Study will pave way to develop biomarkers and a good vaccine

The NS1 antigen (toxin) is a “nasty” piece of work, reiterates Prof. Neelika Malavige, explaining its ‘profile’ before focusing on her research team’s findings.

When the mosquito carrying the dengue virus takes a bite and injects this virus into the human body, the NS1 antigen acts as a separate entity within the body. It secretes protein which causes a lot of trouble – attacking the white blood cells called monocytes and macrophages both vital in fighting off ‘invaders’ like viruses and also many other cells. When attacking the monocytes and macrophages, the NS1 antigen makes these cells in some people to produce inflammatory mediators causing severe disease.

Prof. Malavige and her team have discovered that the type of antibodies created due to the invasion of the NS1 antigen differed in those with mild dis- ease (Dengue Fever -- DF) as opposed to those who were struck by severe disease (Dengue Haemorrhagic Fever -- DHF). The results are likely to pave the way to further understand why only some people develop very severe disease but others have mild or asymptomatic (showing no symptoms) illness.

Spectacular findings which will help in the development of a biomarker (in medicine, a biomarker is a measurable indicator of the severity or presence of some disease state) for dengue as well as a good vaccine which has protective antibodies against NS1.

Prof. Malavige says that in the case of a biomarker, it would be helpful in differentiating between mild and severe illness which, in turn, would lead to fewer people having to undergo close monitoring in hospitals at the cost of much time, effort and money. “Then we will be able to pick out those who have DF and DHF, with admission to hospital being required only for those with DHF.”

Referring to the development of a vaccine against dengue, she stressed that the antibodies which are created to the NS1 antigen in severe dengue would be very useful. However, there is a lot more work to be done to fully understand how different types of NS1 antibodies are generated and the mechanisms through which they cause severe dengue.

So far, one dengue vaccine -Dengvaxia® (CYD-TDV) -- developed by Sanofi Pasteur has been licensed in some countries, while five more dengue vaccine candidates are in clinical development or in the pipeline.

Some experts across the world speculate that the “less than expected efficacy” of Dengvaxia may be due to the lack of the generation of antibodies against the NS1 antigen.