الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Rift Valley fever (RVF) is an acute disease of sheep, goat and cattle. The disease transmitted to human by mosquitoes causing severe hemorrhagic fever, this study aimed to assessment the molecular characteristics, pathogenicity and immunogenicity of the RVF virus (vaccinal strain). Firstly, the RVF virus was propagated in cell culture then it titrated in both cell culture and mice.One-step RT-PCR technique was applied for detection and quantifying RVF virus genome using TaqMan technology and targeting the nonstructural protein-coding region in S segment. Forty five Three weeks old SPF mice were divided into three groups each group of 15 mice as follow; vaccinated group, control positive and control negative. Blood samples were collected for viable lymphocyte cells count and Interferon γ gene analysis by SYBER Green qRT-PCR at 24hr before challenge and 24hr, 48hr, 72hr after challenge with RVF virus. The control positive group show highly significant increase in viable lymphocytic count at 48 hr post challenge. The qRT-PCR results revealed that vaccinated group showed high level of IFN-γ gene expression (24 hours before challenge), then after challenge with 103 TCID50 RVF virus, the IFN-γ gene expression decreased (24 hr after challenge) then increased gradually till reach high level in the 3rd day after challenge, while in the positive control the IFN-γ gene expression increased gradually till reach high level in the 3rd day after challenge.The RNA of S segment of ZH501vaccinal strain was extracted then it converts to cDNA and ampilified by Conventional PCR. Electrophoresis of PCR product was done. The DNA band was sliced from the gel and purified followed by sequencing. The resultant sequence was aligned with those of previously characterized RVF viruses by Bioedit program which revealed no nucleotide or amino acid substitutions between ZH501vaccinal strain and reference Egyptian strain.