Immunogenicity of Rift Valley Fever Virus ZH 501 used for Vaccine Production in Egypt

摘要

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 INFγ gene expression (24 hours before challenge), then after challenge with 103 TCID50 RVF virus, the INFγ 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 INFγ gene expression increased gradually till reach high level in the 3rd day after challenge.