Hepatitis E virus chronic infection of swine co-infected with porcine reproductive and respiratory syndrome virus

Abstract

In developed countries, most of hepatitis E human cases are of zoonotic origin. Swine is a major hepatitis E virus (HEV) reservoir and foodborne transmissions after pork product consumption have been described. The risk for HEV-containing pig livers at slaughter time is related to the age at infection and to the virus shedding duration. Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) is a virus that impairs the immune response; it is highly prevalent in pig production areas and suspected to influence HEV infection dynamics. The impact of PRRSV on the features of HEV infections was studied through an experimental HEV/PRRSV co-infection of specific-pathogen-free (SPF) pigs. The follow-up of the co-infected animals showed that HEV shedding was delayed by a factor of 1-9 in co-infected pigs compared to HEV-only infected pigs and specific immune response was delayed by a factor of 1-6. HEV shedding was significantly increased with co-infection and dramatically extended (48-6 versus 9-7 days for HEV only). The long-term HEV shedding was significantly correlated with the delayed humoral response in co-infected pigs. Direct transmission rate was estimated to be 4-7 times higher in case of co-infection than in HEV only infected pigs (0-70 and 0-15 per day respectively). HEV infection susceptibility was increased by a factor of 3-3, showing the major impact of PRRSV infection on HEV dynamics. Finally, HEV/PRRSV co-infection - frequently observed in pig herds - may lead to chronic HEV infection which may dramatically increase the risk of pig livers containing HEV at slaughter time.