الفهرس 
cover englishOnly 14 pages are availabe for public view
 |  | from | 204 |  |  |
| | | from | 204 | | |
Abstract
Vaccination is the main preventive measure against Newcastle Disease
virus (NDV) infections and infectious bronchitis virus (IBV) infections.
Vaccination can partially protect against IBV because of the continuous
emergence of variant strains. The aim of the current study is to prepare and
evaluate acombined multivalent inactivated vaccine candidate composed
of NDV (genotype VII), and two IBV lineages (M41; GI-lineage) and
(VarII; GI-23 lineage) in a Montanide ISA-71 oil adjuvant . The results
revealed that the prepared vaccine candidate was sterile, safe, and potent .
The result of potency test showed the ability of the prepared to stimulate
the production of specific antibodies against IBV and NDV starting from 1-
week post vaccination (WPV). The maximum levels of specific IBV
ELISA antibody titers (2926) were observed at the sixth week post
vaccination. HI antibodies against IBV reached their peak at 5th WPV
(9.2 log2) while HI antibodies against NDV reached its peak at 4 WPV
(9.5 log2). Vaccinated chickens showed 100% protection against challenge
with virulent NDV, and variant IBV strains with complete absence of
clinical signs and postmortem lesions compared to challenged non
vaccinated groups. Our results revealed that the prepared vaccine candidate
in this study is able to elicit good immune response, eliminate viral
shedding, and provide complete protection against challenge. Meanwhile, it
is better to control both IBV and NDV outbreaks in a single shot
consequently that will save time, effort and reduce stress during chicken
.vaccination