Evaluation of immunoprotective effect of NFA47650 protein from Nocardia farcinica

  Objective  To access the capacity of NFA47650 protein from Nocardia farcinica in activating innate immune response and evaluate its immunoprotective effect.

  Methods  The sequence characteristics of nfa47650 were analyzed by bioinformatics, and its conservation in N. farcinica was analyzed by Blast. RAW264.7 cells were stimulated with purified NFA47650 protein, the level of MAPK signaling pathway activation was detected by Western Blot, and the concentration of cytokines in the supernatant were measured by ELISA. C57BL/6 mice were divided into two groups to be immunized with PBS or NFA47650 protein for three times, respectively. After serum titer was detected, the changes of body temperature, body weight, serum IgG level, protein and LDH level in alveolar lavage fluid, pulmonary bacterial loads and cytokine levels were detected at 24 hours after infection.

  Results  NFA47650 protein can stimulate RAW264.7 cells to upregulate the phosphorylation levels of ERK, JNK, P38 and induces the production of various cytokines such as IL-10, IL-12, TNF-α, IFN-γ. In addition, immunized mice produced high-titer antisera, resulting in less damage and bacterial loads in lung tissues.

  Conclusion  NFA47650 protein is an immunodominant protein with immunoprotective effects that stimulates the host to produce antibodies and induces an immune response in mice during N. farcinica infection.