In vitro susceptibility of sea lion poxvirus to cidofovir

Parapoxviruses of seals and sea lions are commonly encountered pathogens with zoonotic potential. The antiviral activity of the antiviral compounds isatin-beta-thiosemicarbazone, rifampicin, acyclovir, cidofovir and phosphonoacetic acid against a parapoxvirus (SLPV-1) isolated from a Californian sea lions (Zalophus californianus) was evaluated. Cidofovir was able to reduce virus-induced cytopathic effect of SLPV-1 in confluent monolayers when used in concentrations greater than 2 μg/ml. A decreasing virus yield was observed in the presence of increasing concentrations of cidofovir, which confirmed the ability of cidofovir to inhibit SLPV-1 replication. The in vitro efficacy of cidofovir against SLPV-1 indicates the therapeutic potential of cidofovir for the treatment of infections of humans and pinnipeds with parapoxviruses of seals and sea lions. This study confirms the previously proposed therapeutic potential of cidofovir for the treatment of parapoxvirus infections.