Characterization of a prototype strain of hepatitis E virus

Area of Science:

• Virology
• Hepatology
• Molecular Biology

Background:

• Hepatitis E is an enterically transmitted disease, previously known as non-A, non-B hepatitis.
• The hepatitis E virus (HEV) SAR-55 strain was linked to a significant epidemic.

Purpose of the Study:

• To extensively characterize the HEV SAR-55 strain.
• To investigate viral shedding patterns and antibody induction in infected primates.
• To sequence and analyze the HEV SAR-55 genome and compare it with other strains.

Main Methods:

• Infection of six cynomolgus monkeys (Macaca fascicularis) with the HEV Pakistan strain (SAR-55).
• Reverse transcription-polymerase chain reaction (RT-PCR) to monitor virus shedding in feces, bile, and serum.
• Full genome sequencing of the SAR-55 strain (7195 nucleotides).
• Comparative sequence analysis with a Burmese HEV strain and partial sequencing of a Kirgiz isolate.

Main Results:

• HEV shedding patterns and antibody induction were documented in infected monkeys.
• The complete genome of the SAR-55 strain was sequenced.
• High homology was observed between SAR-55 and the Burmese strain, except for a 100-amino acid region in a nonstructural polyprotein.
• This specific region was identified as hypervariable through analysis of a third HEV isolate.

Conclusions:

• The HEV SAR-55 strain possesses a hypervariable genomic region, crucial for understanding HEV diversity.
• This variability may play a role in HEV evolution and the virus's ability to evade immune responses.
• Further research into this hypervariable region can inform diagnostic and therapeutic strategies for Hepatitis E.