Hematology of koi (Cyprinus carpio) infected with koi herpesvirus (KHV)

Abstract

Koi (Cyprinus carpio, mean body weight=10 g) was experimentally infected with koi herpesvirus (KHV) by intraperitoneal injection with undiluted supernatants from KF-1 cell cultures showing cythopathic effect (CPE) 7 days post-KHV inoculation at a dose of 100 μL per fish and the changes in hematological and plasma chemistry parameters due to the viral infection were measured. Fish were sampled initially and at 1, 3, 6, 9 and 11 days post-infection. Among the plasma chemistry parameters, total protein, hemoglobin and albumin were slightly higher in the control compared to the infected group. However, no clear differences were seen in the hematological parameters between the groups. When values were grouped according to infection stages (incubation period [IP]; onset/peak of mortality [OP]; recovery [R]), hemoglobin and the percentage of neutrophils were higher while platelet count was lower in the control group at IP, whereas no marked differences were observed among plasma chemistry parameters. At OP, most hematological parameters such as hematocrit, hemoglobin and percentage of neutrophils were higher while RBC and platelet count were lower in the infected group compared to the control. Plasma chemistry parameters such as total protein, albumin and Mg were likewise lower in the infected group. The preliminary results indicate that changes in the hematological and plasma chemistry parameters in response to KHV infection could be used to aid the diagnosis of KHV infection in koi.