To investigate the transcriptional regulatory mechanism underlying the upregulation of PADI2 expression after MO infection, we downloaded the sequence within 2000 bp upstream of PADI2 from the National Center for Biotechnology Information and used the transcription factor online prediction website AnimalTFDB4 v4.0 to search for transcription factors that may bind to the upstream promoter region of PADI2 (Additional file 8). This evidence concerns the gene PADI2 and infection.