Dugbe virus in ticks: histological localization studies using light and electron microscopy
Different methods for the detection and histological localization of Dugbe (DUG) virus infection in vertebrate and tick cells and tissues were compared. Immunohistochemistry with DUG-specific antibody and hybridocytochemistry with a DUG-specific riboprobe were used to investigate the role of different tick cell types in the replication of DUG virus and its tissue tropisms during internal dissemination. DUG virus was localized in both unfed and feeding adults inoculated as nymphs or orally infected by capillary feeding. In non-feeding ticks the main sites of DUG virus replication were the epidermis, hemocytes associated with loose connective tissue and a small number of phagocytic digestive cells in the gut lumen. DUG virus invaded the salivary glands during feeding and was not detected until after 7–10 days feeding on the host. Virus infection increased in the gut during feeding from about 1% to about 40% of cells. The primary site of transstadial persistence of DUG virus is the hemocytes. In the electron microscope, no virus particles or pathological effects were observed in ticks. Tick hemocytes and other motile cells may be important in the transmission of persistent virus infection from one cell or organ to another by diapedesis.
KeywordsSalivary Gland Immunogold Labelling Digestive Cell Ixodid Tick Infected Tick
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