TABLE 3.

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

GroupPrimary immunizationaSecondary immunizationOocyst challengebWeight gain (g) (mean ± SEM)cFeed conversion ratioc
G1BSGBSGNo141 ± 7 Ad2.93 A
G2χ8879(pYA3870) (T3SS-vector control)χ9242(pYA3493) (T2SS-vector control)Yes127 ± 2 B2.94 A
G3χ8879(pYA3658) (T3SS-EAMZ250)χ8879(pYA4157) (T3SS-SO7)Yes140 ± 3 A2.75 A
G4χ8879(pYA3658) (T3SS-EAMZ250)χ9242(pYA4184) (T2SS-SO7)Yes136 ± 5 AB2.76 A
G5χ8879(pYA4157) (T3SS-SO7)χ9242(pYA4184) (T2SS-SO7)Yes132 ± 1 AB2.71 A
G6χ9242(pYA4184) (T2SS-SO7)χ9242(pYA4184) (T2SS-SO7)Yes135 ± 1 AB2.85 A
  • 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. acervulina oocysts.

  • c Right before the oocyst challenge and on day 6 postchallenge, the 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).