Characteristics of respiratory tract disease in horses inoculated with equine rhinitis A virus.
OBJECTIVE
To develop a method for experimental induction of equine rhinitis A virus (ERAV) infection in equids and to determine the clinical characteristics of such infection.


METHODS
8 ponies (age, 8 to 12 months) seronegative for antibodies against ERAV. PROCEDURES-Nebulization was used to administer ERAV (strain ERAV/ON/05; n = 4 ponies) or cell culture medium (control ponies; 4) into airways of ponies; 4 previously ERAV-inoculated ponies were reinoculated 1 year later. Physical examinations and pulmonary function testing were performed at various times for 21 days after ERAV or mock inoculation. Various types of samples were obtained for virus isolation, blood samples were obtained for serologic testing, and clinical scores were determined for various variables.


RESULTS
ERAV-inoculated ponies developed respiratory tract disease characterized by pyrexia, nasal discharge, adventitious lung sounds, and enlarged mandibular lymph nodes. Additionally, these animals had purulent mucus in lower airways up to the last evaluation time 21 days after inoculation (detected endoscopically). The virus was isolated from various samples obtained from lower and upper airways of ERAV-inoculated ponies up to 7 days after exposure; this time corresponded with an increase in serum titers of neutralizing antibodies against ERAV. None of the ponies developed clinical signs of disease after reinoculation 1 year later.


CONCLUSIONS
Results of this study indicated ERAV induced respiratory tract disease in seronegative ponies. However, ponies with neutralizing antibodies against ERAV did not develop clinical signs of disease when reinoculated with the virus. Therefore, immunization of ponies against ERAV could prevent respiratory tract disease attributable to that virus in such animals.
Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON, N1G 2W1, Canada., Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON, N1G 2W1, Canada.
Andrés
A
Diaz-Méndez
Joanne
J
Hewson
Patricia
P
Shewen
Eva
E
Nagy
Laurent
L
Viel
D000818:Animals; D057134:Antibodies, Neutralizing / Q000097:blood; D000914:Antibodies, Viral / Q000097:blood; D005537:Aphthovirus / Q000276:immunology; D001831:Body Temperature; D006734:Horse Diseases / Q000276:immunology / Q000473:pathology / Q000821:virology*; D006736:Horses; D010850:Picornaviridae Infections / Q000276:immunology / Q000473:pathology / Q000662:veterinary* / Q000821:virology; D012140:Respiratory Tract Diseases / Q000276:immunology / Q000473:pathology / Q000662:veterinary* / Q000821:virology; D012698:Serologic Tests / Q000662:veterinary
D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral