Spinacia oleracea proteins with antiviral activity against tobacco mosaic virus

Tobacco mosaic virus (TMV) is a devastating microorganism with a global distribution and a wide host range. Protein extracts isolated from Spinacia oleracea (spinach) were examined with bioassay-guide and tested for the resistance to TMV in the Nicotiana glutinosa leaves by local lesion assay. The results show that the crude extract and the fraction of 0 to 40% ammonium sulfate precipitation could protect tobacco from TMV infection. An active fraction was further purified with cation-exchange chromatography (SP-sepharose HP) and activity screening. The inhibitory rate for TMV in vitro was up to 94.35% with 50 µg/mL of the active fraction. In addition, this active fraction could function against TMV at the infection sites on leaves of N. glutinosa . However, it had only a little inhibitory effect on TMV replication and the mechanism under the TMV-inhibitory activity of protein extract from spinach still need further investigation.