الفهرس 
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Abstract
One of the major problems of avian infectious bronchitis virus (IBV) is the
frequent emergence of new variants. In the present study, 18 suspected farms
from broiler chicken farms were collected during 2019 to august 2022 from
different governorates in Egypt. These farms showed sinusitis, pharyngitis
and respiratory illness. Eleven suspected farms were positive for IBV with
real time RT-PCR. The samples were homogenised, prepared and inoculated
in specific pathogen free (SPF) embryos for three blind passages and
examined with PCR. The hypervariable region 1 and 2 of spike protein (SP1)
was amplified and sequenced to study the genetic diversity between virus
isolates. Ten isolates were selected and the phylogeny was carried out
between selected isolates and other IBV from the Middle East in gene bank.
The S1 gene was clustered into two major groups , the first group contain
only one virus belong classical strain GI-1 and the second group contain
genotype GI-23 (variant II), with nine viruses occurring in two subgroups,
first subgroup GI-23.2.1, contains 8 viruses and second subgroup contains
one viruse belong to genotype GI-23.2.2