AvrA effector protein of Salmonella enterica serovar Enteritidis is expressed and translocated in mesenteric lymph nodes at late stages of infection in mice.

MÓNICA N. GIACOMODONATO, MARIÁNGELES NOTO LLANA, MARÍA DEL ROSARIO AYA CASTAÑEDA, FERNANDA R. BUZZOLA, SEBASTIAN H. SARNACKI, MARIA C. CERQUETTI.

MICROBIOLOGY-UK

SOC GENERAL MICROBIOLOGY

Lugar: London; Año: 2014 vol. 160 p. 1191 - 1199

1350-0872

Salmonellosis is a major health problem worldwide. Salmonella enterica serovar Enteritidis (S.Enteritidis) has been a primary cause of Salmonella outbreaks in many countries. AvrA is an SPI-1effector protein involved in the enteritis pathway, with critical roles in inhibiting inflammation andapoptosis. In this work, we constructed an AvrA-FLAG-tagged strain of S. Enteritidis to analysethe expression profile of AvrA in vitro, in cell culture and in vivo. AvrA expression and secretionwere observed in vitro under culture conditions that mimicked intestinal and intracellularenvironments. In agreement, bacteria isolated from infected cell monolayers expressed andtranslocated AvrA for at least 24 h post-inoculation. For in vivo experiments, BALB/c mice wereinoculated by the natural route of infection with the AvrA-FLAG strain. Infecting bacteria andinfected cells were recovered from mesenteric lymph nodes (MLN). Our results showed that AvrAcontinues to be synthesized in vivo up to day 8 post-inoculation. Moreover, AvrA translocationwas detected in the cytosol of cells isolated from MLN 8 days after infection. Interestingly, weobserved that AvrA is secreted by both type three secretion system (T3SS)-1 and T3SS-2. Insummary, these findings indicate that AvrA expression is not constrained to the initial host?bacteria encounter in the intestinal environment as defined previously. The AvrA effector mayparticipate also in systemic S. Enteritidis infection.