Growth and virulence alterations of equine herpesvirus 1 by insertion of a green fluorescent protein gene in the intergenic region between ORFs 62 and 63.

This research analyses the nucleotide sequences of equine herpesvirus 1 (EHV-1) and creates a mutant strain by introducing the green fluorescent protein gene into a specific area of the virus. The authors found this alteration causes the mutant strain to display less virulence and differences in growth patterns when compared to the original strain of EHV-1, suggesting that the area in the virus where the gene was introduced plays key roles in the characteristics of the virus.

Explanation of the Research Article

• Analysis of Nucleotide Sequences : The researchers analyzed the part of the EHV-1 DNA, called the intergenic region between ORF 62 and ORF 63. The analysis compared the series of nucleotides that make up EHV-1’s DNA in this area. They found conserved and variable domains between different EHV-1 isolates. A conserved domain is a section of DNA that is common among different isolates (or versions) of EHV-1, while a variable region differs amongst the isolates.
• Construction of Mutant Strains and their Properties : The researchers devised two mutant strains, named Ab4-GFP and Ab4-loxP, altering the intergenic region between ORF 62 and ORF 63. The Ab4-GFP strain was made by inserting a gene that produces green fluorescent protein, flanked by lox P sites. This allows the protein to be detected easily. The Ab4-loxP strain was created by removing the green fluorescent protein from the Ab4-GFP strain, leaving behind only a single lox P site. The modified Ab4-GFP displayed decreased viral production and smaller plaque formations compared to the wild type (non-modified) EHV-1 in MDBK cells (a kind of cattle kidney cell). Furthermore, Ab4-GFP displayed weaker virulence, or disease-causing ability, in both mice and hamsters in comparison to the unaltered EHV-1. However, the characteristics of Ab4-loxP were similar to those of the wild type.
• Implication : This research suggests a significant role for the intergenic region between ORF 62 and ORF 63 in the EHV-1 virus. As modifications in this area led to changes in the virus’s growth and virulence, it suggests it plays a critical role in the general functionality and disease-causing ability of the virus. Hence, this region of the virus can be considered a potential target for future antiviral therapies or vaccine development.