Broiler breeder Lohmann chickens aged 39 weeks received 3 doses each 0.2 ml of the inactivated oil emulsion AI- H9N2 vaccine, at the 2nd, 7th and 15th weeks of age by subcutaneous injection. The individual HI values of the tested samples were homogenous as their SD values were lower. All breeder and progeny sera were positive (100- 66.7%) at weeks 40- 46 weeks of age. Correlation between parents and progeny HI antibody levels was 0.95. Progeny/Parents HI antibodies percentage were ranged from 54.9 to 65.2%. Correlation between parents and progeny ELISA and HI antibody levels were 0.91 and 0.60- 0.65; respectively. The detected HI antibody titres at the 3rd day of age were slightly increased than that of the 1st day titres followed by gradual decrease to be apparently negative at the 12th -21st day of age in comparison to the original levels. The tested groups for Antibodies to H9 by ELISA test were still detected to 21- 27 days of age of progeny. The half-life time of maternal antibodies expressed as loss of one HI log 2 between groups was ranged from 3.3- 7.2 days; with average 5.1- 5.6 days. Half life time by ELISA titre was in average of 8.9 days. Correlations between HI and ELISA ranged from 0.83-0.94. We concluded that both HI and ELISA tests are of the same value in detection of AI antibodies and first vaccination of broiler chicks with maternal antibodies against AI H9N2 must be done after the 6th day of age.

Glycoprotein 5 (GP5) of porcine reproductive and respiratory syndrome virus (PRRSV) has been studied extensively as a target for vaccine development. This study evaluated the serodiagnostic application of PRRSV GP5 by enzyme-linked immunosorbent assay (ELISA). Two immunodominant peptides (VR #1 and VR #2) and two neutralizing ectodomain-containing peptides (Ecto #1 and Ecto #2), as well as recombinant GP5 (rGP5) as a control, were prepared. Serum from unvaccinated pigs was screened for the antibodies that bind to these peptide and protein antigens. The results were compared with those from a commercially available diagnostic ELISA kit (HerdChek), which uses the nucleocapsid (N) protein as an antigen. Only VR #1+#2 showed a result statistically similar to that of N protein. Ecto #1 and Ecto #2 had a lower sensitivity than VR #1+#2 and rGP5. The peptides and rGP5 showed significant associations with the N protein (P < 0.05 or 0.01), which suggests that GP5 may also be a candidate serodiagnostic antigen. Since antibodies against GP5 persist much longer than those against the N protein, GP5 itself and some of its fragments are thought to be good targets for serodiagnosis. In addition, the presence of antibodies against the PRRSV structural antigens showed significant antigen-dependent differences.

The humoral and cell-mediated immune (CMI) response to 2 commercial killed Salmonella Enteritidis (SE) vaccines (Layermune and MBL SE4C) was evaluated in laying hens. Layers were distributed in 2 experimental groups. The first received a single immunization at 16 wk of age, while the second experimental group was immunized at 12 wk of age and again at 18 wk of age. Serum immunoglobulin (Ig)G antibodies were measured using a commercial SE ELISA kit and showed persistent levels from 3 to 32 and 34 wk post-vaccination. The vaccination protocol using 2 immunizations showed a higher seroconversion level than the single vaccination. However, our results for bacterial intracellular survival indicated that IgG titers were not linked with bacterial killing. Local IgA production was measured in the intestines and oviducts with an in-house SE whole cell antigen ELISA. Only the MBL SE4C vaccine elicited IgA antibody production when tested on intestine and oviduct mucosal secretions, 3-weeks post-vaccination in both immunization protocol groups. To evaluate the CMI response, the splenic T-cells and B-cells populations were analyzed using flow cytometry. The CD3/B-cell ratio decreased 3 wk after the second immunization in the twice vaccinated Layermune group due to an increase in B-cells.