Purpose: To use an alternative binding ligand (nucleic acid aptamer) to aid in discrimination of hNoV infectivity status as a function of heat treatment.
Methods: Virus-like particles (VLPs) of hNoV GII.2 were exposed to temperatures from 65°C to 80°C for various times. Capsid integrity was assessed based on binding ability to previously characterized ssDNA aptamers using an Enzyme-Linked Aptamer Sorbent Assay (ELASA). Transmission electron microscopy images of the treated capsids were produced for comparison.
Results: Treatment of VLPs at 70°C for 20 and 40 minutes produced reductions in ELASA signal intensities of 33.9 ± 4.9% and 71.9 ± 0.5%, respectively. At 72°C, signal intensity reductions of 59.6 ± 2.5% and 74.0 ± 0.3% were observed after 10 and 20 minutes of heat, respectively. Treatments of 75°C and 80°C for one minute resulted in 45.1 ± 4.8% and 81.8 ± 6.1% loss of ELASA signal intensity. Signal intensities at different selected temperatures for most selected time points were statistically significantly different (P < 0.01). These results were supported by TEM, which showed VLP morphology alteration at similar temperatures.
Significance: Reduction in ELASA signal intensity corresponded with increased time-temperature exposures of hNoV VLPs, suggesting that aptamer binding may be a cheaper, readily-accessible alternative to other virus-specific ligands (antibodies, histo-blood group antigens) used for discriminating hNoV infectivity. Studies are underway to determine zD values using aptamer binding in conjunction with RT-qPCR.