Non Fc receptor-mediated infection of human macrophages by dengue virus serotype 2

Four human monocyte-derived macrophage membrane proteins, with apparent molecular masses of 27, 45, 67 and 87 kDa, were identified as possible receptors for dengue virus serotype 2 (DEN-2) (Mexican isolate 200787/1983), based on affinity chromatography, immunofluorescence, virus overlay protein-binding assays and Western blotting. Additionally, mouse polyclonal antibodies raised against each of the four proteins were capable of partially inhibiting in vitro DEN-2 infection of monocyte-macrophages, thus supporting the notion of a role for such proteins as DEN-2 receptors. Parallel studies were carried out using the human promonocytic U-937 cell line, both as undifferentiated cells and as monocyte-like phorbol myristate acetate (PMA)-differentiated cells, as target cells. Whereas interaction between DEN-2 and undifferentiated U-937 cells was almost negligible, PMA-differentiated U-937 cells were shown to harbour putative receptors (with molecular masses of 45 and 67 kDa) for DEN-2, similar to those found in human monocyte-derived macrophages. To our knowledge, this is the first report that describes putative receptors for DEN-2 in primary cultures of human macrophages.