VARIABILITY IN THE RESISTANCE OF 4 CHICKEN LINES TO EXPERIMENTAL INTRAVENOUS INFECTION WITH SALMONELLA-ENTERITIDIS PHAGE TYPE-4

The capacity of four chicken lines (Y11, L2, B13, PA12) to control Sal monella enteritidis (SE) phage type 4 (PT4) systemic colonization was investigated. Thirteen-week-old chickens were intravenously inoculated with 10(6) SE colony-forming units, and the levels of SE colonization were determined at various time intervals after inoculation in liver, spleen, genital organs, and ceca. The course of SE infection showed a rapid contamination of liver, spleen, and genital organs, whereas the ceca were infected later. A significant (P < 0.001) effect of the chi cken line on levels of SE was detected on day 3 postinoculation (PI) i n liver and ceca, on day 10 PI in ceca, and on day 15 PI in spleen. Be cause an early control of systemic Salmonella infection by the ItylNra mp1 gene has been demonstrated in mice, we aimed to study the early re sistance of chickens to SE. As a consequence, we then focused our stud y on the between- and within-line variabilities of SE levels on day 3 PI. According to the SE levels in liver on day 3 PI, the chicken lines could be classified as susceptible (Y11 and L2) or resistant (PA12 an d B13). This early variability was explored in resistant B13 and susce ptible L2 lines. Differences between these two lines were confirmed in liver but not in ceca. A large within-line variability was observed i n all organs of these two lines. The genetic origin of this variabilit y will have to be determined as a prerequisite to an eventual selectio n.