Production and characteristics of strain common antibodies against a synthetic polypeptide corresponding to the C-terminal region of potato virus Y coat protein

Development and characterization of antacid microcapsules to buffer the acidic intervertebral disc microenvironment

During intervertebral disc (IVD) degeneration, microenvironmental challenges such as decreasing levels of glucose, oxygen, and pH play crucial roles in cell survival and matrix turnover. Antacids, such as Mg(OH)2 and CaCO3, entrapped in microcapsules are capable of neutralizing acidic microenvironments in a controlled fashion and therefore may offer the potential to improve the acidic niche of the degenerated IVD and enhance cell-based regeneration strategies. The objectives of this work were, first, to develop and characterize antacid microcapsules and assess their neutralization capacity in an acidic microenvironment and, second, to combine antacid microcapsules with cellular microcapsules in a hybrid gel system to investigate their neutralization effect as a potential therapeutic in a disc explant model. To achieve this, we screened five different pH- neutralizing agents (Al(OH)3, Mg(OH)2, CaCO3, and HEPES) in terms of their pH neutralization capacities, with Mg(OH)2 or CaCO3 being carried forward for further investigation. Antacid-alginate microcapsules were formed at different concentrations using the electrohydrodynamic spraying process and assessed in terms of size, buffering kinetics, cell compatibility, and cytotoxicity. Finally, the combination of cellular microcapsules and antacid capsules was examined in a bovine disc explant model under physiological degenerative conditions. Overall, CaCO3 was found to be superior in terms of neutralization capacities, release kinetics, and cellular response. Specifically, CaCO3 elevated the acidic pH to neutral levels and is estimated to be maintained for several weeks based on Ca2+ release. Using a disc explant model, it was demonstrated that CaCO3 microcapsules were capable of increasing the local pH within the core of a hybrid cellular gel system. This work highlights the potential of antacid microcapsules to positively alter the challenging acidic microenvironment conditions typically observed in degenerative disc disease, which may be used in conjunction with cell therapies to augment regeneration.

Analysis of potato virus Y coat protein epitopes recognized by three commercial monoclonal antibodies

BACKGROUND

Potato virus Y (PVY, genus Potyvirus) causes substantial economic losses in solanaceous plants. Routine screening for PVY is an essential part of seed potato certification, and serological assays are often used. The commercial, commonly used monoclonal antibodies, MAb1128, MAb1129, and MAb1130, recognize the viral coat protein (CP) of PVY and distinguish PVYN strains from PVYO and PVYC strains, or detect all PVY strains, respectively. However, the minimal epitopes recognized by these antibodies have not been identified.

METHODOLOGY/PRINCIPAL FINDINGS

SPOT peptide array was used to map the epitopes in CP recognized by MAb1128, MAb1129, and MAb1130. Then alanine replacement as well as N- and C-terminal deletion analysis of the identified peptide epitopes was done to determine critical amino acids for antibody recognition and the respective minimal epitopes. The epitopes of all antibodies were located within the 30 N-terminal-most residues. The minimal epitope of MAb1128 was 25NLNKEK30. Replacement of 25N or 27N with alanine weakened the recognition by MAb1128, and replacement of 26L, 29E, or 30K nearly precluded recognition. The minimal epitope for MAb1129 was 16RPEQGSIQSNP26 and the most critical residues for recognition were 22I and 23Q. The epitope of MAb1130 was defined by residues 5IDAGGS10. Mutation of residue 6D abrogated and mutation of 9G strongly reduced recognition of the peptide by MAb1130. Amino acid sequence alignment demonstrated that these epitopes are relatively conserved among PVY strains. Finally, recombinant CPs were produced to demonstrate that mutations in the variable positions of the epitope regions can affect detection with the MAbs.

CONCLUSIONS/SIGNIFICANCE

The epitope data acquired can be compared with data on PVY CP-encoding sequences produced by laboratories worldwide and utilized to monitor how widely the new variants of PVY can be detected with current seed potato certification schemes or during the inspection of imported seed potatoes as conducted with these MAbs.

Production of strain specific antibodies against a synthetic polypeptide corresponding to the N-terminal region of the plum pox potyvirus coat protein

Comparison of the predicted coat protein amino acid sequence of the 'sweet cherry' strain of plum pox potyvirus (PPV-SwC) with the corresponding regions of several other PPV strains indicated that the main differences are in the N-terminal region. Polyclonal antibodies were produced against a synthetic peptide corresponding to the 1-14 sequence of the N-terminal region of PPV-SwC coat protein. They specifically detected PPV-SwC in different immunochemical tests.

Molecular characterization of coat protein genes of serologically distinct isolates of potato virus Y necrotic strain

The cost protein (CP) genes of two potato virus Y necrotic isolates (N27 and a mutant strain N27-92), which differed in their reactivity to a monoclonal antibody (mab), were characterized. Both isolates could be detected by mab 4E7, but mab VN295.5 selectively reacted to N27 and not to N27-92. The CP genes of both isolates coded for 267 amino acids with approximately 99.0% identity at both the nucleotide and the amino acid levels. nucleotide sequence comparison indicated five substitutions in N27-92 compared with N27. Three of these changes resulted in substitution of amino acids. Two transitions (A-->G) in N27-92 changed threonine to alanine and lysine to arginine at positions 7 and 55, respectively, whereas a A-->T transversion changed asparagine to isoleucine at positions 27. The surface probability curves of both the isolates could almost be superimposed, except at amino acid positions 7 and 27. Since amino acid substitution at position 55 is conservative, changes from polar to hydrophobic amino acids (threonine-->alanine and asparagine-->isoleucine) at positions 7 and 27 might have changed the epitope(s) of N27-92, abolishing its detection by mab VN295.5.