Porcine sapovirus replication is restricted by the type I interferon response in cell culture.

Myra Hosmillo,Rintaro Hiraide,Kyoung-Oh Cho,Jia Lu,Ian Goodfellow,Frédéric Sorgeloos

doi:10.1099/vir.0.071365-0

Myra Hosmillo, Rintaro Hiraide + Show 4 more

Open Access

https://doi.org/10.1099/vir.0.071365-0

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Abstract

Porcine sapovirus (PSaV) of the family Caliciviridae, is the only member of the genus Sapovirus with cell culture and reverse genetics systems. When combined with the piglet model, these approaches provide a system to understand the molecular basis of sapovirus pathogenesis. The replication of PSaV in cell culture is, however, restricted, displaying an absolute requirement for bile acids and producing lower levels of infectious virus than other caliciviruses. The effect of bile acids has previously been linked to a reduction in the signal transducer and activator of transcription (STAT1)-mediated signalling pathway. In the current study, we observed that even in the presence of bile acids, PSaV replication in cell culture was restricted by soluble factors produced from infected cells. This effect was at least partially due to secreted IFN because treatment of cells with recombinant porcine IFN-β resulted in significantly reduced viral replication. Moreover, IFN-mediated signalling pathways (IFN, STAT1 and the 2′,5′-oligoadenylate synthetase) were activated during PSaV infection. Characterization of PSaV growth in cell lines deficient in their ability to induce or respond to IFN showed a 100–150-fold increase in infectious virus production, indicating that the primary role of bile acids was not the inactivation of the innate immune response. Furthermore, the use of IFN-deficient cell lines enabled more efficient recovery of PSaV from cDNA constructs. Overall, the highly efficient cell culture and reverse genetics system established here for PSaV highlighted the key role of the innate immune response in the restriction of PSaV infection and should greatly facilitate further molecular studies on sapovirus host–cell interactions.

Highlights

Caliciviruses have emerged as important pathogens for both humans and animals
Porcine sapovirus (PSaV) is the only calicivirus that replicates in cell culture (Chang et al, 2004), is amenable to reverse genetics (Chang et al, 2005) and reproducibly causes diarrhoea in the natural immunocompetent host (Wang et al, 2006)
Based on the growing body of literature on the role of innate immune responses in controlling calicivirus replication in cell culture, we examined the sensitivity of porcine sapovirus (PSaV) to the type I IFN response as well as the ability of bovine viral diarrhoea virus (BVDV) NPro or parainfluenza virus type 5 (PIV5) V proteins to improve the replication of PSaV

Summary

Introduction

Within the family Caliciviridae, members of the genera Norovirus and Sapovirus are a significant cause of viral gastroenteritis in humans worldwide (Blanton et al, 2006). Despite their importance, no efficient cell culture system to study human caliciviruses has been established (Duizer et al, 2004). Porcine sapovirus (PSaV) is the only calicivirus that replicates in cell culture (Chang et al, 2004), is amenable to reverse genetics (Chang et al, 2005) and reproducibly causes diarrhoea in the natural immunocompetent host (Wang et al, 2006)

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