Molecular epidemiology and genetic characterization of equine arteritis virus isolates associated with the 2006-2007 multi-state disease occurrence in the USA.

This research article investigates equine viral arteritis (EVA) outbreaks in the USA from 2006-2007, specifically focusing on the genetic characteristics of the equine arteritis virus (EAV) isolates from these outbreaks. The aim was to understand the origin and spread of the EVA illness during these periods and deduce how the virus changes over time in infected animals.

Study Context and Objectives

• The study was aimed at understanding the genetic characteristics of the EAV isolates associated with the 2006-2007 outbreaks of EVA. This was the first time EVA was confirmed in Quarter Horses in multiple states.
• The main objectives included identifying the origin of EAV strains causing the outbreaks, observing the genetic evolution of the virus in infected animals, and understanding the connection between different EVA outbreaks.

Research Methodology and Findings

• The researchers captured and analyzed the full genome of an EAV isolate from New Mexico, which was the index (initial) premises. The genome was found to have unique genetic insertions that were previously unrecorded.
• Further sequence analysis was performed on additional isolates from states including New Mexico, Utah, Kansas, Oklahoma and Idaho. The isolates contained similar unique insertions, suggesting that the multiple outbreaks likely originated from a same EAV strain.
• Another significant finding was that an EAV isolate from a Utah aborted fetus exhibited a different neutralizing phenotype, implying a potential variation within the virus strain.
• Finally, the researchers also mapped the genetic evolution of EAV in infected carrier stallions by sequencing 18 isolates made sequentially from these animals. It was observed that the virus’s genetic composition changed over time and varied depending on individual animals and the duration of virus shedding.

Implications and Significance of the Study

• The study highlights the importance of genetic characterization in understanding disease transmission and management. By genetically mapping the EAV strain, the researchers demonstrated how a single strain could be the source of multiple outbreaks.
• The work potentially contributes to effective EVA outbreak management strategies and could augment the development of improved viral countermeasures and therapies.
• Knowledge about the genetic evolution of viruses during persistent infection, as shown in this study, might be useful in developing effective treatment strategies for not only EVA, but also other similar viral infections in general.