Evaluation of sensitivity and heat susceptibility of isolated human Sapovirus in the HuTu80 cells culture model.

Philippe Raymond, Canadian Food Inspection Agency

Philippe Raymond1, Marie-Maude Allen1, Roxanne Blain1, Émilie Larocque1, Hirotaka Takagi2, Judy Qiu3, Tomoichiro Oka 2,4. 1.Canadian Food Inspection Agency, Food Virology National Reference Centre, Saint-Hyacinthe Laboratory, 3400 Casavant Boulevard West, Saint-Hyacinthe, QC J2S 8E3, Canada. 2.National Institute of Infectious Diseases, Tokyo, Japan 3.Public Health Laboratory, Alberta Precision Laboratories, Edmonton, Canada 4.National Institute of Health Sciences, Kanagawa, Japan

Food & Environmental Virology-I (Food)

Sapoviruses (SaV) are increasingly recognized as an important cause of diarrhea in pediatric and geriatric populations. As similar to noroviruses, SaV infections occur via person-to-person contact, contaminated environments, contaminated food and water and via consumption of raw or undercooked shellfish. Methods are needed to evaluate the risk associated with the detection of SaV in food. Late passage HuTu80 cells were reported previously as an efficient method to culture SaV. We evaluated the sensitivity of the HuTu80 cell culture model using human SaV GI.1 from cell passaged virus (P2), and tested the HuTu80 cell capacity to differentiate heat inactivated SaV. The SaV GI.1 viral RNA titer increased to 8×108 gEq per well. The GI.1 LOD50 was estimated at 8×104gEq per well (CI95 2×104 to 3×105) and the LOD95 was estimated at 3×105 gEq per well (CI95 8×105 to 1×106). No SaV growth was detected with SaV GI.1 at the concentration of 7×106 when heat treated 30 min at 70oC, while non-treated SaV increased by 8 log (3 x 1012 gEq per well). These results are consistent with previous ones performed with SaV-positive stool filtrates. While additional assays are required to evaluate and/or optimized the cell culture assay turnaround time, and the impact of different inactivation temperatures or models, the HuTu80 cell culture model which was reproducible between different facilities is a promising approach to evaluate the infectivity of SaV detected in food.