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Situ J, Hon-Yin Lo K, Cai JP, Li Z, Wu S, Hon-Kiu Shun E, Foo-Siong Chew N, Yiu-Hung Tsoi J, Sze-Man Chan G, Hei-Man Chan W, Chik-Yan Yip C, Sze KH, Chi-Chung Cheng V, Yuen KY, Sridhar S. An immunoassay system to investigate epidemiology of Rocahepevirus ratti (rat hepatitis E virus) infection in humans. JHEP Rep 2023; 5:100793. [PMID: 37575885 PMCID: PMC10415708 DOI: 10.1016/j.jhepr.2023.100793] [Citation(s) in RCA: 3] [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: 08/25/2022] [Revised: 03/23/2023] [Accepted: 04/14/2023] [Indexed: 08/15/2023] Open
Abstract
Background & Aims Rat hepatitis E virus (Rocahepevirus ratti; HEV-C1) is an emerging cause of hepatitis E that is divergent from conventional human-infecting HEV variants (Paslahepevirus balayani; HEV-A). Validated serological assays for HEV-C1 are lacking. We aimed to develop a parallel enzymatic immunoassay (EIA) system that identifies individuals with HEV-C1 exposure. We also aimed to conduct the first HEV-C1 seroprevalence study in humans using this validated EIA system. Methods Expressed HEV-A (HEV-A4 p239) and HEV-C1 (HEV-C1 p241) peptides were characterised. Blood samples were simultaneously tested in HEV-A4 p239 and HEV-C1 p241 IgG EIAs. An optical density (OD) cut-off-based interpretation algorithm for identifying samples seropositive for HEV-A or HEV-C1 was validated using RT-PCR-positive infection sera. This algorithm was used to measure HEV-C1 seroprevalence in 599 solid organ transplant recipients and 599 age-matched immunocompetent individuals. Results Both peptides formed virus-like particles. When run in HEV-A4 p239 and HEV-C1 p241 EIAs, HEV-A and HEV-C1 RT-PCR-positive samples formed distinct clusters with minimal overlap in a two-dimensional plot of optical density values. The final EIA interpretation algorithm showed high agreement with RT-PCR results (Cohen's κ = 0.959) and was able to differentiate HEV-A and HEV-C1 infection sera with an accuracy of 94.2% (95% CI: 85.8-98.4%). HEV-C1 IgG seroprevalence was 7/599 (1.2%) among solid organ transplant recipients and 4/599 (0.7%) among immunocompetent individuals. Five of 11 (45.5%) of these patients had history of transient hepatitis of unknown cause. Conclusions HEV-C1 exposure was identified in 11/1198 (0.92%) individuals in Hong Kong indicating endemic exposure. This is the first estimate of HEV-C1 seroprevalence in humans. The parallel IgG EIA algorithm is a valuable tool for investigating epidemiology and risk factors for HEV-C1 infection. Impact and Implications Rat hepatitis E virus has recently been discovered to infect humans, but antibody tests for this infection are lacking, making it difficult to gauge how common this infection is. We developed an antibody test algorithm that can identify individuals with past rat hepatitis E virus exposure. We used this algorithm to estimate rat hepatitis E exposure rates in humans in Hong Kong and found that approximately 1% of all tested people had been exposed to this virus previously.
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Affiliation(s)
- Jianwen Situ
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Kelvin Hon-Yin Lo
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Jian-Piao Cai
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Zhiyu Li
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Shusheng Wu
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, 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, Pokfulam, 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, Pokfulam, Hong Kong, China
| | - James Yiu-Hung Tsoi
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Gabriel Sze-Man Chan
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Winson Hei-Man Chan
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, 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, Pokfulam, Hong Kong, China
| | - Kong Hung Sze
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Vincent Chi-Chung Cheng
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Kwok-Yung Yuen
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, 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
- Centre for Virology, Vaccinology and Therapeutics, Hong Kong Science and Technology Park, Hong Kong Special Administrative Region, Hong Kong, China
| | - Siddharth Sridhar
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, 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
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