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Expression of streptococcal M protein in mammalian cells
D E Hruby1, W M Hodges, E M Wilson
1Department of Microbiology, Oregon State University, Corvallis 97331.
Abstract:
The M protein encoded by group A streptococci is a cell-wall polypeptide that has the property of enabling these organisms to evade the phagocytic cells of the human host. Therefore, the M protein plays a major role in the pathogenesis of streptococcal diseases. As an initial step toward the use of this protein as a target antigen for the production of protective anti-streptococcal immunity, a live vaccinia virus recombinant containing the M-protein gene has been constructed (VV:M6 delta). The bacterial M-protein DNA sequence is stable within this genetic context and is actively transcribed by viral RNA polymerase. Furthermore, high levels of immunoreactive M protein were detected in vivo when the VV:M6 delta recombinant was used to infect mammalian cells in culture. Thus, in addition to providing a powerful approach for dissecting the immunodominant domains of the M protein, the VV:M6 delta recombinant appears to be an excellent candidate vaccine for animal trials.
Insights
Group A Streptococcus M protein aids bacterial evasion. A vaccinia virus recombinant (VV:M6 delta) expressing M protein shows promise as a vaccine candidate for preventing streptococcal diseases.
Area of Science:
- Microbiology
- Immunology
- Vaccinology
Background:
- Group A Streptococcus (GAS) causes various diseases.
- The GAS M protein is crucial for immune evasion and pathogenesis.
- Developing effective vaccines against GAS is a public health priority.
Purpose of the Study:
- To construct a recombinant vaccinia virus expressing the M protein gene.
- To assess the stability and expression of the M protein gene in the viral vector.
- To evaluate the potential of this recombinant as a vaccine candidate.
Main Methods:
- Gene construction: M protein gene inserted into vaccinia virus.
- Stability assessment: Bacterial DNA sequence stability within the viral genome.
- Expression analysis: Detection of M protein in infected mammalian cells.
Main Results:
- The M protein DNA sequence was stable in the vaccinia virus recombinant (VV:M6 delta).
- The M protein gene was actively transcribed by viral RNA polymerase.
- Immunoreactive M protein was detected in vivo in infected cells.
Conclusions:
- The VV:M6 delta recombinant provides a tool for studying M protein immunodominant domains.
- This recombinant shows potential as a vaccine candidate for animal trials.
- Further research may lead to novel strategies for combating streptococcal infections.