Summary auto-generated
This study evaluated a synthetic peptide (residues 397-420) from measles virus fusion protein as a potential vaccine candidate. The peptide was synthesized and characterized as linear despite containing two cysteine residues, with weak preference for α-helical structure. When used to immunize two mouse strains (BALB/c and C57BL/6), the peptide proved immunogenic, with antibodies recognizing the native virus in ELISA. However, the antibodies showed no neutralizing activity in vitro. Importantly, the peptide provided significant protection against intracerebral challenge with a neuroadapted measles virus strain when used for active immunization in C57BL/6 mice or passive antibody transfer in BALB/c mice. Fine specificity analysis using overlapping 8-mer peptides revealed strain-specific antibody recognition patterns, with BALB/c mice recognizing residues 407-417 and C57BL/6 mice recognizing 408-420. These findings suggest the 397-420 epitope warrants inclusion in future measles peptide-based vaccines, despite lacking neutralizing capacity in standard assays.
Key findings
- The 397-420 synthetic peptide from measles virus fusion protein was immunogenic in both BALB/c and C57BL/6 mouse strains, generating antibodies reactive with native virus
- Anti-peptide antibodies lacked neutralizing activity in vitro but provided significant protection against lethal neuroadapted measles virus challenge in mice via both active and passive immunization
- Fine specificity mapping revealed strain-dependent antibody recognition: BALB/c mice recognized residues 407-417 while C57BL/6 mice recognized residues 408-420 within the peptide
- The peptide existed as a linear structure despite two cysteine residues and showed weak α-helical propensity, suggesting potential in vivo cyclization may contribute to immune responses
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Abstract
A synthetic peptide representing residues 397-420 from the measles virus (MV) fusion (F) protein was tested for its structure, immunogenicity and protective capacity against intracerebral challenge with a neuroadapted strain of MV. Analysis of the peptide by mass spectrometry showed that it was linear, despite the presence of two cysteine residues in the sequence. Circular dichroism spectroscopy highlighted a weak preference for the peptide to adopt an alpha-helical conformation. The peptide was shown to be immunogenic in BALB/c and C57BL/6 mice after intraperitoneal immunization in Freund's adjuvant, and anti-peptide antibodies from both strains of mice reacted with the MV as a solid phase antigen on an ELISA plate. When the fine specificity of the anti-peptide antibody response was examined using overlapping 8-mer peptides, serum antibodies from BALB/c mice recognized the region between residues 407-417 whereas antibodies from C57BL/6 mice recognized the region 408-420 of the 397-420 peptide sequence. Although anti-397-420 antibodies had no demonstrable neutralizing activity, protection against challenge with a neuroadapted strain of MV was demonstrated following active immunization with peptide in C57BL/6 mice or after passive transfer of anti-peptide antibodies in BALB/c mice. These findings highlight the importance of the 397-420 region in the induction of protective antibodies in the MV encephalitis mouse model, and suggest that this epitope might be a good candidate for inclusion in a future MV synthetic peptide vaccine.