Heterogeneity of type III secretion system (T3SS)-1-independent entry mechanisms used by Salmonella Enteritidis to invade different cell types.
Salmonella causes a wide range of diseases from acute gastroenteritis to systemic typhoid fever, depending on the host. To invade non-phagocytic cells, Salmonella has developed different mechanisms. The main invasion system requires a type III secretion system (T3SS) known as T3SS-1, which promotes a Trigger entry mechanism. However, other invasion factors have recently been described in Salmonella, including Rck and PagN, which were not expressed under our bacterial culture conditions. Based on these observations, we used adhesion and invasion assays to analyse the respective roles of Salmonella Enteritidis T3SS-1-dependent and -independent invasion processes at different times of infection. Diverse cell lines and cell types were tested, including endothelial, epithelial and fibroblast cells. We demonstrated that cell susceptibility to the T3SS-1-independent entry differs by a factor of nine between the most and the least permissive cell lines tested. In addition, using scanning electron and confocal microscopy, we showed that T3SS-1-independent entry into cells was characterized by a Trigger-like alteration, as for the T3SS-1-dependent entry, and also by Zipper-like cellular alteration. Our results demonstrate for what is believed to be the first time that Salmonella can induce Trigger-like entry independently of T3SS-1 and can induce Zipper-like entry independently of Rck. Overall, these data open new avenues for discovering new invasion mechanisms in Salmonella.
IFR136 Agents Transmissibles et Infectiologie, Université de Tours, France.|INRA, UR1282 Infectiologie Animale et Santé Publique, F-37380 Nouzilly, France.
Manon
M
Rosselin
IFR136 Agents Transmissibles et Infectiologie, Université de Tours, France.|INRA, UR1282 Infectiologie Animale et Santé Publique, F-37380 Nouzilly, France.
Nadia
N
Abed
IFR136 Agents Transmissibles et Infectiologie, Université de Tours, France.|INRA, UR1282 Infectiologie Animale et Santé Publique, F-37380 Nouzilly, France.
Isabelle
I
Virlogeux-Payant
IFR136 Agents Transmissibles et Infectiologie, Université de Tours, France.|INRA, UR1282 Infectiologie Animale et Santé Publique, F-37380 Nouzilly, France.
Elisabeth
E
Bottreau
Département des Microscopies Plate-Forme RIO, INSERM ERI19, Université François Rabelais, Tours, France.|IFR136 Agents Transmissibles et Infectiologie, Université de Tours, France.
Pierre-Yves
PY
Sizaret
IFR136 Agents Transmissibles et Infectiologie, Université de Tours, France.|INRA, UR1282 Infectiologie Animale et Santé Publique, F-37380 Nouzilly, France.
Philippe
P
Velge
IFR136 Agents Transmissibles et Infectiologie, Université de Tours, France.|INRA, UR1282 Infectiologie Animale et Santé Publique, F-37380 Nouzilly, France.
Agnès
A
Wiedemann
D016475:3T3 Cells; D000199:Actins / Q000378:metabolism; D000818:Animals; D001422:Bacterial Adhesion / Q000502:physiology; D001426:Bacterial Proteins / Q000378:metabolism*; D058947:Bacterial Secretion Systems / Q000502:physiology; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism / Q000382:microbiology; D042783:Endothelial Cells / Q000378:metabolism / Q000382:microbiology*; D004847:Epithelial Cells / Q000378:metabolism / Q000382:microbiology*; D005347:Fibroblasts / Q000378:metabolism / Q000382:microbiology*; D019073:HT29 Cells; D058507:Host Specificity; D006801:Humans; D051379:Mice; D018613:Microscopy, Confocal; D012477:Salmonella enteritidis / Q000378:metabolism / Q000472:pathogenicity* / Q000502:physiology
D000199:Actins; D001426:Bacterial Proteins; D058947:Bacterial Secretion Systems