The virus that causes winter vomiting disease invades cells by attaching to particular sugar molecules on the surface of the cells. This is the conclusion of a thesis presented at the Sahlgrenska Academy, University of Gothenburg, Sweden. This result may be an important step in the development of a drug against the regular hospital-based epidemics caused by the virus.
Winter vomiting disease is an infectious inflammation of the gastro-intestinal tract, which occurs principally during the winter months. There is presently no vaccine, and no drugs to combat the infection. The disease causes diarrhoea and vomiting, and its consequences may be very serious for people who are already seriously ill or weak.
"We are aiming to develop a drug that can be given to vulnerable persons and to children in day-care when it has become clear that another epidemic is starting to break out. More research will, however, be required. Our results are important steps along the way, but it will probably be several years before a drug is commercially available", says Gustaf Rydell who successfully defended his PhD thesis on June 8, 2009.
The thesis describes how the virus for winter vomiting disease can attach to cells by binding to special sugar chains. One of these chains is characterised in that it has a monosaccharide known as sialic acid at its end. The thesis also shows that the virus binds to such sugar chains even when they are not part of the cell surface. This means that it may be possible for the sugar chains to prevent the virus infecting the cells by blocking its binding structures.
"Our results suggest that the sugar chains that have sialic acid are important for infection by the virus, but this must be confirmed. If it is true, it would be possible to develop a drug that blocks the access of the virus to the sugar molecule. One thing that we must investigate first, however, is whether there are other target molecules that the virus can use to enter the cell. These may be the starting point for even more effective drugs", says Gustaf Rydell.
Noroviruses are considered to be the micro-organism that causes the greatest incidence of vomiting and diarrhoea in the world. The viruses are responsible for approximately 200,000 child deaths in developing countries each year. Development of pharmaceuticals is made difficult by the fact that new virus strains arise continuously. One fifth of the population of Europe are "secretor negative" individuals, and these people have an inherited resistance to noroviruses.
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