Biomedical subjects

C McQuain

Publications and source records attributed to C McQuain.

24 records · Page 2Linked to original sources

PubMed1990

Mature, cell-associated HN protein of Newcastle disease virus exists in two forms differentiated by posttranslational modifications.

Characterization of the posttranslational modifications of the mature, cell-associated hemagglutinin-neuraminidase (HN) protein of Newcastle disease virus (NDV) revealed that the HN protein exists in two forms differentiated by disulfide bonds and glycosylation. One form, HNa, contains intermolecular disulfide bonds and is endoglycosidase H partially resistant. The other form, HNb, is not linked by disulfide bonds and is endoglycosidase H sensitive. Both forms of the protein are modified with fucose indicating transport to the Golgi membranes. Both forms are detected at the cell surface by monoclonal antibody. Furthermore, both forms are transported to the cell surface with identical kinetics. HNa is incorporated into virions. HNb is not incorporated into virions and is presumably degraded. The cDNA derived from the HN gene was expressed from a retrovirus vector. The majority of the protein expressed was in the nonvirion-associated form b. Evidence is presented that the level of gene expression determines the ratio of the two forms of HN protein. At high levels of expression, the virion-associated form is favored while at low levels of expression the nonvirion-associated form is favored. The results presented have implications for persistent infections as well as expression of viral genes from different vectors.

Animals↗

PubMed1990

Retroviral expressed hemagglutinin-neuraminidase protein protects chickens from Newcastle disease virus induced disease.

The hemagglutinin-neuraminidase (HN) gene and the phosphoprotein (P) gene of Newcastle disease virus (NDV) were inserted into a replication competent avian leukosis virus vector. The expression of the HN gene from this vector in chick embryo cells has been previously reported. The P gene is also expressed from this vector in chick embryo cells. The retroviruses were used to immunize 4-week-old chickens. Birds receiving the virus containing the HN gene developed low levels of serum HI titers and NDV neutralization titers. Upon challenge, all birds vaccinated with the HN gene containing virus were protected from disease but not viral infection and replication. In contrast, birds immunized with the P gene containing retrovirus developed more severe clinical signs of disease earlier than birds receiving no immunization or retrovirus alone. The results obtained with the HN gene may have potential application to reducing disease due to NDV genetically engineered vaccines.

Animals↗

PubMed1988

The P protein and the nonstructural 38K and 29K proteins of Newcastle disease virus are derived from the same open reading frame.

The nucleotide sequence of cloned cDNA copies of the mRNA encoding the Newcastle disease virus (NDV), strain AV, phosphoprotein (P) was determined. The sequence of 1443 nucleotides contains one long open reading frame which could encode a protein with a molecular weight of 42,126, and two smaller open reading frames which could encode proteins with molecular weights of 11,178 and 13,935. Full-length cDNA clones were constructed in an SP6 vector, mRNA was transcribed in a cell-free system using the SP6 polymerase, and the mRNA was translated in a wheat germ cell-free extract. The P mRNA directed the synthesis of, primarily, four products. One, with a molecular weight of 53,000 Da, comigrated with authentic P protein made in infected cells and was precipitable with antisera with specificity for the NDV P protein. The other products of the cell-free reaction had molecular weights of 38,000, 29,000 and 12,000. The 29,000- and the 38,000-Da polypeptides were also precipitable with anti-P protein antibody. Using truncated cDNA clones, evidence is presented that the 38,000- and 29,000-Da proteins are derived from initiation at AUG triplets in the same reading frame as the P protein. Infected cells also contain these polypeptides which may be analogous to C proteins of other paramyxoviruses. Thus the NDV P protein mRNA is different than most other paramyxovirus P protein mRNAs which are translated in two different reading frames to yield the P and C proteins.

Amino Acid Sequence↗

PubMed1986

Identification of the sequence content of four polycistronic transcripts synthesized in Newcastle disease virus infected cells.

During infection, the Newcastle disease virus (NDV) genome is transcribed to produce 5 to 7 species of polycistronic messenger RNA (Wilde and Morrison, J. Virol. 51, 71-76) in addition to the well characterized monocistronic messenger RNA. To identify the specific sequences present in each of the polycistronic RNA species, cDNA clones generated by reverse transcription of NDV mRNAs were characterized and used as probes on Northern blots of total NDV cytoplasmic RNA. By this method, it was shown that four of these large RNA species are polycistronic transcripts containing sequences from two genes: one species contains nucleocapsid protein (NP) and phosphoprotein (P) gene sequences; another, P and membrane protein (M) gene sequences; another, M and fusion protein (F0) gene sequences; and another, F0 and hemagglutinin-neuraminidase protein (HN) gene sequences. The existence of these transcripts yields a transcription map order of NP, P, M, F0, HN. The remaining RNA bands may be composed of at least three different polycistronic transcripts, each of which represents transcription through three adjacent genes.

Animals↗

PubMed1985

Effects of salsalate (nonacetylated salicylate) and aspirin on serum prostaglandins in humans.

Prostaglandin E2 (PGE2), thromboxane B2 (TXB2), and salicylic acid were measured in blood samples from 10 healthy men after administration of antiinflammatory doses of aspirin (3.9 g/day) or salsalate (3.0 g/day). Each medication was given for 3 days, followed by an observation period of 13 days. Plasma salicylate concentrations were slightly, but generally insignificantly, higher during aspirin dosing, although both drugs produced salicylic acid levels in the antiinflammatory range. Serum levels of PGE2 and TXB2, which reflected synthesis of cyclo-oxygenase products by platelets, were minimally affected by salsalate but profoundly suppressed by aspirin. When medication was discontinued, the effects of salsalate on serum PGE2 and TXB2 were readily reversible within 36 h, whereas the recovery from aspirin was still incomplete after 13 days of observation. These results indicate that the two orally administered salicylates have differential effects on prostaglandin synthesis in platelets and may also differ in their therapeutic and adverse effects.

Adult↗

PubMed1977

Assembly of viral membranes. I. Association of vesicular stomatitis virus membrane proteins and membranes in a cell-free system.

We report here an in vitro system designed to study the interactions of vesicular stomatitis virus (VSV) proteins with cellular membranes. We have synthesized the VSV nucleocapsid (N) protein, nonstructural (NS) protein, glycoprotein (G protein), and membrane (M) protein in a wheat germ, cell-free, protein-synthesizing system directed by VSV 12 to 18S RNA. When incubated at low salt concentrations with purified cytoplasmic membranes derived from Chinese hamster ovary cells, the VSV M andG proteins bind to membranes, whereas the VSV N and NS proteins do not. The VSV M protein binds to membranes in low or high divalent cation concentrations, whereas binding of significant amounts of G protein requires at least 5 mM magnesium acetate concentrations.

Cell Line↗