Systematic Veterinary Virology

LABORATORY DIAGNOSIS

• Isolation and identification
• Clinical materials: Vesicular fluid, scabs and skin scrapings of lesions and lesions in the respiratory and gastro-intestinal tract.
• Isolation system: Primary or secondary cultures of lamb testis (LT) or lamb kidney (LK) cells.
• Identification: immunofluorescence, staining of intracytoplasmic inclusion bodies, inhibition of cytopathic effect using positive serum, ELISA or by PCR.
• Electron microscopy
• Histology: Formalin-fixed biopsy materials and tissue sections are stained by H&E for characteristic histopathological changes.
• The most striking aspects of acute-stage skin lesions are a massive cellular infiltrate, vasculitis and oedema.
• Early lesions are characterised by marked perivascular cuffing. Initially infiltration is by macrophages, neutrophils and occasionally eosinophils, and as the lesion progresses, by more macrophages, lymphocytes and plasma cells.
• A characteristic feature of all capripoxvirus infections is the presence of variable numbers of ‘sheep pox cells’ in the dermis. These sheep pox cells can also occur in other organs where microscopic lesions of sheep and goat pox are present. These cells are large, stellate cells with eosinophillic, poorly defined intracytoplasmic inclusions and vacuolated nuclei.
• Immunological methods: These methods are used to detect SGPV either on the tissue culture fluid or from the lesions. Some of the common immunological methods are
• AGID
• ELISA
• FAT
• Nucleic acid identification methods: The PCR is be used to detect the capripoxvirus genome in biopsy or tissue culture samples.