VIP and Yersinia infectious disease: Before determining the effects that Yersiniosis had on the expression levels of cDNA encoding rainbow trout PACAP splicing variants (PACAP and PRP/PACAP) and VIP/PACAP receptor subtype 2 (VPAC2) in the spleen, head, kidney, and skin of rainbow trout, the presence of the disease was determined by visual examination, microbiological testing, and conventional PCR.