M. N. Zhmak

A peptide construct containing B-cell and T-cell epitopes from the foot-and-mouth disease viral VP1 protein induces efficient antiviral protection

A new peptide construct Palm135-158-GGA-170-188(Acm) has been synthesized and investigated in a number of in vitro and in vivo test systems. The construct contains a virus specific T-helper epitope within the 170-188 sequence of VP1, in addition to the main antigenic 135-158 region of the foot-and-mouth disease viral VP1 protein (strain A22). The construct has higher protective, antigenic, immunogenic and T-cell proliferative activity then the previously described shorter peptide Palm(2)135-159. The 170-188 part of the construct serves as a virus specific T-epitope, responsible for the enhanced immunogenic and protective activity of the construct.

Synthetic vaccine against foot-and-mouth disease based on a palmitoyl derivative of the VP1 protein 135–159 fragment of the A22 virus strain

The peptide Palm2 135-159, a dipalmitoyl derivative of the 135-159 fragment of VP1 protein of the foot-and-mouth disease virus strain A22 was synthesized. In the experiments on mice, guinea pigs and sheep Palm2 135-159 possesses greater immunogenic and protective activity than the nonacylated 135-159 peptide. The synthetic vaccine against foot-and-mouth disease for use in sheep was developed on the basis of the lipopeptide. Synthetic polymethylsiloxane oil was found to be a suitable adjuvant for this vaccine. The dependencies of protective and immunogenic effects from the dose of peptide were studied. The vaccine was found to be stable to storage for 1 year at 18 degrees C. It was shown that the synthetic vaccine provides 1 year protection of sheep against foot-and-mouth disease after a single administration. The vaccine is allowed for veterinary use in Russia.

Synthetic Peptide Constructs on the Basis of Immunoactive Fragments of the A22 Strain VP1 of the Foot-and-Mouth Disease Virus

Abstracts—Peptide constructs consisting of 44–53 aa were synthesized on the basis of sequences 135–159, 170–190 and 197–213 of VP1 from the foot-and-mouse disease A22 strain. Immunogenic and protective properties of the peptide constructs were studied in guinea pigs and mice of three lines. The constructs were shown to induce higher levels of antibodies and exhibit higher protective effects than the separate peptides. The most active among the peptides studied was the construct involving the VP1 fragments 135–160 and 170–190: it protected pigs from the experimental infection by the foot-and-mouth disease virus.

Effect of a peptide modeling the nicotinic receptor binding site on the spectral and luminescent properties of dye complexes with cucurbit[8]uril

The paper presents the results of analysis of the effect of a high-affinity peptide (HAP) homologous to a fragment of the nicotinic acetylcholine receptor (nAChR) on the absorption and fluorescence spectra of thiazole orange and thioflavin T complexes with cucurbit[8]uril in aqueous solution. In the presence of HAP, a change in the absorption spectra of the dye complexes and a drop in the fluorescence intensity occur; for thiazole orange, the fluorescence intensity is restored to the initial level in the presence of α-bungarotoxin capable of high-affinity binding to nAChR. The proposed method make it possible to detect the presence of α-bungarotoxin.

Structure prediction for peptides capable of inducing antibody formation in mice

A simple method for the sequence prediction of peptides capable of thein vivo stimulation of antibody production in mice without conjugation with protein carriers was proposed on the basis of literature data on the structure of T-helper epitopes active in vivo. According to this approach, a potentially active peptide should contain a nine-membered sequence with a hydrophobic amino acid residue in the first position and a positively charged residue in the ninth position. The efficiency of this approach was confirmed by the presence of such sequences in the previously described synthetic peptides with immune activities, by the application of this approach to the choice of immunogenic fragments within the sequences of various proteins that exhibited further the specific activity, and by the construction of immunogenic peptides on the basis of inactive natural sequences.

