Purpose: To characterize the binding affinity of select bacterial isolates to representative HuNoV strains.
Methods: Sixteen bacterial isolates (5 ATCC strains; 11 fecal isolates obtained from HuNoV-positive stool samples) were used in this study. Isolates were grown anaerobically, exposed to HuNoV GII.4 New Orleans, GI.6, or the Tulane virus surrogate, and then pelleted. To characterize binding affinity, the pellet and supernatant were separately subjected to RNA extraction and RT-qPCR. Turnip Crinkle Virus (TCV), a plant virus with similar size and structure to HuNoV, was used as a negative control. The three bacterial strains showing the highest binding affinity to HuNoV GII.4 were chosen for additional ELISA-based studies to determine evidence of histo-blood group antigen (HBGA)-like molecules corresponding to ABH, Lewis A, Lewis B, Lewis Y and H type 1.
Results: When cultured in tryptic soy broth (TSB), all bacteria tested exhibited a high level of binding to GII.4 New Orleans (89.62 ± 4.95% capture efficiency). Only bacteria incapable of growing in TSB, including Bacteroides thetaiotaomicron (chopped meat media), Lactobacillus gasseri and L. plantarum (MRS broth), showed a significantly lower level of binding (45.47 ± 12.0% capture efficiency). This interaction was specific, as there were different bacterial binding patterns for GI.6 and Tulane viruses; no binding was observed for TCV. Only one fecal isolate showed HBGA activity, with possible Lewis A and ABH-like motifs present.
Significance: Preliminary data suggests HuNoV bind a range of bacteria in a strain specific manner, and the ligand responsible for this interaction may not be exclusively HBGA-like moieties. These data have relevance in efforts to cultivate HuNoV and for methods to concentrate and purify HuNoV for downstream detection.