Full-Length Genome of the Equine Influenza A Virus Subtype H3N8 from 2019 Outbreak in Saudi Arabia.
Authors: Alaql Fanan A, Alhafufi Ali N, Kasem Samy, Alhammad Yousef M O, Albaqshi Hassan, Alyousaf Ameen, Alsubaie Faisal M, Alghamdi Ahmed N, Abdel-Moneim Ahmed S, Alharbi Sulaiman A
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary: Equine Influenza H3N8 Characterisation in Saudi Arabia A 2022 investigation by Alaql and colleagues sequenced the complete genome of equine influenza A virus (EIV) H3N8 strains isolated during a 2019 outbreak in Saudi Arabia, screening 621 horses across 57 facilities for clinical respiratory signs and processing nasopharyngeal swabs via qRT-PCR pooling strategy. Phylogenetic analysis of 39 positive pools revealed that the identified viruses clustered within the Florida sublineage H3N8 clade 1, demonstrating close genetic similarity to concurrent 2019 USA isolates with no evidence of reassortment events. These findings represent among the first detailed genomic characterisation of EIV circulating in the Middle East, establishing a crucial baseline for regional surveillance. The molecular data underscore a significant epidemiological concern: despite commercial vaccine availability, H3N8 continues to spread readily across international borders, suggesting current vaccine formulations may not provide adequate cross-protection against evolving field strains. For equine practitioners, these results reinforce the importance of robust biosecurity protocols, strategic vaccination timing aligned with circulating strains in your geographic region, and reporting of suspected cases to enable real-time genetic tracking that could ultimately inform more effective vaccine strain selection globally.
Read the full abstract on PubMed
Practical Takeaways
- •EIV H3N8 Florida clade continues to circulate and remains a significant respiratory threat to horse populations, with strains similar to those in North America reaching the Middle East
- •Current commercial vaccines may need updating to match circulating strains; veterinarians should monitor global surveillance data for vaccine strain recommendations
- •Rapid screening and genetic sequencing of suspected EIV cases enables early detection of outbreaks and supports international disease monitoring to improve vaccine effectiveness
Key Findings
- •39 out of 57 horse barn pools (68%) tested positive for EIV using qRT-PCR screening
- •Identified virus strains belong to H3N8 clade 1 of the Florida sublineage, closely related to 2019 USA strains
- •No evidence of reassortment detected in the sequenced samples
- •This represents one of the first detailed molecular characterizations of EIV in Saudi Arabia