Identification of a novel equine infectious anemia virus field strain isolated from feral horses in southern Japan.

The research article discusses the discovery of a new field strain of equine infectious anemia virus (EIAV), which was found in feral horses in southern Japan.

Introduction

• The paper begins by providing some context about equine infectious anemia (EIA), a disease that has been known for over 150 years.
• The study focuses on two previously known strains of the EIA virus, namely EIAV(Wyoming) and EIAV(Liaoning).
• In 2011, EIA was discovered among the feral Misaki horse population in the Toi-Cape area of southern Japan. This led to the amplification and characterization of a new EIAV strain from the peripheral blood drawn from these infected horses.

Miyazaki2011-A Strain

• The newly identified strain, called Miyazaki2011-A, has a provirus (a virus genome that is integrated into the DNA of a host cell) that is 8208 base pairs (bp) long. This length, along with the general genomic organization, is typical for the EIAV.
• However, the new field strain shows relatively low nucleotide sequence compatibility with the two known EIAV strains – 77.2% with the EIAV(Wyoming) and 78.7% with the EIAV(Liaoning).

Origination of Miyazaki2011-A strain

• The researchers used a similarity plot analysis to determine the origins of the new strain. The analysis suggests that Miyazaki2011-A, EIAV(Wyoming), and EIAV(Liaoning) arose independently, indicating that they do not share a common ancestor.
• When the researchers compared sequences from all EIAV-infected horses to other known viral strains, phylogenetic studies indicated that the Japanese isolates make up a separate monophyletic group. In other words, they all appear to have evolved from a single common ancestor that is not shared with any other group.