Relation of the structure of cytoplasmic polyhedrosis virus and the synthesis of its messenger RNA.
Cytoplasmic polyhedrosis virus (CPV) was observed under an electron microscope using a combination of staining and shadowing methods. Projections, not only in positions horizontal to the grid but also vertical, were clearly visualized. When the particle was mildly disrupted with EDTA, genome dsRNA was released from a projection. If the particle was previously fixed with glutaraldehyde and then disrupted, dsRNA was released with a protein particle, which seemed to correspond to the base part of the projection. The protein particle was in most cases at the end of the strand, which sometimes takes a supercoiled structure. When CPV was incubated during mRNA synthesis, the protein particles appeared in various positions along the strands, and loop formations of dsRNA appeared. From these observations, we suggest that transcription in this virus particle proceeds as follows: genome dsRNA is transcribed by passing through the base part of the projection, where the enzymes for mRNA synthesis are located. A completed mRNA is released from the virion at the projection.
Yazaki
K
K
Hepatitis Division, Tokyo Metropolitan Institute of Medical Science, Honkomagome, Bunkyo-ku, Tokyo, 113, Japan.
Miura
K
K