EQUINE HERPESVIRUS-2 IN PULMONARY MACROPHAGES OF HORSES

In a search of viral agents in pulmonary macrophages of horses with ch ronic pulmonary disease, equine herpesvirus 2 was found to be unique. In 8 of 9 horses with chronic pulmonary disease, antigens of equine he rpesvirus 2 were detected by indirect immunofluorescence staining of s cattered foamy macrophages immediately after harvesting by bronchoalve olar lavage and fractionation on metrizamide gradients. In a healthy h orse, antigens were not found. After 1 week of cultivation of bronchoa lveolar lavage cells from a second group of 9 horses with chronic pulm onary disease, viral antigens were detected in 90% of the adherent pul monary macrophages. In 2 of 3 healthy horses, viral antigens also were found in 90% of the adherent pulmonary macrophages. Antigens of equin e herpesvirus 1, equine herpesvirus 4, parainfluenza virus 3, or adeno virus were not detected. Antigens of the 5 investigated viruses also w ere not detected in lung tissue slices from a third group of 14 horses : 4 healthy; 7 with varying degrees of bronchiolitis, 2 of which also had chronic intestitial pneumonia; 2 with eosinophilic bronchitis; and 1 with pulmonary hemorrhage. The exclusive presence of equine herpesv irus 2 in pulmonary macrophages was confirmed qualitatively by isolati on of infective virus by cocultivation. Ln a fourth group of 12 horses with chronic pulmonary disease, infective virus could be isolated fro m pulmonary macrophages of 3 horses and from mixed-blood leukocytes of 5 horses. Virus isolations from 2 healthy horses were not successful from pulmonary macrophages, whereas 1 isolation was obtained from mixe d-blood leukocytes. Other viruses were not detected by cocultivation.