Pathogenicity and immunologic studies of equine adenovirus in specific-pathogen-free foals.

The research focuses on the study of the effects and immunity to equine adenovirus (EAdV) in specific-pathogen-free foals. The study establishes the variations in symptoms and disease progression in the foals based on their inoculation times, with considerations like maternal immunity and artificial immunization influencing the outcomes.

Experimental Setup

• The study involved three foals. Two of them were delivered through cesarean section and didn’t suckle; these were raised in isolation. The third foal suckled for 12 hours before isolation.
• Each of these foals was verified to be free from specific pathogens, ensuring a controlled experimental environment.

Experiment Execution

• Foal 1 was inoculated with EAdV at 44 days old, when its immune system was fully developed. It displayed symptoms of conjunctivitis, diseases of the upper respiratory tract, and pneumonia.
• Foal 2, who suckled from its mother before isolation, was inoculated when it was only four days old. Similar symptoms were observed in Foal 2. However, there were noticeable differences in the manifestation of the disease and necropsy findings which are assumed to result from the influence of the mother’s antibodies.

Immunization and Challenge Exposure

• Foal 3 was given two subcutaneous injections of EAdV along with an adjuvant to stimulate its immune response. Post the challenge exposure to EAdV, this foal displayed no clinical symptoms.
• On examination six days after exposure, pathologic lesions in the respiratory tract of Foal 3 were considerably less than those found in the first two foals, suggesting effective immunization.

Conclusions and Relevance

• The research outcomes demonstrated the varying degrees of impact and progression of the EAdV infection based on the age and immune status of the foals at the time of inoculation.
• Furthermore, the study provides vital inputs about the role of maternally derived antibodies and artificial immunization in providing immunity against EAdV.
• The findings are significant for gaining a broader understanding of EAdV immunity and setting potential paths for effective prevention and treatment modalities.