Assembly of viral particles in Xenopus oocytes: pre-surface-antigens regulate secretion of the hepatitis B viral surface envelope particle.
Infection with hepatitis B virus (HBV) is associated with the production of a viral envelope particle that contains membrane lipids, surface antigen (S), and two presurface-antigens (pre-S) comprised of the entire S moiety with approximately 55 (pre-S2) and 174 (pre-S1) additional NH2-terminal amino acids. We show here that Xenopus oocytes injected with synthetic S mRNA assemble and secrete characteristic 22-nm viral envelope particles. In contrast, pre-S1 and pre-S2 antigens are synthesized but not secreted. By coinjecting mRNAs, we found that synthesis of high levels of pre-S proteins specifically inhibits S antigen secretion. On the other hand, high levels of S synthesis can drive the secretion of small amounts of either pre-S antigen. These observations are consistent with a model for viral envelope assembly in which both S and pre-S proteins are incorporated into a multimeric particle, presumably via interactions between the S protein domains, while the pre-S amino-terminal moieties regulate the secretion of this structure. Our results indicate that Xenopus oocytes will provide a powerful system for studying the morphogenesis of simple structures of viral or cellular origin.
Standring
D N
DN
Ou
J H
JH
Rutter
W J
WJ
D000818:Animals; D006514:Hepatitis B Surface Antigens / Q000502:physiology*; D006515:Hepatitis B virus / Q000235:genetics / Q000254:growth & development* / Q000648:ultrastructure; D008970:Molecular Weight; D009024:Morphogenesis; D011498:Protein Precursors / Q000235:genetics; D014759:Viral Envelope Proteins / Q000502:physiology*; D014982:Xenopus laevis / Q000235:genetics
D006514:Hepatitis B Surface Antigens; D011498:Protein Precursors; D014759:Viral Envelope Proteins