Development and characterization of an infectious cDNA clone of the virulent Bucyrus strain of Equine arteritis virus.

This research focuses on the development of a comprehensive cDNA copy of the genome for the virulent Bucyrus strain of Equine arteritis virus (EAV). The researchers show that the strain, when replicated in horses, led to severe disease. This project aids in identifying the virulence determinants of this specific strain.

Objectives and Methodology

• The study’s primary goal was to create an infectious cDNA clone of the virulent Bucyrus strain of Equine arteritis virus. cDNA, or complementary DNA, is a form of DNA synthesized from a mature strand of messenger RNA by the enzyme reverse transcriptase. Having a cDNA clone allows researchers to study and manipulate the virus in a laboratory setting.
• Previous efforts in this field have resulted in the creation of two clones derived from a less harmful, cell culture-adapted variant of the original Bucyrus isolate of EAV. The new research aimed at creating a clone from the more harmful strain of the virus to provide more insight into the genetic determinants of EAV virulence.

Main Findings

• The researchers successfully developed a comprehensive cDNA copy of the genome of the virulent Bucyrus EAV strain and assembled this into a plasmid vector.
• Unlike the recombinant virus derived from previous cDNA clones (rEAV030), which was attenuated (reduced in virulence) in horses, the recombinant virus created using this new cDNA clone caused severe disease in horses.
• The disease was characterized by high fever (pyrexia), swelling (oedema), a decrease in white blood cells (leukopenia), high viral load (high-titre viraemia), and a substantial nasal shedding of the virus.

Significance annd Future Reseach

• The successful production of this infectious cDNA clone of a virulent EAV strain allows for detailed study of the determinants of virulence in this virus.
• With cDNA clones representing different virulence levels in horses, the researchers can conduct more comprehensive studies through reverse genetics, a method used to identify the function of a gene by analyzing the phenotypic effects of specific genes sequences.
• This research marks significant progress towards the characterization of the virulence determinants of EAV strains, which could lead to the development of targeted therapies or preventive measures against the disease.