Pathogenicity of equine herpesvirus 1 subtype 2 for foals and adult pony mares.

The research investigates the impact of equine herpesvirus 1 subtype 2 on pony foals and adult pony mares, demonstrating that it is a mild pathogen that can lead to unobvious clinical disease.

Research Participants and Procedures

• Three adult female ponies (mares) and four young ponies (foals) were selected as the subjects of the study.
• These ponies were all inoculated with the subtype 2 strain of equine herpesvirus 1, a prevalent disease among horses.

Findings and Observations

• After the inoculation, foals exhibited symptoms of a fever approximately 12 hours and 2.5 days later.
• Furthermore, a decrease in both neutrophils and lymphocytes (two types of white blood cells) was noted, followed by an increase in the total number of white blood cells (leukocytosis).
• On the other hand, the mares had a brief period of fever and decreased white blood cells about a day after the inoculation.
• However, these reactions were less severe in the mares as compared to the foals.

Immune Response and Virus Isolation

• An increase in the development of virus-neutralizing antibodies was observed in two of the three inoculated mares, but none of the foals.
• This suggests that the adult mares were better at resisting the virus than the younger foals.
• Despite these observations, the researchers were unable to isolate the virus from the blood of the research subjects.

Conclusions

• The research concludes that equine herpesvirus 1 subtype 2 is a fairly mild pathogen for ponies, as evident from the less severe symptoms in both mares and foals.
• Moreover, the infection may lead to unapparent clinical disease, which may be challenging to diagnose due to the mildness of the symptoms and the inability to isolate the virus from blood.