Made available in DSpace on 2014-12-03T13:08:49Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-01-01Bitstream added on 2014-12-03T13:23:22Z : No. of bitstreams: 1 WOS000336293900001.pdf: 4743787 bytes, checksum: 8231a4a3d8ac0fba9e21d848451bf982 (MD5) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Atypical enteropathogenic Escherichia coli (aEPEC) inject various effectors into intestinal cells through a type three secretion system (T3SS), causing attaching and effacing (A/E) lesions. We investigated the role of T3SS in the ability of the aEPEC 1711-4 strain to interact with enterocytes in vitro (Caco-2 cells) and in vivo (rabbit ileal loops) and to translocate the rat intestinal mucosa in vivo. A T3SS isogenic mutant strain was constructed, which showed marked reduction in the ability to associate and invade but not to persist inside Caco-2 cells. After rabbit infection, only aEPEC 1711-4 was detected inside enterocytes at 8 and 24 hours pointing to a T3SS-dependent invasive potential in vivo. In contrast to aEPEC 1711-4, the T3SS-deficient strain no longer produced A/E lesions or induced macrophage infiltration. We also demonstrated that the ability of aEPEC 1711-4 to translocate through mesenteric lymph nodes to spleen and liver in a rat model depends on a functional T3SS, since a decreased number of T3SS mutant bacteria were recovered from extraintestinal sites. These findings indicate that the full virulence potential of aEPEC 1711-4 depends on a functional T3SS, which contributes to efficient adhesion/invasion in vitro and in vivo and to bacterial translocation to extraintestinal sites. Univ Fed Sao Paulo, Escola Paulista Med, Dept Microbiol Imunol & Parasitol, BR-04023062 Sao Paulo, Brazil Univ Fed Sao Paulo, Escola Paulista Med, Dept Cirurgia, BR-04039032 Sao Paulo, Brazil Univ Sao Paulo, Fac Med Vet, Dept Ornitopatol, BR-05508900 Sao Paulo, Brazil Univ Estadual Paulista, Inst Biociencias, Dept Microbiol & Imunol, BR-18618970 Sao Paulo, Brazil Fleury Med & Saude, BR-04344903 Sao Paulo, Brazil Univ Fed Sao Paulo, Escola Paulista Med, Ctr Microscopia Eletron, BR-04023062 Sao Paulo, Brazil Univ Estadual Paulista, Inst Biociencias, Dept Microbiol & Imunol, BR-18618970 Sao Paulo, Brazil FAPESP: 08/53812-4 FAPESP: 11/12664-5 CNPq: 304453/2011-0 CNPq: 150833/2012-1