Geographic structuring of global EIAV isolates: a single origin for New World strains?

This study investigated the geographic structuring of global Equine infectious anaemia virus (EIAV) isolates and suggested that New World strains likely originated from a single event during the 15th century when horses were reintroduced to the Americas by European colonists.

Background

• Equine infectious anaemia virus (EIAV) is a type of retrovirus that, like other lentiviruses, tends to undergo significant antigenic variation. This means the virus has the ability to alter the proteins on its surface, helping it to evade the host’s immune response.
• The motivation behind this research is to understand and map the distribution patterns and the evolutionary history of EIAV in a geographical context.

Methodology

• The researchers used an extensive phylogenetic analysis. Phylogenetics is a branch of science focused on understanding the evolutionary relationship between different species or populations.
• The analysis was done in a Bayesian manner – a statistical model that updates the probability for a hypothesis as more evidence or information becomes available.
• Significant amounts of new EIAV gag sequence information were added. The gag gene of retrovirus is responsible for making core proteins that provide structure to the virus.

Findings and Implications

• The analysis revealed a strong relation between geographic compartmentalization of EIAV and the phylogeographic history of modern horses, which means that the spread and evolution of EIAV strains may be directly correlated to how, when and where horse populations have moved and changed across the world.
• One of the primary findings of this research was the discovery that New World EIAV strains form a distinct group with a potentially common origin. New World typically refers to parts of the world like Americas, Oceania and Antarctica.
• The evidence intimates that a single “founder event” may have occurred during the 15th century when horses were reintroduced to the Americas by European colonists. A founder event occurs when a new population is established by a very small number of individuals from a larger population.
• This finding opens up a wide range of research avenues with implications in evolutionary and ecological studies. Gain in understanding of how viruses like EIAV have spread and evolved can provide insights into their adaptation and survival strategies, which can help in developing effective control measures and therapies.