Research of Recombinant Influenza A Virus as a Vector for Mycoplasma Pneumoniae P1a and P30a

Methods: In this study, the major antigen genes P1a of MP adhesion factor P1(3862-4554 bases) and P30a of P30(49-822 bases) were inserted into the nonstructural protein (NS) gene of Influenza A virus strain A/Puerto Rio/8/34(H1N1), PR8 for short, to construct the recombinant vectors NS-P1a or NS-P30a. The recombinant pHW2000 plasmids containing NS-P1a or NS-P30a were co-transfected with the rest 7 fragments of PR8 into HEK293T cells. After inoculating chicken embryos, the recombinant influenza viruses rFLU-P1a and rFLU-P30a were rescued. RT-PCR and sequencing were used to identify the recombinant viruses. The hemagglutination titers of rFLU-P1a and rFLU-P30a were determined after 5 successive generations in chicken embryos so as to indicate the genetic stability of the recombinant viruses. The morphology of recombinant influenza viruses was observed under electron microscopy. Results: P1a or P30a was designed to be inserted into the modified NS gene sequence separately and synthesized successfully. RT-PCR identification of the recombinant viruses rFLU-P1a and rFLU-P30a showed that P1a (693bp), P30a (774bp), NS-P1a (1992bp) and NS-P30a (2073bp) bands were found, and the sequencing results were correct. After 5 successive generations, each virus generation has a certain hemagglutination titer(from 1:32 to 1:64), and the band of P1a or P30a can be seen in the corresponding positions. The virus particles under the electron microscope appeared as spheres or long strips connected by several particles, revealing a complete viral membrane structure composed of virus lipid bilayer, hemagglutinin, neuraminidase, and matrix proteins. Conclusion: The recombinant viruses rFLU-P1a and rFLU-P30a which carried the advantaged immune regions of the P1 and P30 genes in MP were successfully constructed and identified. The genetic stability of rFLU-P1a or rFLU-P30a was relatively high. The typical morphology of influenza virus was observed under the electron microscope. Our research provided a foundation for the further development of MP vaccines for human.