Porcine reproductive and respiratory syndrome virus (PRRSV) is a pathogen that severely disrupts swine production. Despite sustained efforts, the disease is still endemic, with high mortality and morbidity. New antiviral strategies to control PRRSV are needed. Griffithsin, a red algal lectin, has potent antiviral effect on several human enveloped viruses, but this effect has not been demonstrated on PRRSV. Here, we first tested the in vitro antiviral activity of Griffithsin against PRRSV. Griffithsin exerted strong saccharide-dependent antiviral activity against PRRSV, probably through interactions with glycans on the surface of PRRSV that interfered with virus entry. Furthermore we revealed Griffithsin’s action on PRRSV involved blocking viral adsorption, and it had no effect on viral penetration. Besides our findings suggested Griffithsin may interferes with cell-to-cell spread to prevent virus transmission. The remarkable potency profile of Griffithsin supports its development as an antiviral agent against PRRSV.

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Fig. 1. Identification of recombinant plasmid pUC57-Griffithsin and SDS-PAGE analyses of Griffithsin. (A) Recombinant plasmid pUC57-Griffithsin was digested by NdeI–XhoI and verified in 1% Agarose Gel. (B) Recombinant Griffithsin was purified by Ni2+- Sepharose HisTrap HPTM affinity column by the analysis of Crude extract (Crude), Flow-through after loading crude extract on affinity column (FT), Fraction obtained by washing with 50 mM imidazole (Wash) and Fractions eluted with 300 mM imidazole.

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