Recombinant porcine lung surfactant protein A inhibits porcine reproductive and respiratory syndrome virus infection into host cells in vitro

Abstract:

Abstract:［Objective］To investigate the antiviral activity of porcine lung surfactant protein A (SP-A) to porcine reproductive and respiratory syndrome virus (PRRSV) in vitro．［Methods］ The SP-A gene was amplified by PCR from the plasmid containing porcine SP-A gene，and subcloned into pcDNA3. 1A-CD5 vector containing the human CD5 signal peptide to generate SP-A eukaryotic expression vector pcDNA-CD5-SPA/MH．The recombinant expression vector was transfected into HEK293T cells mediated with calcium phosphate． The expressed recombinant SP-A was identified by Western blot and purified from culture medium by Ni-NTA-Agarose beads． The binding activity of SP-A with PRRSV was identified by ELISA． The antiviral activity of SP-A to PRRSV was analyzed by viral titer reduction assays on MARC-145 cells and porcine alveolar macrophages (PAM)．［Results］ The results showed that the eukaryotic expression vector of SP-A gene could mediate SP-A expression in HEK293T cells，the expressed SP-A could bind PRRSV in a dose dependent manner． The PRRSV incubated in advance with SP-A showed the lower infective activity compared with no-SP-Aincubated PRRSV on both MARC-145 cells and porcine alveolar macrophages． The SP-A-treated PRRSV titers in MARC-145 cells and PAM cells were significantly lower than that of SP-A-untreated PRRSV at 72 h post-infection．［Conclusion］ Recombinant porcine SP-A significantly inhibit the infection of PRRSV to the host cells in vitro，which indicates that recombinant SP-A possesses anti-PRRSV activity．