TY  - SER
AU  - Abo El-Fadl ,Reham,A.
AU  - Ibrahim,Awad,A.
AU  - Amen,Omer,a.
TI  - Humoral immune response of the low pathogenic avian influenza (H9) vaccines in broilers
KW  - Avian influenza
KW  - Vaccination
KW  - Broilers (Chickens)
N1  - Special issue; Includes bibliographic reference
N2  - Since the first reports of LPAI H9N2 infection in 2011, the Egyptian poultry industry has suffered from unexpected economic losses. 
Hence, a variety of preventative strategies carried out including biosecurity, culling of infected birds and vaccination by inactivated 
vaccines. Unfortunately, immunogenicity of inactivated vaccines are not optimal and low vaccinal coverage so, this study aimed to evaluate 
of humeral immune response against H9N2 inactivated vaccine prepared by using local strain (A/Ck/EG/114940v/NLQP/11) in chickens but 
do not measure efficacy of vaccine which should depend on national basis and monitor the waning of MDAs by using HI test. A total of 
150 one day old Arbor Acres chicks which were possessed high level of MDAs and divided into 3 groups A, B and C, each one contained 50 chicks. 
Group A, was non-vaccinated group, while group B, vaccinated at 1day of age and group C, vaccinated at 7 days, sera were collected weekly 
and examined immediately by HI test using homologues antigen. The administration of H9N2 at the 1st or 7th day, the immune response mainly 
related to MDAs in the 1st and 2ndwk of age the titer increased at 3rdwk. Vaccination of the chicks is necessary and should begin at 7 days 
of age that reaching a beak with mean HI titer (6.2log2) at 5thwk and then decline to 4.8log2 at 7thwk of age based on a protective HI titer 
of H9N2 is ? 4 log2.Vaccination at early days of age give inadequate immune response reaching a maximum with mean HI titer (5.5log2) at 4thwk 
and then decline to 4.5log2 at 6thwk post vaccination. Chicks possessed high level of maternal antibodies at hatching with mean HI titer 
(8.0 log2) but this level declined linearly to reach (4.6 log2) at 2ndwk. At the 3rdwk MDAs level become very low and reach to un-protective 
titer (2.5 log2) and completely disappeared at 6thwk of age, so MDAs can protect chicks at first 10-14 days of age and do not interfere with 
inactivated vaccine

UR  - http://nile.enal.sci.eg/EALE/2019/AVMJ/6519/0/49.pdf
ER  -