Identification and characterization of a novel B-cell epitope on Aleutian Mink Disease virus capsid protein VP2 using a monoclonal antibody

Aleutian mink disease is caused by a highly contagious parvovirus (Aleutian mink disease virus, AMDV). This disease is one of the most commercially important infectious disease worldwide and causes considerable economic losses to mink farmers. The capsid protein VP2 is the major immunogenic antigenic protein of AMDV, and is involved in viral tropism, pathogenicity, and host selection. However, few reports have described the use of VP2-specific monoclonal antibodies (mAbs) in B-cell epitope identification and immunological detection. In this study, we produced a specific mAb, 1G5, against AMDV VP2 protein (amino acids: 200 ∼ 588) and characterized its specificity and relative affinity. Six partially overlapping truncated recombinant proteins and seven synthetized peptides were used to identify the epitopes recognized by 1G5. The results indicate that mAb 1G5 can distinguish AMDV, MEV and CPV2 with high affinity (Ka = 5.37 × 109), and the minimal linear epitope is located in amino acid residues 459EEEGWPAASGTHFED473. Sequence alignments demonstrated that the linear epitope was completely conserved among most Amdoparvoviruses except the bat parvovirus, where three substitutions (463W-463F, 466A-466G and 471F-471Y) were noted. Our results reveal that the identified epitope might be a common B-cell epitope of AMDV antibodies, and the 1G5 mAb can be used to identify the cleavage of the capsid proteins during AMDV infection. This is also the first report of a B-cell epitope on AMDV capsid protein VP2 (VP2: 459-473) using a mAb. These findings have potential applications in the development of new diagnostic tools for AMDV.