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Biomedical subjects

R A Lerner

Publications and source records attributed to R A Lerner.

At least 163 records · Page 9Linked to original sources
PubMed1983

Synthetic vaccines.

Synthetic vaccines are designed with the help of computer-graphics programs. These displays generated by Arthur J. Olson of the Research Institute of Scripps Clinic show a method whereby parts of a viral protein that are on the surface of a virus, and therefore accessible to antibodies, can be identified. The backbone of the surface domain of the protein on the outer shell of the tomato bushy-stunt virus is displayed (1) on the basis of coordinates determined by Stephen C. Harrison of Harvard University and his colleagues. A single peptide of the protein is picked out in yellow, with the side chains of its component amino acids indicated in atomic detail (2). The peptide is enlarged and a sphere representing a water molecule is displayed (3). The sphere is rolled around the peptide to generate a map of the surface accessible to water (4); it does so, following an algorithm developed by Michael L. Connolly, by placing a dot at each point of its closest contact with the peptide, taking account of the sphere's own van der Waals radius (zone of influence, in effect) and that of each atom of the peptide and the rest of the protein. A similar-dot-surface map is generated to show what parts of the peptide are still accessible to water when three copies of the protein are associated in an array on the surface of the virus (5) and when four such arrays (out of 60) are in position on the outer surface of the virus (6).

Animals↗
PubMed1983

Generation of protein-reactive antibodies by short peptides is an event of high frequency: implications for the structural basis of immune recognition.

Recent studies have shown that chemically synthesized small peptides can induce antibodies that often react with intact proteins regardless of their position in the folded molecule. These findings are difficult to explain in view of the experimental and theoretical data which suggest that in the absence of forces provided by the folded protein, small peptides in aqueous solution do not readily adopt stable structures. In order to rationalize the two findings, there has been general acceptance of a stochastic model which suggests that the multiple conformers of a peptide in solution induce sets of antibodies with a small percentage reactive with conformations shared by the folded protein. This stochastic model has become less tenable as the success rate for the generation of protein-reactive anti-peptide antibodies has grown. To test the stochastic model, we have used monoclonal anti-peptide antibodies as a way of estimating the frequency with which small peptides induce antibodies that react with folded proteins. We have made monoclonal antibodies to six chemically synthesized peptides from three proteins. The frequency with which the peptides induce protein-reactive antibodies is at least 4 orders of magnitude greater than expected from previous experimental work and vastly different from what would be predicted by calculating the possible number of peptide conformers in solution. These findings make the stochastic model less likely and lead to consideration of other models. Aside from their practical significance for generation of highly specific reagents, these findings may have important implications for the protein folding problem.

Amino Acid Sequence↗
PubMed1983

Chemically synthesized peptides of hepatitis B surface antigen duplicate the d/y specificities and induce subtype-specific antibodies in chimpanzees.

Synthetic peptides, predicted from the nucleotide sequence of the S gene of hepatitis B virus were analyzed in terms of the established specificities of the hepatitis B surface antigen. The analysis indicated that the group-specific alpha antigen is composed of at least three nonoverlapping sequences and that a relatively hydrophilic region of the surface antigen protein, spanning amino acid residues 110-137, specifies the major d and y subtype system. The d/y subtype appears to depend on changes in one or more variable amino acids at positions 127, 131, and 134 of the hepatitis B surface antigen protein. Peptide 49 (consisting of amino acid sequences of the y subtype for the region 110-137), coupled to a carrier protein and mixed with an adjuvant, stimulated a brisk anti-y response in chimpanzees, the relevant model of human response to hepatitis B virus immunization and infection. Experimental challenge with homologous hepatitis B virus resulted in a pattern of partial protection. The results offer promise for the application of chemically synthesized peptides as vaccines in the prophylaxis of hepatitis B virus disease.

Amino Acid Sequence↗
PubMed1983

Synthetic peptide immunogens as vaccines.

Synthetic peptide immunogens have been shown to elicit antibodies that can react with full-length proteins containing that peptide. Such antibodies are directed against a specific region of the protein chosen in advance by the investigator and so have a predetermined specificity. In basic research, these antibodies are useful in identifying the protein product of an open reading frame, localizing the gene product to particular cells or subcellular organelles, identifying the enzymatic function of a protein product, following the fate of particular regions of a product through protein maturation processes, analyzing the expression of exons following DNA rearrangements and RNA splicing, and purifying the protein by immunoaffinity chromatography techniques. In medicine, such antibodies may provide reagents for passive vaccination, antitoxin therapy, and targeted immunotherapy of neoplasia. The peptides themselves may be used as synthetic vaccines. The immediate future of the synthetic peptide immunogen in medicine is clear--the promise demonstrated in the laboratory must be reduced to safe application in the hospital. Two barriers to this are the selection of precisely the best peptide and the selection of the proper adjuvant. Currently, a brute force approach is utilized to find the best peptide for eliciting the desired antibodies. This is clearly a problem when the pathogenic organism is assayable only in man. Possibly, by combining studies on the antigenicity of the pathogenic organism with an analysis of naturally occurring variants that alter its immunogenicity, peptide selection will be made easier. Also, since the adjuvants and carriers used in the laboratory are in general too harsh for widespread use in humans and animals, much work needs to be done to find suitable adjuvants and carriers. Nonetheless, now that the major conceptual hurdle to synthetic peptide vaccines has been cleared (that is, it is not necessary to reproduce conformation exactly), it should be relatively straightforward to solve the remaining problems.

