Dugbe Virus: a Tick-borne Arbovirus from Nigeria

SUMMARY Dugbe virus multiplied in cell lines of pig and monkey origin producing little gross cytopathogenic effect, but prominent paranuclear, cytoplasmic inclusions were evident in stained preparations examined by light microscopy. Electron microscopic examination of thin sections of Dugbe virus-infected PS cells showed numerous virus particles 90 to 100 nm in diam. on the cell membrane and in cytoplasmic vacuoles. No virus particles were seen in inclusions, although these contained virus antigens demonstrable by immunofluorescence. A marked prozone effect was seen in plaque titrations performed under carboxymethyl cellulose overlay. Dugbe virus-infected PS cells continued to divide and a chronically infected culture was established, which was resistant to superinfection with homologous virus. However, three togaviruses, Semliki Forest, yellow fever and Uganda S viruses, and Tahyna virus, multiplied almost as well in the Dugbe carrier culture as in control cells; Bwamba and Nairobi sheep disease viruses gave reduced yields in the Dugbe carrier cultures. It is suggested that the interference phenomenon reveals arbovirus relationships not demonstrable by conventional serological tests.