Dengue fever is a mosquito-borne infection, caused by four subtypes of the dengue virus. Globally it is endemic in over 100 countries, with an estimated 390 million cases occurring each year. In most cases, dengue is a flu-like illness and is cleared by the body’s immune system. However there is a risk of progression to a haemorrhagic fever – which can be fatal.
Currently there is no treatment and fighting the infection is left to the body’s immune system. As part of the normal immune response, white blood cells produce specific antibodies that bind to parts of the invading virus and label them for destruction. Following recovery, the body retains the ability to produce these antibodies and the person becomes immune to reinfection. However, these antibodies are usually specific to one subtype and offer no immunity to infection by the other three. In fact people are at an increased risk of severe complications during subsequent infections.
The team at Imperial College studied antibodies produced following dengue infection and discovered a new class of antibody, which is effective against all four viral subtypes. These antibodies target a molecular bridge between two proteins that is common to all four virus types.
Excitingly these antibodies could be used in the treatment of dengue, or in the development of a new vaccine. This vaccine would contain this molecular bridge and would stimulate the immune system to produce antibodies against it. The immune system would then be able to recognise and neutralise any dengue virus.
The incidence of dengue is climbing rapidly, despite all efforts to contain it. 40% of the world’s population live in endemic areas and risk multiple dengue infections and severe complications. While there are vaccines being trialled, none of them offer full protection. The hope is that this discovery can offer a new approach to treat infection by all dengue subtypes.
Nicole Samuel is a fifth year medical student
Images: Dengue warning sign in Cambodia by Christopher; Dengue vaccine trial clinic in Thailand by Sanifi Pasteur (Flickr, Creative Commons)