Biomedical subjects

M E Whealy

Publications and source records attributed to M E Whealy.

21 records · Page 2Linked to original sources

PubMed1986

Construction of an infectious pseudorabies virus recombinant expressing a glycoprotein gIII-beta-galactosidase fusion protein.

An infectious herpesvirus mutant has been constructed in which a major structural envelope glycoprotein gene was replaced by a hybrid gene encoding a novel fusion protein consisting of the N-terminus of the viral glycoprotein joined to Escherichia coli beta-galactosidase (beta Gal). Specifically, we fused DNA encoding the first 157 amino acids of the structural glycoprotein gIII from pseudorabies virus strain Becker to the E. coli lacZ gene in a bacterial expression vector. The resulting hybrid gene was then used to replace the wild-type gIII gene in the virus by cotransfection of plasmid and viral DNA. The desired viral recombinants were identified by their inability to react with specific monoclonal antibodies that recognized only wild-type gIII protein. One such mutant virus, PRV-Z1, was chosen for further analysis. PRV-Z1 expressed a glycosylated gIII-beta Gal fusion protein after infection of PK15 cells. The fusion protein has no demonstrable beta Gal activity and, although glycosylated, remains sensitive to the enzyme endo-beta-N-acetylglucosaminidase H, unlike the mature gIII gene product, indicating that the fusion protein was incompletely processed.

Antigens, Viral↗

PubMed1986

Characterization of a pseudorabies virus glycoprotein gene with homology to herpes simplex virus type 1 and type 2 glycoprotein C.

A pseudorabies virus (Becker strain) glycoprotein gene was located in the UL region at map position 0.40. The gene was identified by using open reading frame Escherichia coli plasmid expression vectors and specific antibody reagents. A 1.55-kilobase unspliced transcript from the gene was detected in pseudorabies virus-infected tissue culture cells. The DNA sequence revealed a single open reading frame of 1,437 base pairs encoding 479 amino acids. The predicted primary translation product has a molecular weight of 50,860 and contains features of a typical herpesvirus glycoprotein. An E. coli expression plasmid was constructed that contained essentially all of the open reading frame for this gene. Antibodies raised in rabbits against the protein expressed in bacteria by this plasmid immunoprecipitated pseudorabies virus-specific glycoproteins of 92,000 and 74,000 daltons from infected cell extracts. It is likely that these two forms represent different glycosylation states of the protein.

Cloning, Molecular↗

PubMed1986

Pseudorabies virus gene encoding glycoprotein gIII is not essential for growth in tissue culture.

We have established that in the Becker strain of pseudorabies virus (PRV), the glycoprotein gIII gene is not essential for growth in cell culture. This was accomplished by construction and analysis of viral mutants containing two defined deletion mutations affecting the gIII gene. These mutations were first constructed in vitro and introduced into Escherichia coli expression plasmids to verify structure and protein production. Each mutation was then crossed onto PRV by cotransfection of plasmid DNA and parental viral DNA by using gIII-specific monoclonal antibodies as selective and screening reagents. One resultant virus strain, PRV-2, contained an in-frame deletion of a 402-base-pair (bp) SacI fragment contained within the gIII gene. Another virus strain, PRV-10, contained a deletion of a 1,480-bp XhoI fragment removing 230 bp of the upstream, putative transcriptional control sequences and 87% of the gIII coding sequence. The deletion mutants were compared with parental virus by analysis of virion DNA, gIII specific RNA, and proteins reacting with gIII specific antibodies. Upon infection of PK15 cells, the deletion mutants did not produce any proteins that reacted with two gIII specific monoclonal antibodies. However, two species of truncated glycosylated proteins were observed in PRV-2 infected cells that reacted with antiserum raised against bacterially produced gIII protein. PRV-10 produced no detectable gIII-specific RNA or protein. PRV-10 could be propagated without difficulty in tissue culture. Virus particles lacking gIII were indistinguishable from parental PRV virus particles by analysis of infected-cell thin sections in the electron microscope. We therefore conclude that expression of the gIII gene was not absolutely essential for PRV growth in tissue culture.

Animals↗