Summary auto-generated
This paper describes the construction of a cassette vector based on the Sabin 1 poliovirus vaccine strain that enables rapid insertion of foreign amino acid sequences into antigenic site 1, a neutralizing epitope located on capsid protein VP1. The researchers engineered unique restriction sites (SalI and DraI) flanking antigenic site 1 in a full-length infectious cDNA clone using oligonucleotide-directed mutagenesis. This design allows direct replacement of the site 1 region with synthetic oligonucleotides without requiring additional subcloning steps. The vector was tested by inserting antigenic sequences from hepatitis A virus, human rhinovirus serotypes 2 and 14, and coxsackievirus B4. Most chimeric viruses remained viable and retained recognition of the poliovirus receptor, though growth characteristics varied. All chimeras were neutralized by poliovirus type 1 antisera and monoclonal antibodies against sites 2 and 3, but not site 1, indicating successful antigenic modification. The results demonstrate that antigenic site 1 is highly flexible and can accommodate diverse foreign sequences while maintaining viral viability, making the Sabin 1 vaccine strain a promising vehicle for presenting epitopes from other pathogens in vaccine development.
Key findings
- A cassette vector with unique restriction sites flanking antigenic site 1 of Sabin 1 poliovirus was successfully engineered, enabling single-step insertion of foreign amino acid sequences without subcloning.
- Antigenic site 1 exhibits high flexibility and can accommodate amino acid sequences from hepatitis A virus, rhinovirus, and coxsackievirus while maintaining virus viability.
- Chimeric viruses containing foreign antigenic sequences were not recognized by monoclonal antibodies against site 1 but remained sensitive to poliovirus type 1 polyclonal antiserum and antibodies against sites 2 and 3.
- All tested chimeras retained the ability to recognize and utilize the poliovirus cellular receptor, indicating that antigenic modifications did not alter receptor specificity.
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Abstract
A cassette vector has been constructed which allows the rapid and extensive modification of one of the neutralizing antigenic sites of the Sabin 1 poliovirus vaccine strain, P1/LSc 2ab. Unique restriction endonuclease sites flanking antigenic site 1 have been engineered into a full-length infectious Sabin 1 cDNA clone with minimal alteration to the coding sequence. This facilitates replacement of this region by oligonucleotides encoding foreign amino acid sequences. Our results indicate that this region is highly flexible in terms of the number and sequence of amino acids which can be accommodated.