الفهرس 
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Abstract
In the first part of the current study, we performed genetic and antigenic
characterization of the Egyptian H5N1 viruses. Phylogenetic analysis of
the available HA sequences revealed the presence of two main
sublineages; the classic 2.2.1 and the variant 2.2.1.1. Sequence analysis
revealed that the variant viruses 28 amino acid mutations in the
previously reported antigenic sites and high evolution rate which may be
due to selective pressure from vaccination and/or natural infection.
Antigenic relatedness of the 459-3/06 isolate with other isolates ranged
from 30.7% to 79.1% indicating significant antigenic drift of the H5N1
viruses from the ancestral strains. The antigenic relatedness between C2
and V2 clusters ranged from 28.9% to 68% supporting the need for
vaccine seed strains from both clusters. Interestingly, A/CK/EG/1709-
6/2008 H5N1 strain showed a broad cross reactivity against viruses in
different H5N1 demonstrating a potential candidate as a vaccine strain.
In the second part of the current study, we used the in vitro
mutagenesis and reverse genetics to develop broad reactive H5N1
vaccine. The reverse genetically created virus containing modified HA of
variant strain(A/chicken/Egypt/1063/2010) with five amino acid mutations (G140R, Y144F, I190L, K192Q, D43N) in the HA gene showed broadened reactivity. In addition, a single amino acid substitution (N165H), which removes potential glycosylation site at the HA globular head of classic strains (A/chicken/Egypt/102d/2010 and
A/chicken/Egypt/527/2012) broaden the reactivity to different antisera
tested demonstrating a potential candidates as a vaccine strains. We found that the conserved mutations I190L and K192Q in the variant V2 viruses
had minor impact on the antigenicity profile.