One problem with dengue virus is that one infection does not protect against a subsequent infection; secondary infections can result in the severe immunopathology of dengue hemorrhagic fever. Dejnirattisai et al. derived a panel of monoclonal antibodies specific for dengue viruses. These antibodies were mainly directed against the dengue virus precursor membrane protein (prM), and most cross-reacted with all four dengue serotypes. The antibodies were not capable of fully neutralizing the virus, but instead promoted immune responses over a wide range of concentrations. During virus production and virion assembly, maturation of prm is often incomplete, and, consequently, a major part of the host’s natural antibody response recognizes a component that is present in variable numbers on the virion. Thus, rather than resulting in complete neutralization, the antibody response promotes virus infection of cells that carry receptors for antibodies.
W. Dejnirattisai, A. Jumnainsong, N. Onsirisakul, P. Fitton, S. Vasanawathana, W. Limpitikul, C. Puttikhunt, C. Edwards, T. Duangchinda, S. Supasa, K. Chawansuntati, P. Malasit, J. Mongkolsapaya, G. Screaton, Cross-reacting antibodies enhance dengue virus infection in humans. Science 328, 745–748 (2010). [Abstract] [Full Text]