Figure 1.
Validation of rMDV-HA by PCR amplifications of MDV US2 gene region and HA open reading frame.
(M) DNA ladder; (R) the rMDV-HA infected CEF cells: the fragment of US2 region that covered the HA expression cassette and gpt selective marker, 4572 bp; the fragment of HA open reading frame, 1712bp. (WT) the MDV 814-infected CEF cells, the fragment of US2 region, 1180 bp; (NC) negative control.
Figure 2.
Growth curves (one-step growth kinetics) of rMDV-HA, MDV 814 and rHVT-HA.
After inoculation of chickens with 100 PFU of each virus, virus titers were determined at different times and steadily increased from 48 to 96 h post-infection until maximal titers were reached. The data of the growth curve of rHVT-HA were cited from reference [18]. Stars indicate that the differences were significant between the groups (P<0.05).
Figure 3.
Immunofluorescence and Western blot analyses of recombinant HA protein expressed in rMDV-HA infected CEF cells.
AIV-specific chicken serum antibodies bound to the rMDV-HA infected CEF cells (A) by indirect immunofluorescence, but not to the CEF cells infected with MDV 814 (B) 72 h post-infection. CEF cells infected with rMDV-HA and non-infected cells probed with an AIV-specific chicken serum and IRDye™ 800-labeled polyclonal rabbit anti-chicken IgG (1∶4000). HA-specific bands corresponding to the cleaved HA1 and HA2 were detected in preparations of rMDV- HA-infected cells by Western blot, but not in MDV 814 infected cells (C).
Figure 4.
Comparison of viremia levels between rMDV-HA, MDV 814 and rHVT-HA.
One-day old chicks were vaccinated with either rMDV-HA or MDV 814, and bled on 7, 14, 21 and 28 days post infection for determination of viremia. The data of the viremia level of rHVT-HA were cited from reference [18]. Stars indicate that the differences were significant between the groups (P<0.05).
Figure 5.
Protection of vaccinated chickens against virulent MDV challenge.
Cumulative survival of chickens from unvaccinated chickens or the chickens vaccinated with rMDV-HA, rHVT-HA or MDV 814 during the 60 day evaluation period after chickens were challenged with virulent MDV strain J-1.
Table 1.
Protective efficacy of vaccines against virulent MDV challenge.
Table 2.
Results of HI test of sera from chickens vaccinated with recombinant or MDV 814 vaccines.
Table 3.
Protective efficacy of vaccines against HPAIV H5 challenge in chickens.