Immune responses and severe dengue: what have we learned?

Purpose of review With the marked rise in dengue globally, developing well tolerated and effective vaccines and therapeutics is becoming more important. Here we discuss the recent developments in the understanding of immune mechanisms that lead to severe dengue and the learnings from the past, that can help us to find therapeutic targets, prognostic markers, and vaccines to prevent development of severe disease. Recent findings The extent and duration of viraemia often appears to be associated with clinical disease severity but with some variability. However, there also appear to be significant differences in the kinetics of viraemia and nonstructural protein 1 (NS1) antigenemia and pathogenicity between different serotypes and genotypes of the DENV. These differences may have significant implications for development of treatments and in inducing robust immunity through dengue vaccines. Although generally higher levels of neutralizing antibodies are thought to protect against infection and severe disease, there have been exceptions and the specificity, breadth and functionality of the antibody responses are likely to be important. Summary Although there have been many advances in our understanding of dengue pathogenesis, viral and host factors associated with occurrence of severe dengue, vascular leak and the immune correlates of protection remain poorly understood.