Recovery of Swedish Equine arteritis viruses from semen by cell culture isolation and RNA transfection.

The research paper is about the successful extraction of infectious Equine arteritis virus (EAV) from preserved semen of infected Swedish stallions, accomplished through cell cultivation and RNA transfection methods.

Research Methods

• The primary goal of this research was to recover the infectious Equine arteritis virus (EAV) from the semen of infected Swedish stallions. Two different methods were employed – classical cell culture isolation and transfection of the extracted total RNA.
• With the help of these methods, the virus was sought to be recovered from semen samples stored under different conditions – several months at -20 degrees Celsius, extended semen, and fresh semen stored at -70 degrees Celsius or directly used after sampling.
• The cell culture technique was successful with fresh, unextended semen stored at -70 degrees Celsius or directly used after sampling. However, the recovery of virus from semen samples stored for several months at -20 degrees Celsius or from extended semen was only possible by transfecting the extracted RNA.

Nucleotide Sequencing and Phylogenetic Analysis

• Simultaneously, the viruses were examined in the variable region of the large glycoprotein GP5. This was achieved by using nested RT-PCR and direct nucleotide sequencing methods.
• The obtained sequences were then integrated into a large phylogenetic tree from this region. A phylogenetic analysis shows the evolutionary relationships among various biological species.
• The findings prove that the Swedish strains of EAV are part of multiple diverse phylogenetic groups. This indicates that the EAV strains in Sweden have a wide genetic diversity.

Significance of the Findings

• This study marks the first ever report of recovering infectious EAV from archived semen samples through RNA transfection. It unveils novel ways to detect and study viruses in preserved samples, greatly benefitting future research in viral study and detection. Additionally, it contributes to our understanding of the evolution and diversity of Equine arteritis virus strains.