Table 4.
Seropositivity for anti-H5 HA antibodies in layer chickens vaccinated with alum-adjuvanted rH5-E. coli.
| Group | Positivity in tests [%] | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 4a or 6b weeks post-prime | 1 week post-boost | 2 weeks post-boost | ||||||||||
| iELISA | FluAC | FluAC | HI | iELISA | FluAC | FluAC | HI | iELISA | FluAC | FluAC | HI | |
| + | + | +/- | + | + | + | +/- | + | + | + | +/- | + | |
| L-25/4 x | 100 ax | 0 ax | 0 ax | 0 a∧ | 100 x | 100 x | 0 x | 90 x | 100 x | 89 ∧ | 0 ∧ | 70 x |
| L-15/4 x | 60 ax | 0 ax | 0 ax | 0 ax | 100 x | 70 x | 0 x | 80 x | 100 x | 63 # | 0 # | 60 x |
| L-10/4 x | 90 ax | 0 ax | 0 ax | 0 a∧ | 100 x | 90 x | 0 x | 89 ∧ | 100 x | 90 x | 0 x | 80 x |
| L-5/4 x | 90 ax | 0 ax | 0 ax | 0 a∧ | 100 x | 50 x | 0 x | 89 ∧ | 100 ∧ | 40 x | 10 x | 56 ∧ |
| Mean ± SD (n = 4) | 85 ± 17 | 0 ± 0 | 0 ± 0 | 0 ± 0 | 100 ± 0 | 78 ± 22 | 0 ± 0 | 87 ± 5 | 100 ± 0 | 70 ± 24 | 3 ± 5 | 66 ± 11 |
| L-25/6 x | 25 b# | 0 b# | 0 b# | 0 b* | 100 x | 90 x | 0 x | 100 x | 100 ∧ | 80 x | 0 x | 89 ∧ |
| L-15/6 x | 0 b∧ | 0 bx | 0 bx | 10 bx | 100 x | 70 x | 0 x | 100 ∧ | 100 x | 70 x | 0 x | 100 ∧ |
| L-10/6 x | 30 bx | 0 bx | 0 bx | 0 bx | 100 x | 80 x | 0 x | 100 x | 100 x | 80 x | 0 x | 70 x |
| L-5/6 x | 33 b∧ | 0 b∧ | 0 b∧ | 11 b∧ | 100 x | 60 x | 0 x | 80 x | 100 x | 60 x | 0 x | 80 x |
| Mean ± SD (n = 4) | 22 ± 15 | 0 ± 0 | 0 ± 0 | 5 ± 6 | 100 ± 0 | 75 ± 13 | 0 ± 0 | 95 ± 10 | 100 ± 0 | 73 ± 10 | 0 ± 0 | 85 ± 13 |
| Mean ± SD (n = 8) | 100 ± 0 | 76 ± 17 | 0 ± 0 | 91 ± 8 | 100 ± 0 | 71 ± 17 | 1 ± 4 | 76 ±15 | ||||
Eight groups of 3-week-old layer chickens in Exp 2 were vaccinated twice at 4- and 6-week intervals, with 25 μg, 15 μg, 10 μg, or 5 μg of rH5-E. coli and aluminum hydroxide (alum) adjuvant. The test vaccine groups were denoted according to the chicken type (L, layer), the tested antigen dose in μg (25, 15, 10, and 5), and the time interval between doses in weeks (4 or 6). Post-vaccination sera were analyzed for the presence of anti-H5 HA antibodies using the indirect and competitive ELISAs, H5 iELISA and FluAC H5, respectively, and a hemagglutination inhibition (HI) assay with H5N2 low-pathogenic (LP) AIV. Tests were performed and interpreted as described in the Materials and Methods section. Data are presented as the percentage of chickens positive (+) in iELISA and HI tests, and positive (+) or doubtful (+/–) in the FluAC test at the indicated sampling time points. The x, ∧, #, and * symbols following the seropositivity percentages denote that 10, 9, 8, and 7 chickens were tested, respectively, in the group comprising 10 (x) chickens.