Molecular features of Hepatitis E Virus circulation in environmental and human samples

Area of Science:

• Virology
• Environmental Health
• Molecular Biology

Background:

• Hepatitis E virus (HEV) is an emerging pathogen with poorly understood human-environmental circulation.
• The HEV ORF2 gene encodes the capsid protein, crucial for viral surface interactions, while ORF3 products are vital for the viral life cycle.

Purpose of the Study:

• To investigate the molecular characteristics of HEV ORF2 and ORF3 genes.
• To understand how these molecular features contribute to HEV fitness in patients and the environment.

Main Methods:

• Analysis of HEV strains from patients, urban wastewater, a pig slaughterhouse, farm pigs, and wild boars.
• Direct sequencing of HEV ORF2 M region and ORF2/ORF3 genes.
• Phylogenetic analysis, physicochemical prediction, and ultra-deep sequencing of HEV ORF2.

Main Results:

• HEV genotype 3 was frequently detected across all sample types, including human, animal, and environmental sources.
• HEV quasispecies showed a dominant viral variant in ORF2, with minor mutations affecting predicted antigenicity.
• A distinct cysteine signature at position 81 in ORF3 was identified in boar HEV strains.

Conclusions:

• HEV genotype 3 demonstrates circulation among humans, animals, and environmental matrices like wastewater.
• Low amino acid variability in the HEV ORF2 M region and specific ORF2/ORF3 molecular features suggest enhanced viral fitness and adaptability.