Ultrastructural and Immunocytochemical Demonstrations of Dengue Type 2 Virus in C6/36 and Vero Cells During Virus Infection

The infection and maturation of Dengue type 2 virus in C6/36, AP61 and Vero cells are demonstrated after 5, 30 minutes, 2, 4 hours to 3, 6, 8 and 10 days of infection bye the electron microscopy and immuncytochemistry. Cytopathic effect were identified for successful infection by immuno-peroxidase reaction by antibody against envelope protein Env of the envelopcapsid of Dengue-2 virus. Residues of viruses were left on the extracellular cell surface at early infection of Vero cells with Dengue 2 viruses. Internalization of viruses at the early stage of infection by endocytosis was observed in Vero cells. Ultrastructural and indirect immuno-gold ABC labeling detected by Ab-Env indicated that maturation of the viruses occurred in the intracellular vacuoles. Virus crystals were observed in the cytoplasm of C6/36 cells. Involvement of endoplasmic reticulum and nucleus in the maturation of virus in C6/36 cell were observed. The Golgi apparatus was negative of Env-peroxidase labeling. The virus seems to be released from the host cells by breaking down of the vacuoles through the cell membrane. There were no viruses observed budding from the host membrane after 6 and 10 days of infection. The viruses in residue cytoplasm and nearby dense materials are Env-positive from immuno-gold or peroxidase reactions. The results suggested that Env is not incorporated into the virion until breakdown of the vacuole.