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Location and characterization of the antigenic portion of the FMDV immunizing protein
Abstract:
Purified foot-and-mouth disease virus (FMDV) to type O1K was treated with several endopeptidases of differing specificity. The immunizing protein VPThr was cleaved into two detectable fragments by all enzymes except for glutamic acid-specific Staphylococcus aureus V8 protease. The longest fragments were generated by mouse submaxillary gland protease and the shortest by trypsin treatment of the intact virion. Several fragments, including the peptides resulting from the cyanogen bromide (CNBr) cleavage of the isolated protein VPThr were characterized in terms of their molecular weights N- and C-terminal amino acids, and ability to induce virus-specific antibodies. The order of the fragments along the protein was determined, and then located on the amino acid sequence of the protein. Two enzyme-sensitive areas of the protein were found on the surface of the virion: between sequence positions 138 and 154 and between portion 200 and the C terminus. Peptides containing these sections were able to induce neutralizing antibodies against the homologous FMDV. When the virus was treated with trypsin or with chymotrypsin, several amino acids between the detectable fragments were lost and the infectivity of the virus was reduced. The infectivity was retained, however, when the enzyme treatment resulted in cleavage of protein with no loss of amino acids or only the cutting away of the C-terminal section. These results suggest that the property of cell attachment is restricted to small regions of the surface of the virus particle.
Insights
Foot-and-mouth disease virus (FMDV) structural protein VPThr was cleaved by proteases to identify antibody-inducing regions. Enzyme-sensitive sites on the FMDV surface were mapped, revealing key areas for cell attachment and antibody generation.
Area of Science:
- Virology
- Structural Biology
- Immunology
Background:
- Foot-and-mouth disease virus (FMDV) is a significant pathogen affecting livestock.
- Understanding the structural proteins of FMDV is crucial for vaccine development and antiviral strategies.
- The VPThr protein is a key immunogenic component of the FMDV virion.
Purpose of the Study:
- To map enzyme-sensitive regions on the FMDV VPThr protein.
- To determine the relationship between protein cleavage, viral infectivity, and antibody induction.
- To identify regions of the FMDV surface responsible for cell attachment.
Main Methods:
- Purified FMDV (type O1K) was treated with various endopeptidases.
- Cleavage fragments of VPThr were analyzed for molecular weight, N- and C-terminal amino acids.
- Peptides were characterized by their ability to induce virus-specific antibodies.
- Cyanogen bromide (CNBr) cleavage was used to further analyze VPThr fragments.
- Viral infectivity was assessed after enzyme treatment.
Main Results:
- VPThr was cleaved by most proteases, except Staphylococcus aureus V8 protease.
- The longest and shortest fragments were generated by mouse submaxillary gland protease and trypsin, respectively.
- Two enzyme-sensitive regions on the virion surface were identified: positions 138-154 and 200-C terminus.
- Peptides from these regions induced neutralizing antibodies against FMDV.
- Viral infectivity was reduced when amino acids were lost during cleavage but retained if cleavage was precise or removed only the C-terminus.
Conclusions:
- Specific regions on the FMDV VPThr protein surface are critical for inducing neutralizing antibodies.
- These identified regions are also implicated in the virus's cell attachment property.
- Precise enzymatic cleavage of FMDV VPThr can yield fragments capable of inducing protective immunity without compromising infectivity.
- This study provides insights into FMDV structure-function relationships relevant to antiviral interventions.