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

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.This research was supported by funding from the Wellcome Trust (Ref: WT097997MA), Biotechnology and Biological Sciences Research Council (Ref: BB/I012303/1) and the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning (NRF-2014R1A2A2A01004292). IG is a Wellcome senior fellow.This is the final version of the article. It first appeared from the Society for General Microbiology via http://dx.doi.org/10.1099/vir.0.071365-

Detection of Hepatitis E Virus Antibodies in Dogs in the United Kingdom.

Hepatitis E virus (HEV) genotypes 3 and 4 are zoonotic pathogens, with pigs predominantly implicated in disease transmission. The rapid rise in human cases in developed countries over the past decade indicates a change in epidemiology of HEV, and it has been suggested that additional animal species may be involved in transmission of infection. Multiple studies have identified contact with dogs as a risk factor for HEV infection in industrialised nations, and a low seroprevalence to HEV has previously been reported in dogs in low-income countries. In this study we aimed to evaluate the possibility that dogs are susceptible to HEV, and determine the frequency with which this occurs. Serum samples from UK dogs with and without hepatitis were screened for HEV-specific antibodies, and canine liver and stool samples were analysed by qPCR for the presence of HEV RNA. We describe evidence to show HEV infection occurs at low levels in dogs in the UK, but the strain of origin is undetermined. The low seroprevalence level of HEV in dogs implies the risk of zoonotic disease transmission is likely to be limited, but further investigations will be required to determine if HEV-infected dogs can transmit HEV to man.This project was made possible by a Wellcome Trust Vacation Scholarship to AM, and was supported by a PhD studentship from the Medical Research Council to SC, a Wellcome Trust Research Training Fellowship to NB (Ref: WT088619MA) and a Wellcome Trust Senior Fellowship to IG (Ref: WT097997MA).This is the final version of the article. It first appeared from PLOS via http://dx.doi.org/10.1371/journal.pone.012870

Western blot analysis of serum sample reactivity with HEV, vesivirus 2117 and human norovirus G1.1 VLPs.

<p>Three types of VLP were separated by SDS-PAGE. One gel was stained with Coomassie Blue to identify VLP protein at the expected molecular weight. Additional gels were used for western blotting with canine serum samples positive by ELISA for HEV (samples A and B). A pig serum sample (kind gift from S. Emerson) and a human serum sample known to be positive for anti-HEV antibody were used as a positive control for the HEV VLPs. Canine sample C, previously confirmed positive for anti-vesivirus antibody by ELISA, was used as a positive control for the vesivirus VLPs. Canine sample D was used as a negative control for all VLPs.</p

Anti-HEV antibody titres in positive canine serum samples.

<p>Positive canine serum samples were prepared in dilutions of 1:100, 1:200, 1:400, 1:800; 1:1600 and 1:3200 and used in an ELISA assay. The corrected OD450 was obtained by subtracting the background signal from the VLP coated well OD450 value. The positive threshold was determined by calculating the mean OD450 of buffer coated wells with the highest serum dilution, plus 3 standard deviations.</p