Monoclonal antibodies to the matrix protein of vesicular stomatitis virus (New Jersey serotype) and their effects on viral transcription

Biochemical and immunological evidence that the 11 kDa zinc-binding protein of lymphocytic choriomeningitis virus is a structural component of the virus

The completed sequence of the arenavirus, lymphocytic choriomeningitis virus, revealed a new gene encoding a small protein with a single zinc-binding domain. The cDNA for this gene has been expressed in E. coli to produce fusion protein that has been used to raise antisera. The antisera facilitated the positive identification of the p11 'Z' gene product as a structural component of the virion. A related arenavirus, Tacaribe, has a comparable p11 gene product. The abundance of the p11 Z protein relative to other virion components has been determined by metabolic labeling. Triton X-114 extraction and dimethyl suberimidate-HCl crosslinking indicate that the p11 Z protein is a hydrophobic protein associated with the nucleocapsid of the virion core.

Viral RNA polymerases

Recent progress in molecular biological techniques revealed that genomes of animal viruses are complex in structure, for example, with respect to the chemical nature (DNA or RNA), strandedness (double or single), genetic sense (positive or negative), circularity (circle or linear), and so on. In agreement with this complexity in the genome structure, the modes of transcription and replication are various among virus families. The purpose of this article is to review and bring up to date the literature on viral RNA polymerases involved in transcription of animal DNA viruses and in both transcription and replication of RNA viruses. This review shows that the viral RNA polymerases are complex in both structure and function, being composed of multiple subunits and carrying multiple functions. The functions exposed seem to be controlled through structural interconversion.

Mapping regions of the matrix protein of vesicular stomatitis virus which bind to ribonucleocapsids, liposomes, and monoclonal antibodies

The matrix (M) protein of vesicular stomatitis virus (VSV) appears to function as a bridge between the ribonucleocapsid (RNP) core and the envelope in assembly of the virion. Two such properties would necessitate at least one site for interaction with the nucleocapsid and one with the envelope. In this study M protein was found to mediate the in vitro binding to RNP cores of phospholipid vesicles, representing membrane structures. The M protein could bind initially to either the vesicles or the RNP cores to promote RNP-vesicle association. A trypsin-resistant fragment (MT) of M protein, missing the initial 43 amino acids from its amino terminus, reconstituted with acidic phospholipid vesicles with the same binding efficiency as did whole M protein, suggesting that the carboxy-terminal 81% retained those regions of the M protein which interact with a lipid bilayer. The MT protein, however, was considerably less efficient than intact M protein as an inhibitor of in vitro virus transcription; almost 2.5-fold more MT protein than intact M protein was required for 50% inhibition of VSV transcription, indicating that a site for interaction with the RNP core may have been lost. A monoclonal antibody which is able to reverse the in vitro inhibition of transcription by M protein did not react by immunoblotting with MT protein. Partial tryptic digests of the M protein probed with this monoclonal antibody indicated that epitope 1 lies between amino acid residues 18 and 43. This region appears to be a site that promotes interaction of the M protein with the RNP core of VSV. Monoclonal antibodies to epitopes 2 and 3, which exhibit some overlap in binding to M protein but do not reverse transcription inhibition, were mapped by cleavage with N-chlorosuccinimide at regions in a carboxy direction from epitope 1.