Construction of a Novel DNA Vaccine Candidate Encoding an HspX-PPE۴۴-EsxV Fusion Antigen of Mycobacterium tuberculosis

Background: Mycobacterium tuberculosis is the causative agent of tuberculosis (TB). Bacille Calmette-Guerin (BCG) vaccine, is not effective in adults, therefore, many efforts have been made to produce an effective adult TB vaccine. The aim of this study was to develop a new tuberculosis DNA vaccine candidate encoding a recombinant HspX-PPE۴۴-EsxV fusion antigen of M. tuberculosis. Methods: A fusion DNA segment consisting of HspX, linker, PPE۴۴, linker, and EsxV, after codon optimization, was designed. The fusion DNA was cloned and its sequence confirmed. Then, expression of a recombinant pcDNA۳.۱ (+)/HspX-PPE۴۴-EsxV plasmid in Chinese hamster ovary (CHO) cells was verified by RT-PCR and Western-blot analysis. Results: A ۱۹۶۸ bp band in RT-PCR and a ۶۸ kDa band on Western-blot analysis confirmed transcription and expression of recombinant hspX-ppe۴۴-esxV in eukaryotic cells. Conclusions: A recombinant DNA segment encoding the HspX-PPE۴۴-EsxV fusion antigen of M. tuberculosis was constructed and considered to be tested as a new TB DNA vaccine candidate.