M. H. Fallah Mehrabadi - Department of Poultry Diseases, of Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Tehran, Iran
A. Ghalyanchilangeroudi - Department of Microbiology and Immunology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
S. Charkhkar - Department of Clinical Sciences, Faculty of Veterinary Medicine, Islamic Azad University, Tehran, Iran
H. Hosseini - Department of Clinical Sciences, Faculty of Veterinary Medicine, Islamic Azad University, Karaj Branch, Alborz, Iran
T. Zabihipetroudi - Department of Microbiology and Immunology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
A. Shayganmehr - Department of Microbiology and Immunology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
R. Esmaeelzadeh - Department of Microbiology and Immunology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
L. Aghaeean - Department of Microbiology and Immunology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran

Fowlpox is an economically significant viral disease in poultry, characterized by two forms of clinical signs, including cutaneous and diphtheritic lesions. This infection can have several adverse effects on flock performance, such as a reduction in egg production and growth and an increase in mortality. In winter ۲۰۱۸, an infection suspected to fowlpox was reported from a Hy-line W-۳۶ laying farm in Isfahan province, Iran. The birds were ۳۸ weeks of age and showed obvious diphtheritic signs in mucous membranes with increased mortality and reduced egg production. In total, ۲۰ samples were collected from diphtheritic lesions (Trachea and Esophagus) of infected birds. The Polymerase Chain Reaction method was used to amplify a ۵۷۸ bp fragment of the poxvirus ۴b core protein gene. Phylogenetic relationships of avian poxviruses are usually analyzed using the ۴b core protein-coding gene sequences with molecular weights of ۷۵.۲ kDa. The major elements had the fowlpox genome, and sequencing was performed for one isolate as representative. The nucleotide sequence result showed that this isolate (FP\UT-POX-۲۰۱۸) had a similarity rate of ۹۹.۵۳% with the previous Iranian fowlpox isolate (FP\GHPCRLAB.۳) sequenced in the GenBank.Moreover, there was a ۱۰۰% similarity among the current isolate nucleotide sequence, FP/NobilisVarioleW, and FP/FPV-VR۲۵۰. The derived phylogenetic tree showed that these isolates were clustered in A۱ subclades.  Therefore, Iranian isolates of fowlpox virus have remained in the same subclade of phylogenetic classification (subclade A۱), and they show high genomic similarity with previous isolates of Iran. Veterinarians and farmers must not underestimate fowlpox. However, they should consider the importance of vaccination against this disease like any other disease care.

Fowlpox, Iran, Laying flock, PCR, Phylogenetic analysis