Two gastroenteritis outbreaks caused by GII Noroviruses: host susceptibility and HBGA phenotypes

Noroviruses (NoVs) cause epidemic acute gastroenteritis, in which histo-blood group antigens (HBGAs) may play an important role in the host susceptibility. To further explore this issue, two outbreaks of acute gastroenteritis caused by a GII.4 and a GII.3 NoV, respectively, in China in 2009 were studied. Stool and saliva samples from symptomatic patients and water samples from the outbreak facilities were collected. RT-PCR showed that 23 out of 33 (GII.4 outbreak) and 12 out of 13 (GII.3outbreak) stool samples were NoV positive. For the GII.4 outbreak the NoV sequences of stool and water samples were from an identical GII.4 strain, while the same GII.3 NoV sequences were found in five stool samples from the GII.3 outbreak. The HBGA phenotypes (A, B, Le(a), Le(b), Le(x), and Le(y)) of all saliva samples were determined, which revealed both secretors and nonsecretors in the symptomatic groups of the two outbreaks. In the GII.3 outbreak, type O individuals appeared less susceptible, while the type A may be more at risk of infection. However, No preference of HBGAs was observed in the GII.4 outbreak. The observation that nonsecretors were infected in both outbreaks differed from the previous results that nonsecretors are resistant to these two GII NoVs.