In order to delve into the molecular mechanism underlying the increased pathogenicity of the recombinant Muscovy duck parvovirus(rMDPV)towards Muscovy ducklings,two sub-genom-ic fragments of the rMDPV strain ZW were cloned into the plasmid pBluescript Ⅱ(SK)to gener-ate the recombinant plasmid pZW.A single nucleotide mutation was engineered in the VP3 gene of pZW to discriminate from the parental strain ZW.pZW plasmid-lipid complex was transfected into the chorioallantoic membrane of 11-day-old embryonated Muscovy duck embryos,resulting in res-cue of infectious virus,rZW,carrying the genetic marker.The rescued virus was passaged in 12-day-old embryonated Muscovy duck embryos and exhibited the similar medium embryo lethal dose(ELD50)value and growth curve compared to the parental strain ZW.Both rZW and strain ZW led to 100％mortality in the infection tests performed with 3-day-old Muscovy duckling.Postmortem necropsy revealed a characteristic intestine embolism formed in the rZW-infected ducklings.Taken together,the generation of the infectious clone pZW lays a solid foundation for deciphering the pathogenesis of rMDPV.

In order to delve into the molecular mechanism underlying the increased pathogenicity of the recombinant Muscovy duck parvovirus(rMDPV)towards Muscovy ducklings,two sub-genom-ic fragments of the rMDPV strain ZW were cloned into the plasmid pBluescript Ⅱ(SK)to gener-ate the recombinant plasmid pZW.A single nucleotide mutation was engineered in the VP3 gene of pZW to discriminate from the parental strain ZW.pZW plasmid-lipid complex was transfected into the chorioallantoic membrane of 11-day-old embryonated Muscovy duck embryos,resulting in res-cue of infectious virus,rZW,carrying the genetic marker.The rescued virus was passaged in 12-day-old embryonated Muscovy duck embryos and exhibited the similar medium embryo lethal dose(ELD50)value and growth curve compared to the parental strain ZW.Both rZW and strain ZW led to 100％mortality in the infection tests performed with 3-day-old Muscovy duckling.Postmortem necropsy revealed a characteristic intestine embolism formed in the rZW-infected ducklings.Taken together,the generation of the infectious clone pZW lays a solid foundation for deciphering the pathogenesis of rMDPV.