Researchers from Nanjing Normal University (NNU) have made important breakthroughs in the research of the origin of hepatitis B viruses. They provide unique insights into the origin and evolution of hepadnaviruses by discovering HEART retroelements.
The paper entitled “Insect retroelements provide novel insights into the origin of hepatitis B viruses” was published in the Journal Molecular Biology and Evolution on June 19, 2018. NNU postgraduate Zhen Gong is the lead author of this paper, and NNU Prof. Guanzhu Han is the corresponding author.
Hepatitis B virus (HBV) is a species of the genus Orthohepadnavirus and a member of the Hepadnaviridae family of viruses. It infects at least 200 million people worldwide and kills 800,000 people a year. However, the origin of hepadnaviruses (Hepadnaviridae), a group of reverse-transcribing DNA viruses that infect vertebrates, remains mysterious. All the known retrotransposons are only distantly related to hepadnaviruses.
To solve this problem, a research group led by Prof. Guanzhu Han of the School of Life Sciences, NNU has made numerous efforts. They report the discovery of two novel lineages of retroelements, which they designate hepadnavirus-like retroelement (HEART1 and HEART2), within the insect genomes through screening 1,095 eukaryotic genomes. Both phylogenetic and similarity analyses suggest that the HEART retroelements represent the closest non-viral relatives of hepadnaviruses so far. The discovery of HEART retroelements narrows down the evolutionary gap between hepadnaviruses and retrotransposons and might thus provide unique insights into the origin and evolution of hepadnaviruses.
Support for the project was provided by the National Natural Science Foundation of China, the Natural Science Foundation of Jiangsu Province, and the Priority Academic Program Development of Jiangsu Higher Education Institutions.