Abstract: |
Avipoxviruses (APVs) are among the most complex viruses that infect a wide range of
birds’ species. The infection by APVs is often associated with breathing and swallowing difficulties,
reduced growth, decreased egg production, and high mortalities in domestic poultry. In the present
study, 200 cutaneous nodular samples were collected from different avian species (chicken, pigeon,
turkey, and canary) suspected to be infected with APVs from Dakahlia Governorate, Egypt. Pooled
samples (n = 40) were prepared and inoculated in embryonated chicken eggs (ECEs). APVs were
then identified by polymerase chain reaction (PCR) and sequence analysis of the APV P4b gene.
Furthermore, the forty strains of APVs were screened for the presence of reticuloendotheliosis virus
(REV)-50LTR in their genomes. Interestingly, the phylogenic tree of the APV P4b gene was separated
into 2 clades: clade 1, in which our fowlpox virus (FWPV), turkeypox virus (TKPV), and canarypox
virus (CNPV) isolates were grouped, along with reference FWPVs and TKPVs retrieved from GenBank,
whereas, in clade2, the pigeonpox virus (PGPV) isolate was grouped with PGPVs retrieved from
GenBank. Likewise, REV-50LTR was amplified from 30 strains isolated from chicken, turkey, and
canary, while PGPV strains were free from REV-50LTR integration. To the best of our knowledge, this
study involved the detection and characterization of REV-50LTR insertions in the APVs field isolates
in Egypt for the first time. Given the above information, further future research seems recommended
to understand the impact of the resulting REV-50LTR insertions on the pathogenesis, virulence, and
inadequate vaccine protection against APVs.
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