Origin of the public memory antibody response induced upon antiviral vaccination in fish

In this work, we studied the modifications of the Ab repertoires following vaccination with an attenuated VHSV in rainbow trout. To this purpose, we set up a cDNA barcoded strategy to sequence the repertoire of IgM and IgT heavy chain transcripts corresponding to selected VH families. We show that the persisting memory response contains public IgM clonotypes. The vaccination also induces private responses for both IgM and the mucosal IgT, implicating clonotypes that are rare in naïve fish. This study provides an evolutionary perspective on the development of public antibody specificities potentially ensuring universal protection after infection.