Hepatitis E Virus: An Ongoing Enigma

Hepatitis E virus (HEV) is a small nonenveloped, single-stranded positive-sense RNA virus which was discovered by the Russian virologist Mikhail Balayan in 1983. It was reported that about 900 million of the worldwide population has been infected with HEV, 15–20 million were reported to have an on-going infection. HEV usually causes self-limiting acute infections which may be asymptomatic or mildly symptomatic, progressing to chronicity in immunocompromised individuals like organ transplant recipients, HIV and chronic liver disease patients. The maternal mortality rate is ~25% during the third trimester of pregnancy caused by HEV genotype 1. HEV genotype 1 and 2 infect humans whereas genotype 3 and 4 causes chronic infections in industrialized countries by the zoonotic transfer. Enzyme immunoassay and nucleic acid amplification tests are used for the detection of HEV infections. China has developed HEV vaccine (Hecolin) based on ORF2 protein of genotype 1 in 2010 which is not used worldwide. There is no specific drug approved by FDA for the treatment of HEV infection but ribavirin can be used for rapid virus clearance. Ribavirin treatment may be accompanied by some side effects which necessitates the study of new potential antiviral targets against HEV.