Molecular Characterization of Recent Isolates of Bef Virus in Egypt

Abstract

The present work was conducted to identify and characterize recent isolate of bovine ephemeral fever virus (BEFV) in Egypt. 103 serum samples were obtained from 1600 vaccinated animals in El-Salhia dairy farm during the period of July to August 2015. The 103 animals were found to have non-protective low titers of BEF antibodies (≤2-8) as tested by serum neutralization test (SNT), showing BEF signs (fever; harried respiration; lameness and recumbency). Three buffy coat and five blood plasma samples from the 103 suspected infected dairy cattle were collected. Trials of virus isolation in baby mice brain and BHK 21 cell culture revealed that three samples of buffy coat and five blood plasma samples were suspected to contain BEFV. Virus identification using virus neutralization tests (VNT) and direct fluorescent antibody technique (FAT) confirmed the presence of BEFV. In addition, PCR, sequencing analysis and phylogenetic tree showed that the obtained isolate is closely related to Egypt-2005 strain. These findings indicated that the locally produced vaccine is highly immunogenic inducing a protection rate of 93.6%. Appearance of disease signs in cattle with low immune levels could be due to parturition and high lactation stress factors in addition to suspected other infection leading to poor immune response (immune suppression) to the vaccine.

Detection of Bovine Ephemeral Fever Virus (BEFV) in Three Egyptian Governorates During Summer of 2019.

“…The BEF virus can often be identified by viral isolation, serological and molecular tools conducted on a blood sample taken from animals in the acute febrile stage of the disease (OIE, 2008). Our obtained results of SNT which was carried out on serum samples collected from clinically infected cattle showed that all of them had very low titers of BEFV serum neutralizing antibody less than 32, which indicated that such were fully susceptible to the infection with BEF virus(Albehwar et al, 2018 ). The protective level of BEFV antibodies should not be less than 32 to achieve full protection of animals as demonstrated by(Daoud et al 2001; Salah, 2006; Aziz-Boaron et al, 2014).…”

“…Serum neutralization test (SNT) was carried out on serum samples collected from diseased cattle showed that all of them had very low titers of BEF serum neutralizing antibody titers as tabulated in Table (1) indicated that such were fully susceptible to BEF virus infection.…”