الفهرس 
Assessment of vector HVT-F vaccine in one-day-old chicks using different vaccination programs and quantification of genome load in feathers and immune organs
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Abstract
The Aim of this study was to evaluate the efficacy of rHVT-F vaccine according to quality control procedure in 1-day old broiler chicks (Identity, Sterility, Titration, Safety and Potency ) and monitoring the comparative efficacy of several vaccination programs by prime-Boost strategy with live and inactivated ND vaccines and detect their effect on humoral and cell mediated immunity(CMI); The protection % post challenge with vvNDV genotype VII at 20 and 28 day old chicks post vaccination and the virus shedding was detected by RT-PCR assay. Recombinant rHVT-F followed by Live vaccine induced higher humoral, CMA, protection % and also reduced virus shedding compared to other program based on using rHVT-F followed by Inactivated or rHV{u2013}F vaccine alone. Quantification of genome load in different immune organs [Bursa of Fabricious (B.F.), Thymus, Cecal tonsils (C.T.), Spleen and Feather follicle epithelium (FFE) ] samples were taken weekly intervals for real time qPCR testing using primer specific to rHVT-F (Biomune) vaccine. Results revealed that positive amplification signals with comparable ct values in B.F. and Thymus samples peaked at 1st week then declined gradually while the signals were detected only at 2nd week in spleen , F.F. showed peak at 2nd week and still detected till 6th w. Easy sampling procedure of F.F.E. make it a sample of choice to study vaccine take. Viral load in lymphoid organ as well as NDV specific humoral immune response is considered a good parameter to be considered in vaccine induced protection.Vaccination quality control and assurance of vaccine uptake are also important for assessment of the efficacy of Recombinant vaccines