Genotyping of OLA-DRB1 in Fashandi Sheep for effective Vaccination and Disease Management Strategies

Ranjbar, Mohammad Mehdi; Cheraghi, Tayebeh; Momeni, Zohre; Asli, Esmaeil

doi:10.22092/ari.2026.371174.3917

Genotyping of OLA-DRB1 in Fashandi Sheep for effective Vaccination and Disease Management Strategies

Articles in Press

Document Type : Original Articles

Authors

¹ Razi vaccine and Sera institute

² Razi Vaccine and Serum Research Institute (RVSRI), Agricultural Research, Education, and Extension Organization (AREEO), Karaj, Iran

³ Islamic Azad University, Karaj Branch (KIAU), Karaj, Alborz, Iran

10.22092/ari.2026.371174.3917

Abstract

Introduction: The major histocompatibility complex (MHC) in large animals, known as Ovine Leukocyte Antigen (OLA) in sheep, is crucial for understanding genetic diversity, disease susceptibility, reproductive traits, and vaccine responsiveness. This sequenced OLA-DRB gene Fashandi sheep breeds to explore their role in disease resistance and vaccine response. Method and material:Fifty blood samples were collected from Fashandi breed using EDTA tubes. Forty samples were stored at −20°C for DNA extraction using the i-genomic Blood DNA Extraction Mini Kit. Amplified PCR products were electrophoresed and sequenced. BLASTn (NCBI) was used for sequence identification. DRB sequences were aligned and compared with reference sequences from the Immuno Poly morphism Database (IPD) using BioEdit software. Allelic/genotypic frequencies were determined via direct counting, and genetic diversity metrics (homozygosity, heterozygosity, allele number) were calculated using Levene’s test and Nei’s formulas via PopGene 1.32 and GenAleXA. For bioinformatics, sequences were aligned with ClustalX and analyzed using BioEdit and CLC Sequence Viewer. Shannon entropy measured amino acid variability, and phylogenetic trees were constructed with MEGA5.3 using neighbor joining. Results: Eight Ovar-DRB1 exon 2 alleles were identified: *08, *19, *07, *24, *30, *16, *03, and *14. The most frequent were *08 (30%) and *07 (25%), while *30 and *03 were least common (5%). The predominant genotypes were *08/*08 and *07/*07 (each 20%). Homozygosity and heterozygosity were equal at 50%. Discussion: The presence of multiple alleles suggests genetic diversity influencing disease susceptibility and resistance and also vaccine response in Iranian Fashandi sheep breeds. Understanding these genetic markers can guide better breeding, vaccination and disease management strategies.

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