Kirsten Mattison

Stool specimens were collected from 100 children in Botswana. RT-PCR analysis detected noroviruses (NoVs) in 24% of samples tested. Genogroup I and genogroup II strains were identified. There was no association between NoV detection and age or gender. This study is the first indication that NoVs circulate widely in Botswana. J. Med. Virol. 82:321–324, 2010.

Point source norovirus outbreaks can be difficult to track due to high background levels of the virus in the environment and the limited strain variation in some genotyping regions. However, rapid and accurate source identification can limit the spread of a foodborne outbreak and reduce the number of cases. Harmonization of genotyping assays is critical for enabling the rapid exchange of sequence data nationally and internationally. Several regions of the genome have been proposed for this purpose, but no consensus has been reached. In the present study, two standardized genotyping protocols (region C and region D) were evaluated by nine laboratories in Canada and the United States, using a coded panel of 96 fecal specimens representing 22 different norovirus genotypes. Overall, region C typing had a success rate of 78% compared to 52% for region D; however, region D provides greater nucleotide sequence diversity for identifying new GII.4 variant strains. Significant differences in the genotyping success rate were observed among the nine participating laboratories (10% to 100%) and among the different genotypes (6% to 100%). For several genogroup II strains, reduced region D amplification correlated directly with mismatches between primer sequences and the template. Based on overall performance, we recommend the region C protocol for routine genotyping of noroviruses, while the region D protocol may be useful for identifying new GII.4 variants. Standardized genotyping protocols will enable rapid exchange of outbreak and sequence data through electronic norovirus surveillance networks.

This study used histo-blood group antigen-conjugated beads to detect norovirus (NoV) in contaminated strawberries, green onions, lettuce, and deli ham. In addition, multiple strains of NoV from genogroups I and II were recovered. This provides an effective protocol for food testing in the investigation of suspected NoV outbreaks.

Human noroviruses are the predominant cause of foodborne gastroenteritis worldwide. Strains of norovirus also exist that are uniquely associated with animals; their contribution to the incidence of human illness remains unclear. We tested animal fecal samples and identified GIII (bovine), GII.18 (swine), and GII.4 (human) norovirus sequences, demonstrating for the first time, to our knowledge, that GII.4-like strains can be present in livestock. In addition, we detected GII.4-like noroviral RNA from a retail meat sample. This finding highlights a possible route for indirect zoonotic transmission of noroviruses through the food chain.