Packaging of hepatitis delta virus RNA via the RNA-binding domain of hepatitis delta antigens: different roles for the small and large delta antigens.
Hepatitis delta virus (HDV) is composed of four specific components. The first component is envelope protein which contains hepatitis B surface antigens. The second and third components are nucleocapsid proteins, referred to as small and large hepatitis delta antigens (HDAgs). The final component is a single-stranded circular RNA molecule known as the viral genome. In order to study the mechanism of HDV RNA packaging, a four-plasmid cotransfection system in which each viral component was provided by a separate plasmid was employed. Virus-like particles released from Huh-7 cells receiving such a cotransfection were found to contain HDV RNA along with three proteins. Therefore, the four-plasmid cotransfection system could lead to successful HDV RNA packaging in vitro. The system was then used to show that the large HDAg alone was able to achieve a low level of HDV RNA packaging. Analysis of a variety of large HDAg mutants revealed that the RNA-binding domain was essential for viral RNA packaging. By increasing the incorporation of small HDAg into virus-like particles, we found a three- to fourfold enhancement of HDV RNA packaging. This effect was probably through a direct binding of HDV RNA, independent from that of large HDAg, with the small HDAg. The subsequent RNA-protein complex was packaged into particles. The results provided insight into the roles and functional domains of small and large HDAgs in HDV RNA packaging.
Wang
H W
HW
Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei.
Chen
P J
PJ
Lee
C Z
CZ
Wu
H L
HL
Chen
D S
DS
D000956:Antigens, Viral / Q000302:isolation & purification / Q000378:metabolism*; D015152:Blotting, Northern; D002460:Cell Line; D002499:Centrifugation, Density Gradient; D004279:DNA, Viral / Q000302:isolation & purification / Q000378:metabolism*; D003673:Defective Viruses / Q000235:genetics / Q000378:metabolism; D016679:Genome, Viral; D003698:Hepatitis Delta Virus / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D035923:Hepatitis delta Antigens; D006801:Humans; D010957:Plasmids; D016601:RNA-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D015183:Restriction Mapping; D014162:Transfection; D014779:Virus Replication / Q000235:genetics
D000956:Antigens, Viral; D004279:DNA, Viral; D035923:Hepatitis delta Antigens; D016601:RNA-Binding Proteins; C442244:hepatitis delta virus large antigen