Animals↗
PubMed1982

Tapping the immunological repertoire to produce antibodies of predetermined specificity.

We understand the structure of antibodies in detail, but know little about the molecular basis of the immunogenicity of proteins. Recent experiments have shown that chemically synthesized peptides representative of virtually any part of the surface of a protein can elicit antibodies reactive with the native molecule. Such peptides can serve as synthetic vaccines, and antibodies, useful in the study of changes in protein structure, can be generated. As these antibodies react with regions of the protein known in advance to the experimenter, they can be said to be of predetermined specificity.

Antibody Specificity↗
PubMed1982

Immunogenic structure of the influenza virus hemagglutinin.

We chemically synthesized 20 peptides corresponding to 75% of the HA1 molecule of the influenza virus. Antibodies to the majority (18) of these peptides were capable of reacting with the hemagglutinin molecule. These 18 peptides are not confined to the known antigenic determinants of the hemagglutinin molecule, but rather are scattered throughout its three-dimensional structure. In contrast, antibody raised to intact hemagglutinin did not react with any of the 20 peptides. Taken together these results suggest that the immunogenicity of an intact protein molecule is not the sum of the immunogenicity of its pieces.

Amino Acid Sequence↗
PubMed1982

A biologically active receptor for the carbohydrate-binding protein(s) of Dictyostelium discoideum.

Recent biochemical and genetic evidence has shown that carbohydrate-binding protein (CBP-26) is intimately involved in the cell-cell cohesion process. We have isolated a cell-surface-associated receptor molecule for CBP-26 by affinity chromatography. The receptor has a molecular weight of 80,000 daltons. The CBP receptor is constitutively expressed during development. Most significantly, the receptor, when added to aggregation-competent cells, blocks the cells' ability to reaggregate. These results suggest that CBP and its receptor play an important role in the cell cohesion and aggregation process.

Cell Aggregation↗
PubMed1982

Common 82-nucleotide sequence unique to brain RNA.

Several randomly selected cDNA clones made from rat brain polyA+RNA have unusual properties. Although the cDNA inserts are 500-1,250 base pairs long, they hybridize to a 160-nucleotide RNA species that is present in brain but not in liver or kidney. Nucleotide sequence studies of two of the clones and hybridization studies show that a common 82-nucleotide sequence is responsible for the hybridization. The same sequence is located in the second intron of a rat growth hormone gene. These studies suggest that signals called "ID sequences" may be carried in the introns of genes and prescribe their tissue-specific expression.

Base Sequence↗
PubMed1982

A genetic locus regulates the expression of tissue-specific mRNAs from multiple transcription units.

129 GIX- mice, unlike animals of the congeneic partner strain GIX+, do not express significant amounts of the retroviral antigens gp70 and p30. Evidence is presented indicating that the GIX phenotype is specified by a distinct regulatory gene acting on multiple transcription units to control the levels of accumulation of specific mRNA species. The steady-state levels of retroviral-homologous mRNA from the tissues of GIX+ and GIX- mice were examined by blot hybridization using as probes DNA fragments from cloned murine leukemia viruses. RNA potentially encoding viral antigens was reduced or absent in GIX- mice, even though no differences in integrated viral genomes were detected between these congeneic strains by DNA blotting. Tissue-specific patterns of accumulation of these RNA species were detected in brain, epididymis, liver, spleen, and thymus, and several distinct RNA species were found to be coordinately regulated with the GIX phenotype. Measurements of RNA synthesis suggest a major role for transcriptional control in the regulation of some retroviral messages.

Animals↗
PubMed1981

Sequence-specific antibodies show that maturation of Moloney leukemia virus envelope polyprotein involves removal of a COOH-terminal peptide.

We followed maturation of the glycosylated envelope polyprotein Pr80env of a murine retrovirus by using antisera specific to subregions of the protein, including an antiserum directed against a synthetic peptide corresponding to the COOH-terminus of Pr80env. Shortly after synthesis and glycosylation, Pr80env is cleaved into two species, gp70 and Pr15E, that are found associated, perhaps through disulfide bonds, in infected cells. Pr15E is further cleaved at the time of virus maturation to form virus protein p15E. NH2-Terminal protein sequence analysis showed that Pr15E had an NH2 terminus in common with p15E. Pr15E, but not p15E, is precipitated by antibody against the COOH-terminal peptide; hence, p15E is missing a peptide at the COOH-terminus. Our data indicate that Pr15E is the predominant species in cells and p15E is the major species in virus.

Amino Acid Sequence↗
PubMed1981

Chemically synthesized peptides predicted from the nucleotide sequence of the hepatitis B virus genome elicit antibodies reactive with the native envelope protein of Dane particles.

Thirteen peptides corresponding to amino acid sequences predicted from the nucleotide sequence of the hepatitis B surface antigen were synthesized chemically. The free or carrier-linked synthetic peptides were injected into rabbits, and 7 of the 13 elicited an antipeptide response. Antisera against four of the six soluble peptides longer than 10 amino acids were reactive with native antigen and specifically precipitated the 23,000- and 28,000-dalton forms from Dane particles. As the hepatitis molecule had not been chosen for study because of any structural feature suggesting unique opportunities for success, these results suggest that the strategy is general and should work for any protein as long as enough domains are studied. Peptides such as these could prove to be ideal vaccines.

Amino Acid Sequence↗