TUESDAY, Feb. 12 (HealthDay News) -- It may be possible to
develop a vaccine to control noroviruses -- a common cause of
stomach flu -- but it's likely a such a vaccine would have to be
changed every year because the viruses evolve quickly to avoid
attacks by the immune system, new research suggests.
Noroviruses infect cells after attaching to histo-blood group
antigens (HBGA), molecules located on the surface of cells. HBGAs
are a family of complex sugar molecules that exist in great variety
among humans, according to background information in the study in
the journal
PLoS Medicine.
Ralph Baric, of the University of North Carolina at Chapel Hill,
and his colleagues found this large variety of HBGAs contributes to
recurrence of norovirus outbreaks, even among people who have
previously been exposed to the virus and have developed antibodies
against it.
The researchers analyzed noroviruses that caused several
outbreaks and found that the viruses evolved to avoid attack by
immune system antibodies.
Over time, some of the norovirus strains developed a shape that
enabled them to bind other forms of HBGA. These viruses were then
resistant to previously existing antibodies and able to infect
cells carrying that particular form of HBGA. These viruses could
then cause a new outbreak, with the cycle repeating itself, the
researchers said.
Noroviruses, which can cause nausea, vomiting and diarrhea, are
highly contagious. Most people recover within a few days, but the
viruses can cause severe problems in very young and in old people.
There is no specific treatment for norovirus infection.
More information
The U.S. Centers for Disease Control and Prevention has more
about
noroviruses.
