A novel subgroup among genotypes of equine arteritis virus: genetic comparison of 40 strains.

This research looks into the genetic comparison of various strains of equine arteritis virus (EAV) with an emphasis on Hungarian strains, identifying a unique subspecies or grouping among these strains, which had not been previously identified.

Research Parameters and Process

• The researchers focused on the open-reading frame (ORF5) of EAV, specifically looking at partial nucleic sequences spanning from 151 to 668 nucleotides and deducing amino acid sequences of 518 nucleotides.
• They studied 19 Hungarian and one Austrian EAV strains through sequence analysis, and then referenced additional data for 20 more strains (6 North American, 14 European) from GenBank.
• The three variable regions of the Hungarian EAV strains were analyzed, noting that the first had been most affected by point mutations.

The Findings

• The researchers compared the Hungarian strains with other EAV strains from North America and Western Europe, including the Bucyrus reference strain. This was done using the aforementioned genome region.
• The genetic comparison revealed a new genetic subgroup mostly consisting of Hungarian EAV strains.
• When compared to the Bucyrus virus, the Hungarian strains showed sequence divergencies ranging from 81.47 to 90.73% at nucleotide level and from 84.88 to 91.86% at amino acid level.

Epizootiological Implications

• The study found that a significant portion of the EAV strains that existed in Hungary before and around 2000 belonged to a unique cluster (II.D), not indicated in former phylogenetic studies.
• After 2000, new EAV strains emerged in Hungary, some of which caused abortions or neonatal death.
• The previously dominant ‘Hungarian’ EAV genotypes were replaced by these new strains belonging to North American and European subgroups (I.A, I.B, II.A, II.B).
• Infections in Hungary were linked to virus shedder stallions imported to the country after 2000 or that had been infected abroad. One of these stallions became the source of widespread abortions in Hungarian studs.