Attenuation of the neuropathogenic equine herpesvirus type 1 strain Ab4p in hamsters by a single amino acid mutation (D752N) in viral DNA polymerase ORF30.

The research investigates how a single mutation in the DNA polymerase gene of the equine herpesvirus type 1 (EHV-1), a disease-causing agent in horses, can reduce its neurotoxicity in hamsters.

Introduction to Equine Herpesvirus Type 1 (EHV-1)

• Equine herpesvirus type 1 (EHV-1) is a common and serious disease-causing agent in horses that can lead to various conditions such as abortion, respiratory infection, and neurological diseases.
• A specific type of neurological disease caused by EHV-1 is referred to as equine herpesvirus myeloencephalopathy.

Role of DNA Polymerase ORF30 Gene in EHV-1 Neuropathology

• The study delves into a single nucleotide polymorphism (SNP), a variation at a single position in a DNA sequence among individuals, associated with a single amino acid in the DNA polymerase gene (ORF30).
• In the context of the EHV-1, this SNP relates to the substitution from D752, a neuropathogenic variation, to N752, a non-neuropathogenic variation.
• Neuropathogenicity refers to the ability of a virus or other pathogenic organism to cause disease in the nervous system.

The D752N Mutation Impact on EHV-1 Neuropathogenicity

• The researchers conducted an experiment wherein they constructed an EHV-1 with the N752 variation of the ORF30 gene, known as the Ab4p ORF30 N752 mutant, along with a repair virus.
• This experiment was undertaken to examine the effect of the D752N mutation on the neuropathogenicity of the virus in Syrian hamsters.
• The findings indicated that the N752 mutation did not affect the viral growth in cultured cells. In other words, it did not influence the virus’s ability to replicate and grow in a lab-controlled environment using cultured cells.
• However, the mutation significantly reduced the neuropathogenicity of the Ab4p virus strain in the hamsters, implying that it lessened the virus’s ability to cause neurological diseases.

Implication of Findings

• The research suggests that the D752N mutation is involved in neuropathogenicity not only in horses, where EHV-1 naturally exists, but also in hamsters.
• This discovery enhances our understanding of how viral neuropathogenicity may be attenuated or reduced, and may offer potential strategies for preventing or treating neurological diseases linked to EHV-1 in horses and possibly other species.