Thermal inactivation of infectious hepatitis E virus in experimentally contaminated food

Abstract

Hepatitis E virus (HEV) infection of zoonotic origin is an emerging concern in industrialized countries. In the past few years, several cases of zoonotic hepatitis E have been identified and the consumption of food products derived from pork liver have been associated with clusters of human cases. More specifically, raw or undercooked pork products have been incriminated. Few data on the effect of heating on HEV inactivation in food products are available. In the present study, the various times and temperatures that are used during industrial processing of pork products were applied to experimentally contaminated food preparations. After treatment, the presence of residual infectious virus particles was investigated using real-time reverse transcription-PCR and an in vivo experimental model in pigs. Results show that heating the food to an internal temperature of 71°C for 20 min is necessary to completely inactivate HEV. These results are very important for determining processing methods to ensure food safety in regard to food-borne hepatitis E.

FIG 1

Monitoring of internal temperature of the pâté-like preparation. For each temperature, a thermal sensor was used to measure the internal temperature of samples consisting of a control pâté-like preparation made with noninfected pork liver. For a given temperature, all samples were immersed simultaneously and then removed sequentially at the chosen duration of incubation. (A) 62°C; (B) 68°C; (C) 71°C.

FIG 2

Time course of seroconversion to anti-HEV antibodies in SPF pigs inoculated with the viral suspensions made from the pâté-like preparation after different time/temperature treatments. In each panel, the temperature and duration of incubation of the administered prepared suspensions (one color per duration) are indicated for each pig, along with its identification number (different symbol for each pig in each group).