non-pathogenic strains within the <italic>Francisella</italic> genus. The employed <italic>G. mellonella</italic> larvae model demonstrated differences in lethality between human pathogenic and human non-pathogenic or opportunistic <italic>Francisella</italic> species. The <italic>F. novicida, F. hispaniensis</italic> and <italic>F. philomiragia</italic> strains were significantly more virulent in the <italic>G. mellonella</italic> model than the strains of human pathogens <italic>F. t. holarctica</italic> and <italic>F. t. tularensis</italic>. Our data show that <italic>G. mellonella</italic> is a possible <italic>in vivo model</italic> of insect immunity for studies of both opportunistic and virulent lineages of <italic>Francisella</italic> spp., that produces inverse results regarding lethality in <italic>G. mellonella</italic> and incapacitating disease in humans. The results provide insight into the potential host specificity of <italic>F. tularensis</italic> and closely related members of the same genus, thus increasing our present understanding of <italic>Francisella</italic> spp. ecology.</p>