Identification of a conserved neutralizing linear B-cell epitope in the VP1 proteins of duck hepatitis A virus type 1 and 3

- A common neutralizing epitope of DHAV-1 and DHAV-3 was recognized by the mAb 4F8.
- The epitope of 75GEIILT80 in VP1 was conserved among different DHAV-1 strains.
- The epitope of 75GEVILT80 in VP1 was conserved among different DHAV-3 strains.

Duck virus hepatitis (DVH), mainly caused by duck hepatitis A virus (DHAV), is a severe disease threaten to duck industry and has worldwide distribution. As the major structural protein, the VP1 protein of DHAV is able to induce neutralizing antibody in ducks. In this study, a monoclonal antibody (mAb) 4F8 against the intact DHAV-1 particles was used to identify the possible epitope in the three serotypes of DHAV. The mAb 4F8 had weak neutralizing activities to both DHAV-1 and DHAV-3, and reacted with the conserved linear B-cell epitopes of 75GEIILT80 in DHAV-1 VP1 and 75GEVILT80 in DHAV-3 VP1 protein, respectively, while not with DHAV-2 VP1. This was the first report about identification of the common conserved neutralizing linear B-cell epitope of DHAV-1 and DHAV-3, which will facilitate understanding of the antigenic structure of VP1 and the serologic diagnosis of DHAV infection.