Generation of an infectious clone of AMDV and identification of capsid residues essential for infectivity in cell culture

•Pathogenic strains of AMDV, such as Utah-1, do not replicate in cell culture.•In this study, we constructed a full-length infectious clone (pADV-G).•Four virulence-associated residues of pADV-G VP2 were studied by mutagenesis.•Mutation of H92 or Q94 decreased transcription and replication.•VP2 residues 92 and 94 are critical for AMDV replication in vitro.

Pathogenic strains of Aleutian mink disease virus (AMDV) such as Utah-1 do not replicate in cell culture (e.g., Crandell Rees feline kidney cells) while the in vitro-adapted AMDV strain ADV-Gorham (ADV-G) is not pathogenic. Here, we constructed a full-length infectious clone (pADV-G). Alignment of the VP2 gene of ADV-G with that of other AMDV strains revealed many amino acid (a.a.) residues conserved among pathogenic isolates that differed in ADV-G. Four virulence-associated, conserved residues of pADV-G VP2 were studied by site-directed mutagenesis (H92A, Q94S, Y115F, and I116L). Mutation of residue 92 or 94 decreased viral-transcription and viral-infectivity levels, whereas mutation of residue 115 or 116 did not affect viral-infectivity in CRFK cells. These results indicated that VP2 residues 92 and 94, both located on the surface of the viral capsid, are critical for AMDV infectivity in vitro.