Re-Emergence of Very Virulent IBDV in Egypt
Re-Emergence of Very Virulent IBDV in Egypt
Ashraf M. Metwally*, Ausama A. Yousif*k , Iman B. Walaa A. Attia M. Samy * , and Ismail M. Reda *
ABSTRACT
Infectious bursal disease (IBD) serotype 1 viruses continue to cause major economic losses in the Egyptian poultry industry despite the implementation of intensive vaccination programs. A recent increase in IBD related mortality in vaccinated farms prompted this investigation into the genetic character of the circulating IBD virus (IBDV). Bursa and proventriculus samples were RT-PCR tested using novel primers flanking VP2 region coding the two major and two minor hydrophilic peaks. IBDV was detected in tested samples. Phylogenetic analysis of the sequenced PCR product and deduced amino acid sequences of IBDV Giza2008 VP2 demonstrated the continued circulation of very virulent IBDV (vvIBDV). The mutations reported in Giza2008 demonstrate that Egyptian field viruses are isolating from their European ancestors. Some of the aa mutations have lead to a change in some of the exposed regions of the viral protein. Our findings explain the continued presence of vvIBDV in intensively vaccinated flocks.
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