Detection and identification of infectious bronchitis virus by RT-PCR in Iran

Morphological, serological, molecular detection, and phylogenetic analysis of Trypanosoma evansi in horses of different regions in Iran

Trypanosoma evansi, the causative agent of "surra" is enzootic in Iran. The current study aimed to detect T. evansi in horses from different regions of Iran using morphological, serological, and molecular methods. In 2021, 400 blood samples were collected from horses in eight regions. Eighty horses showed clinical signs such as cachexia (n = 64), fever (n = 36), foot edema (n = 40), and abdominal edema (n = 32), and 320 horses appeared healthy. All samples from the studied regions were evaluated for the presence of trypanosomes using direct analysis of blood smears, mercuric chloride, and PCR-based tests. In total, 12% (95% CI: ± 3.1%), 21% (95% CI: ± 3.9%), and 21% (84) of animals were positive for Trypanosoma in microscopic, serologic, and molecular analyses, respectively. All animals positive for SSU rDNA PCR were from Qom, Semnan, and Golestan regions. Further molecular analyses on 84 PCR-positive horses revealed that 29 horses scored positive in PCR using primers of trypanozoon species and 5 scored positive in PCR using primers of Trypanosoma evansi type A. All samples (n = 5) were from Qom region. The 205-bp fragments of T. evansi RoTat 1.2VSG (accession numbers: ON017789-93) analyzed and compared to other isolates sequence from GenBank BLAST search. It has close similarities with isolates from Pakistan, Egypt, Malaysia, Kenya, and India. Data herein demonstrated that horses from Iran were at high risk of T. evansi infection. Comprehensive control programs, such as those based on the application of repellants and traps, and also, compliance with quarantine standards are recommended for minimizing the risk of the infection.

Molecular characterization of infectious bronchitis virus based on RNA-dependent RNA polymerase gene

Extensive rate of variations in the S1 gene (spike glycoprotein subunit gene) of infectious bronchitis virus (IBV) causes challenges for clinicians in counting variants for differentiation of infected from vaccinated birds and addressing the variants of unknown significance. This study investigated the possibility of using an RNA‐dependent RNA polymerase gene (RdRp) as a target for molecular characterization of IBV strains in Iran. Trachea samples were collected from commercial broiler flocks (n = 52) showing respiratory syndrome. Specific PCR primers were designed for a variable region located in the RdRp gene flanked by highly conserved regions. Reverse transcriptase PCR followed by sequence analysis identified eight IBV variants, with an overall prevalence of 44.2%. Deduced nucleotide and amino acid sequences were compared with published sequences for IBV strains. Because of the long‐distance similarities, the field samples could be discriminated from vaccine strains. Phylogenetic analysis of RdRp gene sequences resulted in clustering of the IBV strains related to each area. Using RdRp as a genetic marker eliminates the challenges arising from the enormous variations that make it difficult to discriminate between field and vaccine strains as well as affiliate certain variants to various geographical areas.