Uptake and replication of Salmonella enterica in Acanthamoeba rhysodes.
The ability of salmonellae to become internalized and to survive and replicate in amoebae was evaluated by using three separate serovars of Salmonella enterica and five different isolates of axenic Acanthamoeba spp. In gentamicin protection assays, Salmonella enterica serovar Dublin was internalized more efficiently than Salmonella enterica serovar Enteritidis or Salmonella enterica serovar Typhimurium in all of the amoeba isolates tested. The bacteria appeared to be most efficiently internalized by Acanthamoeba rhysodes. Variations in bacterial growth conditions affected internalization efficiency, but this effect was not altered by inactivation of hilA, a key regulator in the expression of the invasion-associated Salmonella pathogenicity island 1. Microscopy of infected A. rhysodes revealed that S. enterica resided within vacuoles. Prolonged incubation resulted in a loss of intracellular bacteria associated with morphological changes and loss of amoebae. In part, these alterations were associated with hilA and the Salmonella virulence plasmid. The data show that Acanthamoeba spp. can differentiate between different serovars of salmonellae and that internalization is associated with cytotoxic effects mediated by defined Salmonella virulence loci.
Tezcan-Merdol
Dilek
D
Microbiology and Tumor Biology Center, Karolinska Institute, 171 77 Stockholm, Sweden.
Ljungström
Marianne
M
Winiecka-Krusnell
Jadwiga
J
Linder
Ewert
E
Engstrand
Lars
L
Rhen
Mikael
M
D000048:Acanthamoeba / Q000382:microbiology* / Q000648:ultrastructure; D000818:Animals; D001426:Bacterial Proteins; D002460:Cell Line; D015169:Colony Count, Microbial; D003470:Culture Media; D004285:Dogs; D006801:Humans; D008854:Microscopy, Electron; D019779:Salmonella enterica / Q000145:classification / Q000235:genetics / Q000254:growth & development* / Q000472:pathogenicity*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014774:Virulence
D001426:Bacterial Proteins; D003470:Culture Media; C102236:HilA protein, Salmonella; D015534:Trans-Activators