Vaccinia virus replication. I. Requirement for the host-cell nucleus

Area of Science:

• Virology
• Cell Biology
• Molecular Biology

Background:

• Vaccinia virus is a large DNA virus with a complex replication cycle.
• The role of the host-cell nucleus in vaccinia virus replication has been investigated.

Purpose of the Study:

• To determine if vaccinia virus can replicate in the absence of the host-cell nucleus.
• To elucidate the specific nuclear functions required for vaccinia virus maturation and progeny production.

Main Methods:

• Enucleation of mammalian cell lines (BSC-40, CVC, L) using cytochalasin B.
• Analysis of viral protein synthesis, DNA synthesis, and morphogenesis in infected cytoplasts.
• Electron microscopy and radiolabeling techniques were employed.

Main Results:

• Infected enucleated cells (cytoplasts) failed to produce infectious vaccinia virus progeny.
• Viral gene expression and cytoplasmic DNA synthesis occurred in cytoplasts, but DNA did not become DNase-resistant.
• Morphogenesis was incomplete in cytoplasts, with no DNA condensation or particle maturation observed.

Conclusions:

• The host-cell nucleus is essential for the proper maturation and infectious progeny production of vaccinia virus.
• While early viral replication steps occur in the cytoplasm, a nuclear factor or function is indispensable for late-stage development.