Pathogenesis of caprine herpesviral infection in does and neonatal kids

Abstract

The pathogenesis of caprine herpesviral infection of goats was investigated in 14 neonatal kids and 18 pregnant does. Clinical observations, hematologic tests, virus isolation procedures, evaluations of cell mediated and humoral immune responsiveness, gross pathology, histopathology, and immunofluorescent microscopy were utilized at selected intervals to define the pathogenesis following inoculation of goats with a California isolate of caprine herpesvirus (CHV). The disease induced in kids following combined oral and intranasal inoculation was characterized clinically by lack of fever, conjunctivitis, rhinitis, and occasionally by diarrhea. Gross and microscopic lesions in kids were not numerous or severe and appeared to be caused by viral cytolysis of the epithelial cells of the mucous membranes of the eye, nose, and digestive tract. Cytolysis of cells resulted in erosions and ulcerations of the affected mucous membranes. Indications of systemic dissemination of the virus were limited to random foci of coagulative necrosis in the cortical areas of the retropharyngeal lymph nodes of 2 kids and the detection of viral antigens by immunofluorescence in the retropharyngeal lymph node of 1 of those kids. Increased lymphocyte blastogenic response to CHV in the whole blood lymphocyte transformation test in 7 of 11 kids between postinoculation day (PID) 4 and 8 indicated a cell mediated response was induced. There also was a humoral immune response characterized by the elevation of serum neutralization titers to CHV in 5 of 6 kids between PID 8 and 14. Recovery from the disease appeared to be primarily dependent upon macrophages and neutrophils. Lymphokines from activated T-cells probably enhanced the activity of macrophages. The intravenous inoculation of pregnant does with CHV produced a more severe disease than the intranasal inoculation of the neonatal kids. Clinically, the infection in does was manifested by fever, rhinitis, conjunctivitis, diarrhea, and abortions. All clinical signs except abortions occurred within 72 hours postinoculation. Abortions were observed in only 2 does and both occurred on PID 10 after all other clinical signs had subsided. Live normal kids were born to other does on PID 4, 6, and 12. Hematologic evaluations revealed a transient lymphopenia on PID 3 and 6 in several does...