Numerous antibody proteins were found upregulated in JE samples, included immunoglobulin J chain (IGJ) and Ig kappa chain V–I region (IGKV1–12) (Fig. 2A, Additional file 2: Fig. S2C, E, Additional file 3: Fig. S3A, B, Additional file 8: Table S2). Here, JCHAIN is linked to Japanese encephalitis.