ANTIBODY-RESPONSES TO AN IMMUNODOMINANT-NONSTRUCTURAL-1 SYNTHETIC PEPTIDE IN PATIENTS WITH DENGUE-FEVER AND DENGUE HEMORRHAGIC-FEVER

Two flaviviruses, dengue (DEN) virus and Japanese encephalitis (JE) vi rus, are important because of their global distribution and the freque ncy of epidemics in tropical and subtropical areas. To study the B-cel l epitopes of nonstructural 1 (NS1) glycoprotein and anti-NS1 antibody response in DEN infection, a series of 15-mer synthetic peptides from the predicted B-cell linear epitopes of DEN-2 NS1 protein were prepar ed. Enzyme-linked immunosorbent assay (ELISA) was performed to analyze antibody responses to these peptides from sera of both DEN and JE pat ients. One peptide derived from DEN-2 NS1, D2 NS1-P1 (amino acids 1-15 ), was identified as the immunodominant epitope that reacted with sera from dengue fever (DF) patients but not JE patients. The isotype of D 2 NS1-P1-specific antibodies was mainly immunoglobulin M (IgM) in ail sera that tested positive. A specificity study demonstrated that sera from all four DEN types reacted with D2 NS1-P1. A dynamics study showe d that specific a nti bodies to this peptide could be detected as earl y as 2 days after the onset of symptoms. We observed significant anti- D2 NS1-P1 antibody responses in 45% of patients with primary and secon dary infections with DF or with dengue hemorrhagic fever. This is the first report demonstrating that significant anti-DEN NS1 antibodies ca n be induced in the sera of patients with primary DEN infection. J. Me d. Virol. 57:1-8, 1999. (C) 1999 Wiley-Liss, Inc.