Detection of higher levels of dengue viremia using FcγR-expressing BHK-21 cells than FcγR-negative cells in secondary infection but not in primary infection.

It has been reported that levels of viremia reflect the severity of illness in dengue virus infection. We assessed the levels of viremia in patients with primary and secondary infections, using 2 cell lines: FcγR-expressing BHK cells and FcγR-negative cells. In primary infection, virus titers were at similar levels between FcγR-expressing and FcγR-negative cells. In secondary infection, however, virus titers were ∼10 times higher in FcγR-expressing cells on days 1-6 when compared with FcγR-negative cells, indicating discrepancy in viremia titers between FcγR-expressing and FcγR-negative cells. The results suggest that dengue virus-antibody complexes with infectious capacity exist in patients with secondary infection, and these immune complexes can be detected by using FcγR-expressing cells. As it has been reported that principal target cells of dengue virus infection are FcγR-positive, monocyte/macrophage lineage cells, virus titers determined using FcγR-expressing cells may better reflect the actual viremic conditions in vivo.