[ODP-022] Pathogenic characterization of hemolytic Rodentibacter sp. isolated from laboratory rodents
Rodentibacter spp. is opportunistic pathogen that is often detected and isolated from upper respiratory tracts of laboratory rodents. In particular, R. pneumotropicus and R. heylii is one of preventive agents in rodent colony because they are known to cause lethal pneumoniae and sepsis in immunodeficient animals. In this study, the isolates that could not be identified as species level but were only predicted to Rodentibacter sp. were characterized based on molecular and pathogenic analysis. The draft genome sequencing indicated that Rodentibacter sp. possess 2.4 Mb circular genome and 2.6 kb cryptic plasmid, and the genes coding for virulent proteins were identified as mainly hemolysins and adhesins. A 110 kDa of RTX toxin that was extracted and purified from culture supernatant with using ammonium sulfate precipitation indicated highly cytotoxicity toward RAW 264.7 macrophage cells. Experimental infection of Rodentibacter sp. intranasally with BALB/C-Rag2-/- mice showed 80% lethality and was not significantly different from that of R. pneumotropicus type strain ATCC 35149 with using Log-rank test. These results suggested that RTX toxin positive-Rodentibacter sp. is pathogenic to immunodeficient rodents and is an agent that requires prevention of infection in laboratory rodent colony.