Interactions between human norovirus virus-like particles and bacteria: Impact on thermal resistance

Human norovirus, a leading cause of foodborne gastroenteritis, is known for the virus’s resistance to inactivation and environmental persistence. It interacts with histo-blood group antigens, its only known ligands. Due to the lack of an efficient cell culture system, noninfectious virus-like particles (VLPs) are used for research. This study aimed to identify virus-microbe pairs, characterize their interactions, and assess their effects on bacterial heat resistance. VLPs of genotypes GII.4 and GII.17 were tested against 77 microbial strains, including 44 pathogenic bacteria, 4 fermentative bacteria, and 6 yeasts.. Specific interactions were observed between GII.17 VLPs and Staphylococcus aureus or Enterobacter cloacae , mediated by surface sugar-dependent mechanisms confirmed by sodium periodate treatment. No binding was detected with GII.4 VLPs. Competition assays suggested that histo-blood group antigen-like structures were not involved. Atomic force microscopy revealed direct attachment of VLPs within the exopolysaccharide matrix of E. cloacae . Environmental factors significantly affected binding efficiency. It was influenced by buffer composition, increasing in citrate buffer, and by oxygen availability, being abolished under anaerobic conditions. Furthermore, attached particles enhanced bacterial heat resistance. These findings provide new insight into norovirus persistence and virulence, particularly for genotype GII.17, which, though less prevalent, exhibits stronger binding affinity.