Genetic Relatedness of Commercial and Local 793/B-like IBV Vaccines in Iran

Ghalyanchilangeroudi, Arash; Hosseini, Hossein; Ziafati, Zahra; MORSHED, RIMA; Motamed, Najmeh; Jamiri, Fahimeh; Bakhshi, Alireza; Sarmadi, Soroush; Sadighi, Amitis; Rezaee, Seyed Alireza; Mehrnia, Mani; Khakpour, Erfan; Daghayeghi, Ghazal

doi:10.22092/ari.2025.370457.3803

Genetic Relatedness of Commercial and Local 793/B-like IBV Vaccines in Iran

Articles in Press

Document Type : Original Articles

Authors

¹ Department of Microbiology and Immunology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran

² Department of Avian Diseases, Faculty of Veterinary Medicine, Karaj Branch, Islamic Azad University, Karaj, Alborz

³ Agriculture and Veterinary Group, Faculty of encyclopedia, IHCS, Tehran, Iran

⁴ Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension, Karaj, Iran

10.22092/ari.2025.370457.3803

Abstract

Infectious bronchitis virus (IBV), a highly variable member of the Gammacoronavirus genus, continues to pose a significant threat to poultry health and productivity worldwide. Characterized by frequent genetic mutations and recombination events, IBV exhibits considerable antigenic diversity, complicating control efforts and vaccine design. In Iran, 793/B-like IBV strains remain among the most prevalent and problematic genotypes, despite routine vaccination programs implemented across commercial poultry farms. The persistence of these strains raises concerns about vaccine field strain compatibility and the potential for suboptimal protection. This study aimed to investigate the genetic relatedness between newly used 793/B-like IBV vaccine strains and circulating field isolates in Iranian poultry farms. Four vaccine strains were selected for molecular and phylogenetic analysis: three commercial products (POLIMUN IB MULTI BK-07, Avishield IB GI-13, and AVIVAC-IB A/91) and one locally produced strain, 793/B.08IR, developed by the Razi Vaccine and Serum Research Institute. Viral RNA was extracted from each vaccine strain, followed by reverse transcription and amplification of the S1 gene, a key determinant of antigenicity and host immune response. Sequencing data were compared with archived Iranian 793/B-like field isolates and reference strains retrieved from GenBank. Phylogenetic analysis using maximum likelihood methods revealed high sequence similarity (92–100%) among the vaccine strains and historical field isolates. The commercial vaccines BK-07, GI-13, and A/91 exhibited 100% nucleotide identity with one another and clustered closely with the classic 4/91 reference strain, indicating strong genetic conservation. The locally produced Razi strain, 793/B.08IR, showed 100% identity with the Iranian IB88 variant, suggesting its relevance to regional field strains. These findings underscore the genetic similarity between currently used 793/B-like vaccines and circulating IBV genotypes in Iran. However, minor antigenic differences observed in the S1 gene may influence vaccine-induced immunity and warrant further investigation. The study highlights the importance of ongoing molecular surveillance and phylogenetic monitoring to ensure optimal vaccine–strain matching. Such efforts are critical to enhancing vaccine efficacy, reducing viral spread, and minimizing economic losses associated with IBV outbreaks in Iranian poultry operations.

Keywords

Main Subjects