title: Characterization of self-assembled virus-like particles of rat hepatitis E virus generated by recombinant baculoviruses.
abstract: Hepatitis E virus (HEV) is a causative agent of hepatitis E. Recently, a novel hepatitis E-like virus was isolated from Norway rats in Germany. However, the antigenicity, pathogenicity and epidemiology of this virus are unclear because of the lack of a cell-culture system in which to grow it. In this study, an N-terminally truncated ORF2 protein was expressed in insect Tn5 cells using a recombinant baculovirus expression system and a large amount of 53 kDa protein was expressed and efficiently released into the supernatant. Electron microscopic analyses of the purified 53 kDa protein revealed that the protein self-assembled into two types of empty HEV-like particles (rat HEVLPs). The smaller rat HEVLPs were estimated to be 24 nm in diameter, which is similar to the size of genotype G1, G3 and G4 HEVLPs. The larger rat HEVLPs were estimated to measure 35 nm in diameter, which is similar to the size of native rat HEV particles. An ELISA to detect antibodies was established using rat HEVLPs as the antigens, which demonstrated that rat HEVLPs were cross-reactive with G1, G3 and G4 HEVs. Detection of IgG and IgM antibodies was performed by examination of 139 serum samples from wild rats trapped in Vietnam, and it was found that 20.9 % (29/139) and 3.6 % (5/139) of the samples were positive for IgG and IgM, respectively. In addition, rat HEV RNA was detected in one rat serum sample that was positive for IgM. These results indicated that rat HEV is widespread and is transmitted among wild rats.
authors.affiliation: Department of Virology II, National Institute of Infectious Diseases, Gakuen 4-7-1, Musashi-murayama, Tokyo 208-0011, Japan.
authors.forename: Tian-Cheng
authors.initials: TC
authors.lastname: Li
authors.affiliation: Department of Microbiology, Graduate School of Medicine, Hokkaido University, Kita-15, Nishi-7, Kita-ku, Sapporo 060-8638, Japan.
authors.forename: Kumiko
authors.initials: K
authors.lastname: Yoshimatsu
authors.affiliation: Department of Microbiology, Graduate School of Medicine, Hokkaido University, Kita-15, Nishi-7, Kita-ku, Sapporo 060-8638, Japan.
authors.forename: Shumpei P
authors.initials: SP
authors.lastname: Yasuda
authors.affiliation: Department of Microbiology, Graduate School of Medicine, Hokkaido University, Kita-15, Nishi-7, Kita-ku, Sapporo 060-8638, Japan.
authors.forename: Jiro
authors.initials: J
authors.lastname: Arikawa
authors.affiliation: Department of Microbiology, Graduate School of Medicine, Hokkaido University, Kita-15, Nishi-7, Kita-ku, Sapporo 060-8638, Japan.
authors.forename: Takaaki
authors.initials: T
authors.lastname: Koma
authors.affiliation: Department of Pathology, National Institute of Infectious Diseases, Gakuen 4-7-1, Musashi-murayama, Tokyo 208-0011, Japan.
authors.forename: Michiyo
authors.initials: M
authors.lastname: Kataoka
authors.affiliation: Division of Experimental Animals Research, National Institute of Infectious Diseases, Gakuen 4-7-1, Musashi-murayama, Tokyo 208-0011, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Ami
authors.affiliation: Department of Pathology, National Institute of Infectious Diseases, Gakuen 4-7-1, Musashi-murayama, Tokyo 208-0011, Japan.
authors.forename: Yuriko
authors.initials: Y
authors.lastname: Suzaki
authors.affiliation: National Institute of Hygiene and Epidemiology, Hanoi, Vietnam, No. 1 Yersin Street, Hai Ba Trung District, Hanoi, Vietnam.
authors.forename: Le Thi Quynh
authors.initials: LTQ
authors.lastname: Mai
authors.affiliation: National Institute of Hygiene and Epidemiology, Hanoi, Vietnam, No. 1 Yersin Street, Hai Ba Trung District, Hanoi, Vietnam.
authors.forename: Nguyen Thuy
authors.initials: NT
authors.lastname: Hoa
authors.affiliation: Center for Infectious Disease Research in Asia and Africa, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan.
authors.forename: Tetsu
authors.initials: T
authors.lastname: Yamashiro
authors.affiliation: Center of International Collaborative Research, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan.
authors.forename: Futoshi
authors.initials: F
authors.lastname: Hasebe
authors.affiliation: Research Collaboration Center on Emerging and Re-Emerging Infections, Building 10, National Institute of Health, Department of Medical Sciences, Ministry of Public Health, Tivanond 14 Road, Muang, Nonthaburi 11000, Thailand.
authors.forename: Naokazu
authors.initials: N
authors.lastname: Takeda
authors.affiliation: Department of Virology II, National Institute of Infectious Diseases, Gakuen 4-7-1, Musashi-murayama, Tokyo 208-0011, Japan.
authors.forename: Takaji
authors.initials: T
authors.lastname: Wakita
mesh_terms: D000818:Animals; D016367:Baculoviridae / Q000378:metabolism*; D015153:Blotting, Western; D036022:Capsid Proteins / Q000378:metabolism; D002460:Cell Line; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D015967:Gene Expression Regulation, Viral; D005858:Germany; D016751:Hepatitis E / Q000276:immunology / Q000821:virology; D016752:Hepatitis E virus / Q000235:genetics* / Q000302:isolation & purification / Q000502:physiology*; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D007313:Insecta / Q000166:cytology; D012367:RNA, Viral / Q000302:isolation & purification; D011817:Rabbits; D051381:Rats; D017208:Rats, Wistar; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D014744:Vietnam; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism; D019065:Virus Assembly
chemical_list: D036022:Capsid Proteins; D007074:Immunoglobulin G; D007075:Immunoglobulin M; C400971:ORF2 protein, Hepatitis E virus; D012367:RNA, Viral; D011994:Recombinant Proteins; D014764:Viral Proteins