The Open Reading Frame 4 Region of Hepatitis E Virus - A Brief Introduction

Hepatitis E virus (HEV) is a small virus belonging to the family Hepeviridae. The genome of HEV is a single-stranded, positive-sense RNA about 15 kb in length and is categorized into three open reading frames (ORFs): ORF1 (replicative machinery), ORF2 (viral capsid) essential for (infectious particle formation) and ORF3 (viral release), encoding both structural and non-structural proteins. The fourth ORF4 has been demonstrated to play a critical role in the viral replication in genotype 1 (GT 1) isolates of HEV. Due to insufficiency in appropriate HEV in vitro cell culture systems, our knowledge of its pathogenesis is inadequately understood. The current introductory chapter briefly focuses on the novel ORF4 along with its functions known to date based on the newest published literature. The information provided in this review on the HEV ORF4 protein is likely to assist in understanding the deeper functioning of HEV biology.