Molecular Characterization of the Major Open Reading Frames (ORFs) and Enhancer Elements From Four Geographically Distinct North American Equine Infectious Anemia Virus (EIAV) Isolates.
Authors: Cook Sheila J, Li Ganwu, Zheng Ying, Willand Zachary A, Issel Charles J, Cook R Frank
Journal: Journal of equine veterinary science
Summary
# Editorial Summary: Genetic Diversity of North American EIAV Isolates and Implications for Diagnostics and Vaccines Equine infectious anemia virus exhibits far greater molecular diversity within North America than previously appreciated, with Cook and colleagues demonstrating nucleotide sequence identity between regional isolates ranging from only 75.4–84.6%. Using long-range PCR combined with next-generation sequencing, the research team characterised four geographically distinct North American EIAV strains (from Pennsylvania, Tennessee, North Carolina, and Florida) and compared them against established field and laboratory strains from Europe and Asia, finding that whilst all New World isolates clustered into a single phylogenetic group consistent with historical European introduction, their genetic divergence approaches that between North American and Asian strains. The substantial variation identified across major open reading frames and enhancer elements within the long terminal repeats has critical implications for both vaccine development and diagnostic test design, as current approaches may fail to account for this regional genetic heterogeneity. For equine practitioners, these findings underscore that EIAV should be considered a genetically complex pathogen at the continental level, warranting caution when assuming that diagnostic platforms or immunological strategies validated against one isolate will perform equally across different geographic populations.
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Practical Takeaways
- •EIAV vaccine and diagnostic development must account for significant genetic variation among North American isolates, suggesting single-strain approaches may have limited effectiveness across different regions
- •The substantial genetic diversity within geographically distinct North American EIAV isolates supports continued surveillance and molecular characterization to inform region-specific diagnostic and preventive strategies
Key Findings
- •Four North American EIAV isolates (Pennsylvania, Tennessee, North Carolina, Florida) showed nucleotide sequence identity ranging from 77.6% to 84.6% with each other and known strains
- •All North American EIAV isolates formed a single monophyletic group distinct from Asian isolates, consistent with historical reintroduction of equids by European settlers
- •Substantial genetic diversity exists within North American EIAV isolates despite their phylogenetic clustering, with some North American strains showing greater similarity to Asian strains than to each other