The effect of MII α-conotoxin and its N-terminal derivatives on Ca2+- and Na+-signals induced by nicotine in SH-SY5Y neuroblastoma cells

Nicotinic acetylcholine receptors (nAChRs) are involved in the regulation of intracellular Ca2+-dependent processes both in normal and pathological states. α-Conotoxins from the venom of Conus marine mollusks are a valuable tool for the investigation of the pharmacological action and functional role of nAChRs. Analogues of α-conotoxin MII labeled by Bolton-Hunter reagent (BH-MII) or fluorescein isothiocyanate (FITC-MII) on the N-terminal glycine residue have been synthesized in the present work. Fluorescence microscopy studies of SH-SY5Y neuroblastoma cells loaded with Ca2+ indicator Fura-2, or by both Ca2+ indicator Fluo-4 and Na+ indicator SBFI, were used to test the effect of MII modification on its ability to block Ca2+ and Na+ signals induced by nicotine. Measurements in SH-SY5Y cells showed that kinetics of the increase and recovery of the concentration of free Ca2+ ([Ca2+]i) upon nicotine application and washout was different from that for free Na+ ([Na+]i), this being evidence of differences in the mechanism of Ca2+ and Na+ homeostasis regulation. MII suppressed the nicotine-induced increase of [Ca2+]i and [Na+]i in a concentration-dependent manner. An additional tyrosine residue added to the N-terminus of one of the MII derivatives caused a significant decrease in the inhibitory action of MII; this decrease was even more pronounced when a large FITC label was introduced into MII. The BH-MII derivative had an inhibitory effect similar to that of unmodified α-conotoxin. MII and its iodinated derivatives are promising tools for radioligand assays.

Production of antibodies to the α7-subunit of human acetylcholine receptor with the use of immunoactive synthetic peptides

Potential B epitopes and T-helper epitopes in the N-terminal extracellular domain of the α7-subunit of human acetylchloline receptor (AChR) were theoretically calculated in order to reveal peptides that can induce the formation of specific antibodies to this domain. Four peptides structurally corresponding to four α7-subunit regions containing 16–23 aa and three of their truncated analogues were synthesized. Rabbits were immunized with both free peptides and protein conjugates of their truncated analogues, and a panel of antibodies to various exposed regions of the N-terminal extracellular domain of the AChR α7-subunit was obtained. All of the four predicted peptides were shown to induce the production of antipeptide antibodies in free form, without conjugation with any protein carrier. The free peptides and the protein conjugates of truncated analogues induced the formation of almost equal levels of antibodies. Most of the obtained antisera contained antibodies that bind to the recombinant extracellular N-terminal domain of the rat AChR α7-subunit and do not react with the analogous domain of the α1-subunit of the ray Torpedo californica AChR.

Induction of Immune Response by Synthetic Fragments of the Bovine Prion Protein and Their Analogues in Mice of Various Lines

Antibodies to the bovine prion protein were produced by immunizing mice of three lines with five synthetic fragments of the protein and six of their analogues. The analogues contained amino acid substitutions that, according to theoretical calculation, should lead to an increase in the immunogenic activity of peptides. All the peptides except for one induced the formation of antibodies. All the sera containing the antipeptide antibodies were tested by an immunohistochemical method. The sera effectively bound to brain preparations from an animal with spongiform encephalopathy were identified; it was shown that they do not interact with preparations of normal brain. Therefore, it was shown that the immunization of mice with synthetic fragments of a prion protein allows one to obtain specific antibodies suitable for the study and diagnostics of prion diseases.

Photoactivatable Analogues of α-Conotoxins GI and MI and Their Interaction with Nicotinic Acetylcholine Receptor

Two photoactivatable analogues of α-conotoxin GI with the benzoylphenylalanine residue (Bpa) substituted for His10 or Tyr11 were synthesized using the method of solid-phase peptide synthesis. In addition, α-conotoxin MI was chemically modified by placing an azidobenzoyl or a benzoylbenzoyl photo label at Nα of Gly1 or Nε of Lys10. All the photoactivatable analogues were purified by HPLC, their structures were confirmed by MALDI MS, and the label positions in their molecules were localized by MS of their trypsinolysis fragments. All the analogues interacted with the nicotinic acetylcholine receptor (AChR) from Torpedo californica as efficiently as the native α-conotoxins, with the differences in the inhibition constants being within one order of magnitude under the same conditions. [125I] Derivatives prepared from all the analogues retained the ability to be bound by AChR and were used in the photoinduced AChR crosslinking. All the AChR subunits were found to be crosslinked to the photoactivatable analogues, with the linking depending on both the chemical nature of label and its position in the α-conotoxin molecule.