Prevalence and ribavirin-mediated elimination of Morchella importuna endornavirus 1 (MiEV1) in cultivated Morchella species in China.

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Citation abstract

Fungal viruses compromise the cultivation of Morchella. We surveyed five mycoviruses (Morchella importuna endornavirus 1 [MiEV1], Morchella importuna endornavirus 2 [MiEV2], Morchella importuna endornavirus 3 [MiEV3], Morchella esculenta fusarivirus 1 [MeFV1], and Morchella esculenta fusarivirus 2 [MeFV2]) in 24 cultivated strains (8 M. importuna, 5 M. septimelata, and 11 M. sextelata) collected across 11 provinces in China and evaluated candidate antiviral agents. Only MiEV1 was detected, with a high incidence of 79.2 % (19/24) across all three Morchella species. Among seven tested chemicals (ampicillin, azithromycin, kanamycin, rifampicin, roxithromycin, acyclovir hydrochloride, and ribavirin), only ribavirin significantly inhibited MiEV1 replication. Successive ribavirin treatments eliminated MiEV1 from a representative M. sextelata strain (M11), with the virus-free status remaining stable after multiple subcultures on drug-free medium. Elimination of MiEV1 also significantly enhanced mycelial growth rate and biomass, and led to enhanced mycelial pigmentation, suggesting a potential negative impact of MiEV1 on vegetative growth and pigmentation in M. sextelata. These findings demonstrate that MiEV1 is prevalent in cultivated Morchella and that ribavirin provides an effective strategy for generating stable virus-free strains, offering opportunities for mechanistic studies and industrial cultivation.