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Sridhar S, Wu S, Situ J, Shun EHK, Li Z, Zhang AJX, Hui K, Fong CHY, Poon VKM, Chew NFS, Yip CCY, Chan WM, Cai JP, Yuen KY. A small animal model of chronic hepatitis E infection using immunocompromised rats. JHEP Rep 2022; 4:100546. [PMID: 36052220 PMCID: PMC9424580 DOI: 10.1016/j.jhepr.2022.100546] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 06/30/2022] [Accepted: 07/08/2022] [Indexed: 12/14/2022] Open
Abstract
Background & Aims HEV variants such as swine genotypes within Paslahepevirus species balayani (HEV-A) and rat HEV (Rocahepevirus ratti; HEV-C1) cause chronic hepatitis E in immunocompromised individuals. There are few reliable and accessible small animal models that accurately reflect chronic HEV infection. We aimed to develop an immunocompromised rat model of chronic hepatitis E infection. Methods In this animal model infection study, rats were immunosuppressed with a drug combination (prednisolone, tacrolimus, and mycophenolate mofetil) commonly taken by transplant recipients. Rats were challenged with human- and rat-derived HEV-C1 strains or a human-derived HEV-A strain. Viral load, liver function, liver histology, humoural, and cellular immune responses were monitored. Results A high-dose (HD) immunosuppressive regimen consistently prolonged human- and rat-derived HEV-C1 infection in rats (up to 12 weeks post infection) compared with transient infections in low-dose (LD) immunosuppressant-treated and immunocompetent (IC) rats. Mean HEV-C1 viral loads in stool, serum, and liver tissue were higher in HD regimen-treated rats than in LD or IC rats (p <0.05). Alanine aminotransferase elevation was observed in chronically infected rats, which was consistent with histological hepatitis and HEV-C1 antigen expression in liver tissue. None (0/6) of the HD regimen-treated, 5/6 LD regimen-treated, and 6/6 IC rats developed antibodies to HEV-C1 in species-specific immunoblots. Reversal of immunosuppression was associated with clearance of viraemia and restoration of HEV-C1-specific humoural and cellular immune responses in HD regimen-treated rats, mimicking patterns in treated patients with chronic hepatitis E. Viral load suppression was observed with i.p. ribavirin treatment. HD regimen-treated rats remained unsusceptible to HEV-A infection. Conclusions We developed a scalable immunosuppressed rat model of chronic hepatitis E that closely mimics this infection phenotype in transplant recipients. Lay summary Convenient small animal models are required for the study of chronic hepatitis E in humans. We developed an animal model of chronic hepatitis E by suppressing immune responses of rats with drugs commonly taken by humans as organ transplant rejection prophylaxis. This model closely mimicked features of chronic hepatitis E in humans. Chronic HEV infection is challenging to model with small animals. Rats can be immunocompromised by transplant rejection drugs taken by patients. This model supports chronic rat HEV infection robustly and consistently. Immunosuppression in this model is scalable, reversible, and responsive to ribavirin.
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Key Words
- ALT, alanine aminotransferase
- HD, high dose
- HEV
- HEV, hepatitis E virus
- HEV-A, Paslahepevirus balayani
- HEV-C1
- HEV-C1, Rocahepevirus ratti genotype 1
- IC, immunocompetent
- IFN-γ, interferon-γ
- Immunosuppression
- LD, low dose
- MMF, mycophenolate mofetil
- Orthohepevirus C
- PBS, phosphate buffered saline
- Rat hepatitis E
- Ribavirin
- Rocahepevirus ratti
- VTM, virus transport medium
- dpi, days post infection
- rRT-PCR, real-time reverse-transcription PCR
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Affiliation(s)
- Siddharth Sridhar
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.,State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Hong Kong, China.,Carol Yu Centre for Infection, The University of Hong Kong, Hong Kong, China
| | - Shusheng Wu
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Jianwen Situ
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Estie Hon-Kiu Shun
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Zhiyu Li
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Anna Jin-Xia Zhang
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Kyle Hui
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Carol Ho-Yan Fong
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Vincent Kwok-Man Poon
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Nicholas Foo-Siong Chew
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Cyril Chik-Yan Yip
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Wan-Mui Chan
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Jian-Piao Cai
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Kwok-Yung Yuen
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.,State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Hong Kong, China.,Carol Yu Centre for Infection, The University of Hong Kong, Hong Kong, China.,The Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The University of Hong Kong, Hong Kong, China
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