TABLE 4.

Immunization of chickens with RASV strains and E. tenella oocyst challenge

GroupPrimary immunizationaSecondary immunizationOocyst challengebWeight gain (mean ± SEM)cFeed conversion ratioc
G1BSGBSGNo141 ± 7 Ad2.93 C
G2χ8879(pYA3870) (T3SS-vector control)χ9242(pYA3493) (T2SS-vector control)Yes92 ± 11 D4.12 A
G3χ8879(pYA4157) (T3SS-SO7)χ8879(pYA4157) (T3SS-SO7)Yes102 ± 4 BC3.71 AB
G4χ8879(pYA4157) (T3SS-SO7)χ9242(pYA4184) (T2SS-SO7)Yes116 ± 12 BC3.12 BC
G5χ9242(pYA4184) (T2SS-SO7)χ9242(pYA4184) (T2SS-SO7)Yes124 ± 6 AB3.14 BC
  • a Chickens received a primary immunization when they were 1 week old and a secondary immunization 1 week later. Strains χ8879 (ΔsptP1033::xylE ΔasdA16 ΔphoP233) and χ9242 (ΔphoP233 ΔasdA16 ΔaraBAD23 ΔrelA198::araC PBAD lacI TT) were used for immunization.

  • b Three weeks after the secondary immunization, chickens in groups G2 to G6 were inoculated with 105 E. tenella oocysts.

  • c Right before the oocyst challenge and on day 6 postchallenge, body weights were recorded, and the weight gain and feed conversion ratio (grams of feed consumed per gram of body weight gained) were calculated.

  • d Means that are not followed by the same letter are significantly different (P < 0.05).