Introduction
Dengue is one of the most important emerging infections with 50% of the world’s population living in dengue endemic countries. The clinical spectrum of disease can range from asymptomatic to a severe haemorrhagic illness. Those with secondary infection with a second serotype are most at risk of severe disease. This has lead to the theory that a primed immune response ineffectively clears a secondary infection and enhances infection. Teasing out immunology to dengue has become important in aiding effective and safe vaccine design. In this project, I investigated the antibody response of a case of acute severe primary dengue.
Methods
Activated B cells were isolated from a patient with acute severe dengue virus. Recombinant monoclonal antibodies (mAbs) were produced and investigated. The mAbs were assessed for: their ability to recognise dengue; epitopes to which they bind; which amino acids of the structural proteins they bind to.
Results
88 IgH-Igλ and 44 IgH-Igκ recombinant IgG antibodies were produced. 44 mAbs were investigated further. Seven of the mAbs showed reactivity to dengue, 3 reacting to dengue 1 alone, 3 had cross reactivity to all four serotypes and JE. Western blot revealed that no antibodies bound to prM or E. A viral like protein (VLP) library was created for further assessment of epitope binding.
Discussion
IgG was produced to dengue despite the early time point. Interestingly 43% (n=3) of antibodies were specific to the infecting dengue serotype, but a further 43% were reactive to all four dengue serotypes. The epitopes for these mAbs were not demonstrated. This may be due to changes to the E and prM proteins during the Western blot that mAbs recognise other epitopes or else the mAbs react to tertiary structure epitopes. Use of the VLP library to identify the amino acid residues necessary for binding would help in understanding the epitopes.