Pathology caused by persistent murine norovirus infection.
Subclinical infection of murine norovirus (MNV) was detected in a mixed breeding group of WT and Stat1(-/-) mice with no outward evidence of morbidity or mortality. Investigations revealed the presence of an attenuated MNV variant that did not cause cytopathic effects in RAW264.7 cells or death in Stat1(-/-) mice. Histopathological analysis of tissues from WT, heterozygous and Stat1(-/-) mice revealed a surprising spectrum of lesions. An infectious molecular clone was derived directly from faeces (MNV-O7) and the sequence analysis confirmed it was a member of norovirus genogroup V. Experimental infection with MNV-O7 induced a subclinical infection with no weight loss in Stat1(-/-) or WT mice, and recapitulated the clinical and pathological picture of the naturally infected colony. Unexpectedly, by day 54 post-infection, 50 % of Stat1(-/-) mice had cleared MNV-O7. In contrast, all WT mice remained infected persistently. Most significantly, this was associated with liver lesions in all the subclinically infected WT mice. These data confirmed that long-term persistence in WT mice is established with specific variants of MNV and that despite a subclinical presentation, active foci of acute inflammation persist within the liver. The data also showed that STAT1-dependent responses are not required to protect mice from lethal infection with all strains of MNV.
Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 OES, UK.
Amita
A
Shortland
Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 OES, UK.
James
J
Chettle
Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 OES, UK.
Joy
J
Archer
Nuffield Department of Surgical Sciences, University of Oxford, Level 6, John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK.
Kathryn
K
Wood
Institute of Biomedical Research, University of Birmingham, Birmingham B15 2TT, UK.
Dalan
D
Bailey
Division of Virology, Department of Pathology, University of Cambridge, Addenbrooke's Hospital Level 5, Hills Road, Cambridge CB2 2QQ, UK.
Ian
I
Goodfellow
Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 OES, UK.
Barbara A
BA
Blacklaws
Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 OES, UK.
Jonathan L
JL
Heeney
D000825:Animal Structures / Q000473:pathology*; D000818:Animals; D058345:Asymptomatic Infections; D017250:Caliciviridae Infections / Q000473:pathology* / Q000821:virology*; D002460:Cell Line; D003588:Cytopathogenic Effect, Viral; D006651:Histocytochemistry; D008264:Macrophages / Q000821:virology; D051379:Mice; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D029322:Norovirus / Q000302:isolation & purification*; D012367:RNA, Viral / Q000737:chemistry / Q000235:genetics; D050794:STAT1 Transcription Factor / Q000172:deficiency / Q000235:genetics; D017422:Sequence Analysis, DNA
D012367:RNA, Viral; D050794:STAT1 Transcription Factor; C494080:Stat1 protein, mouse