Molecular epidemiology and pathogenesis of some equine herpesvirus type 1 (equine abortion virus) and type 4 (equine rhinopneumonitis virus) isolates.

This study investigates the molecular characteristics and pathogenesis of two types of equine herpesvirus (EHV1 and EHV4) that cause abortion and respiratory illnesses in horses, respectively. Researchers analyzed the DNA fingerprints of these viruses isolated from affected horses and found unique traits linked with the diseases they cause.

Overview of the Study

• The authors collected strains of EHV1 and EHV4 from a diseased foetus and a horse suffering from a respiratory infection, rhinopneumonitis, respectively.
• They isolated EHV1 from a horse that had succumbed to myeloencephalitis (a nervous system inflammatory condition), providing a compelling link between the virus and the disease.
• Notably, EHV1 was also isolated from a mare that had aborted a foetus around the same time – underscoring the virus’ implications in equine abortions.

DNA Fingerprint Analysis

• Researchers analyzed the “restriction endonuclease DNA fingerprints” of the EHV1 and EHV4 viruses, which is a kind of DNA profile created using specific enzymes (restriction endonucleases). This technique helps identify differences and similarities across different virus strains.
• The DNA fingerprint of each virus strain was found to be typical of the disease they were associated with, thereby corroborating earlier findings, and supporting the idea that different equine health problems can be linked to specific EHV types.

Differences in EHV1 Strains

• The EHV1 strain found in the horse with inflammation of the nervous system (myeloencephalitis) was compared to EHV1 strains not known to be involved in this disease.
• The DNA fingerprints of the myeloencephalitis-causing EHV1 strains were distinct from the other EHV1 viruses, suggesting there could be multiple strains of EHV1 with different disease-causing potentials.

EHV4 and Horse Abortion

• The researchers induced abortion in a horse using EHV4 and compared the DNA fingerprint of this virus with the virus recovered from the aborted foetus.
• Their results showed no noticeable differences, indicating that virus passage through the foetus did not impact the DNA fingerprint of the virus, potentially suggesting the stability of EHV4.

This research offers valuable insights into understanding the pathogenesis and molecular epidemiology of equine herpesviruses, ultimately aiding in the diagnosis, prevention and treatment of diseases caused by these viruses in horses.