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It has recently been shown that cowpea plants can be infected with a cowpea mosaic virus (CPMV) chimera containing an antigenic site from foot-and-mouth disease virus (Usha et al., Virology 197, 366-374, 1993). Analysis of progeny RNA produced during such an infection has revealed that the inserted sequence is rapidly lost during serial passaging, probably by a process of homologous recombination. Using the information gained from this analysis, we have redesigned the chimeras in such a way that they are now genetically stable. The modified constructs have been used to obtain large quantities of purified virus particles expressing epitopes derived from human rhinovirus 14 (HRV-14) and human immunodeficiency virus type 1 (HIV-1). The chimeric virus particles possess the antigenic properties of the inserted sequence and, in the case of the HRV-14-derived construct, it has been shown that the inserted epitope is immunogenic in rabbits. These results demonstrate that CPMV can be used as a high-yielding system for the presentation of foreign peptide sequences.

The endothelins are a family of three 21-amino-acid peptides: endothelin-1, endothelin-2 and endothelin-3. They are powerfully vasoactive, causing both contraction and relaxation of blood vessels. They are also active in the lung causing long lasting bronchoconstriction. Antibodies were raised in rabbits against the C-terminal heptapeptide of endothelin-1 (endothelin-1(15-21)) and to portions of the C-terminus of the human proendothelin-1(31-38), proendothelin-2(31-37) and proendothelin-3(31-41 amide) and tested by enzyme-linked immunosorbent assay to determine their titre and cross-reactivity. We used these antibodies to determine the localization of mature endothelin in the adult human lung and to determine the distribution of each of the three proendothelins. Mature endothelin immunoreactivity was present in airway epithelia and submucosal glands throughout the lung. In the airway epithelia immunoreactive proendothelin-1 and proendothelin-3 were detected, while immunoreactivity of all three isoforms was present in submucosal glands. Quantitative in vitro receptor autoradiography was used to locate specific endothelin binding sites. The rank order for density of endothelin binding site occurrence was: lung parenchyma greater than airway smooth muscle greater than airway epithelia. If immunoreactive endothelin is released onto these sites in vivo, endothelin may act as a paracrine mediator in the human lung.

Comparison of protein kinase activity in normal and regenerating rat liver nuclei indicates that exogenous histone H1 is hyperphosphorylated in 22-h regenerating nuclei. The protein kinase involved is not sensitive to protein kinase A inhibitor, is inhibited by staurosporine and by an anti-PKC polyclonal antibody, utilizes only ATP, and also phosphorylates the C-terminal fragment of histone H1. These data suggest that protein kinase C is responsible for the observed effects, in agreement with the presence of this enzyme in normal and regenerating nuclei demonstrated by immunoblotting.

To investigate the mode of gene expression of red clover mottle virus (RCMV) middle component (M) RNA, we have synthesized an oligopeptide corresponding to the predicted carboxy-terminus of the RCMV counterparts of the cowpea mosaic virus (CPMV) 48K and 58K proteins. Using an antiserum raised against this synthetic oligopeptide, we have detected a 43-kDa protein in the 30,000 g pellet from extracts of RCMV-infected cowpea protoplasts. Immunogold cytochemistry further localized this protein to the plasmodesmata of RCMV-infected pea tissue. This subcellular location, taken together with other evidence, suggests that this 43-kDa protein has a role in the cell-to-cell spread of RCMV.