title: Endoplasmic Reticulum Stress Induced Synthesis of a Novel Viral Factor Mediates Efficient Replication of Genotype-1 Hepatitis E Virus.
abstract: Hepatitis E virus (HEV) causes acute hepatitis in many parts of the world including Asia, Africa and Latin America. Though self-limiting in normal individuals, it results in ~30% mortality in infected pregnant women. It has also been reported to cause acute and chronic hepatitis in organ transplant patients. Of the seven viral genotypes, genotype-1 virus infects humans and is a major public health concern in South Asian countries. Sporadic cases of genotype-3 and 4 infection in human and animals such as pigs, deer, mongeese have been reported primarily from industrialized countries. Genotype-5, 6 and 7 viruses are known to infect animals such as wild boar and camel, respectively. Genotype-3 and 4 viruses have been successfully propagated in the laboratory in mammalian cell culture. However, genotype-1 virus replicates poorly in mammalian cell culture and no other efficient model exists to study its life cycle. Here, we report that endoplasmic reticulum (ER) stress promotes genotype-1 HEV replication by inducing cap-independent, internal initiation mediated translation of a novel viral protein (named ORF4). Importantly, ORF4 expression and stimulatory effect of ER stress inducers on viral replication is specific to genotype-1. ORF4 protein sequence is mostly conserved among genotype-1 HEV isolates and ORF4 specific antibodies were detected in genotype-1 HEV patient serum. ORF4 interacted with multiple viral and host proteins and assembled a protein complex consisting of viral helicase, RNA dependent RNA polymerase (RdRp), X, host eEF1α1 (eukaryotic elongation factor 1 isoform-1) and tubulinβ. In association with eEF1α1, ORF4 stimulated viral RdRp activity. Furthermore, human hepatoma cells that stably express ORF4 or engineered proteasome resistant ORF4 mutant genome permitted enhanced viral replication. These findings reveal a positive role of ER stress in promoting genotype-1 HEV replication and pave the way towards development of an efficient model of the virus.
authors.affiliation: Virology Laboratory, Vaccine and Infectious Disease Research Centre, Translational Health Science and Technology Institute, NCR Biotech Science Cluster, Faridabad, Haryana, India.
authors.forename: Vidya P
authors.initials: VP
authors.lastname: Nair
authors.affiliation: Virology Laboratory, Vaccine and Infectious Disease Research Centre, Translational Health Science and Technology Institute, NCR Biotech Science Cluster, Faridabad, Haryana, India.
authors.forename: Saumya
authors.initials: S
authors.lastname: Anang
authors.affiliation: Virology Laboratory, Vaccine and Infectious Disease Research Centre, Translational Health Science and Technology Institute, NCR Biotech Science Cluster, Faridabad, Haryana, India.
authors.forename: Chandru
authors.initials: C
authors.lastname: Subramani
authors.affiliation: Virology Laboratory, Vaccine and Infectious Disease Research Centre, Translational Health Science and Technology Institute, NCR Biotech Science Cluster, Faridabad, Haryana, India.
authors.forename: Abhilasha
authors.initials: A
authors.lastname: Madhvi
authors.affiliation: Virology Laboratory, Vaccine and Infectious Disease Research Centre, Translational Health Science and Technology Institute, NCR Biotech Science Cluster, Faridabad, Haryana, India.
authors.forename: Karishma
authors.initials: K
authors.lastname: Bakshi
authors.affiliation: Virology Laboratory, Vaccine and Infectious Disease Research Centre, Translational Health Science and Technology Institute, NCR Biotech Science Cluster, Faridabad, Haryana, India.
authors.forename: Akriti
authors.initials: A
authors.lastname: Srivastava
authors.affiliation: Department of Gastroenterology, All India Institute of Medical Sciences, Gautam Nagar, Ansari Nagar East, New Delhi, Delhi, India.
authors.lastname: Shalimar
authors.affiliation: Department of Gastroenterology, All India Institute of Medical Sciences, Gautam Nagar, Ansari Nagar East, New Delhi, Delhi, India.
authors.forename: Baibaswata
authors.initials: B
authors.lastname: Nayak
authors.affiliation: Virology Laboratory, Vaccine and Infectious Disease Research Centre, Translational Health Science and Technology Institute, NCR Biotech Science Cluster, Faridabad, Haryana, India.
authors.forename: C T
authors.initials: CT
authors.lastname: Ranjith Kumar
authors.affiliation: Virology Laboratory, Vaccine and Infectious Disease Research Centre, Translational Health Science and Technology Institute, NCR Biotech Science Cluster, Faridabad, Haryana, India.
authors.forename: Milan
authors.initials: M
authors.lastname: Surjit
mesh_terms: D002478:Cells, Cultured; D004261:DNA Replication / Q000235:genetics*; D059865:Endoplasmic Reticulum Stress / Q000235:genetics*; D005838:Genotype; D016752:Hepatitis E virus / Q000502:physiology*; D006801:Humans; D012367:RNA, Viral / Q000235:genetics*; D012324:RNA-Dependent RNA Polymerase / Q000235:genetics; D014764:Viral Proteins / Q000235:genetics; D014779:Virus Replication / Q000235:genetics*
chemical_list: D012367:RNA, Viral; D014764:Viral Proteins; D012324:RNA-Dependent RNA Polymerase