Tissue lesions of gill, spleen and trunk kidney post vaccination and challenge. Gibel carp were intramuscularly injected with pcCCL35.2/pcORF25, pcORF25, pcCCL35.2/Vaccine, Vaccine, pcCCL35.2, pcDNA3.1-neo, and PBS on Day 0, and intraperitoneally injected with CyHV-2 on 14 dpi. Gill, spleen and trunk kidney tissues were collected on 21 dpi, made slides, then stained by HE. Healthy gibel carp tissues were used as blank control. In gill, sloughing of the epithelial cells (SEC) and secondary branchial lamella curl (SBLC) were two main signs. In spleen, vacuolization and Karyorrhexis were two main symbols. In trunk kidney, hypertrophied nuclei and vacuolization were two main features.