Agrocybe aegerita lection(Agrocybe aegerita antiviral protein,AAVP) is a novel fungal lectin. Half leaves assay showed that AAVP acquired activities of inhibition to tobacco mosaic virus infection on Nicotiana tobacum. The interaction of AAVP with coat protein of TMV was confirmed by IEF. AAVP showed no effect on three tested plant pathogeny fungi by testing filter paper wafer. AAVP showed activities of differentiation promotion of fruit body primordia from the mycelium of Agrocybe aegerita and Auricularia polytricha by being dripped on the surface of mycelium. Western blotting showed that the synthesis of AAVP occurred not only in fruiting bodies, but also in mycelia. The results suggested that there were several proteins in Hericium erinacous, Lentinula edodes, Volvariella volvacea, Pleurotus erygii and Ganoderma lucidum cross-reactivated with AAVP antiserum. The physiological function of AAVP found were antivirus and mycelium differentiation promotion activities. A large protein family with similar immunological properties to AAL may exist in most macrofungi playing various physiological roles in defense and mycelia differentiation in vivo.