Increased multiplication of dengue virus in mouse peritoneal macrophage cultures by treatment with extracts of Ascaris-Parascaris parasites.

Methylcellulose-elicited peritoneal macrophages from BALB/c mice were cultivated in vitro and inoculated with dengue virus (DV). At intervals thereafter portions of the culture fluids were taken and titrated for viral infectivity. Extracts from Ascaris suum and Parascaris equorum, either crude or Sephadex G-100 fractionated, were examined for effects on the multiplication of DV.

Antibody-mediated enhancement of dengue virus infection in mouse macrophage cell lines, Mk1 and Mm1.

Antibody-mediated enhancement of dengue type 2 virus (D2V) replication in murine macrophage cell lines (Mk1 and Mm1) was studied. While both Mk1 and Mm1 supported D2V replication in the absence of enhancing antibodies, virus production was enhanced when both cell lines were inoculated with D2V in the presence of dengue type 1 virus (D1V)-hyperimmune rabbit IgG, D1V-hyperimmune mouse ascitic fluids, or D2V-hyperimmune mouse ascitic fluids at subneutralizing concentrations. The enhancement ratios were greater in Mk1 than in Mm1.

Dengue type 2 virus infection in human peripheral blood monocyte cultures.

Dengue type 2 virus (D2V) infection in cultured human monocytes was studied. D2V permissiveness of the monocytes was enhanced when the cells were inoculated with D2V in the presence of either polyclonal or type-specific monoclonal anti-dengue antibody. The enhancement of D2V permissiveness mediated by the antibodies was more clearly demonstrated when the monocytes had been treated with trypsin before virus inoculation, though treatment of the cells with trypsin alone decreased D2V permissiveness.