Hematological and Histological Changes in Prussian Carp Carassius gibelio Infected with Cyprinid Herpesvirus 2

Abstract

Outbreaks of cyprinid herpesvirus 2 (CyHV-2) disease, also known as herpesviral hematopoietic necrosis, among cultured Prussian Carp Carassius gibelio has occurred each year in Jiangsu province, China, since 2009. In autumn 2014, hematological, blood biochemical, and histological changes in naturally infected moribund Prussian Carp were investigated after CyHV-2 was confirmed as the sole etiologic agent by etiological analyses. Total erythrocyte count, total leukocyte count, hemoglobin concentration, and thrombocyte count were significantly reduced (P < 0.01), whereas erythrocyte osmotic brittleness was significantly increased (P < 0.01) in infected fish compared with control fish. In addition, monocyte count was higher (P < 0.01) and lymphocyte count was lower (P < 0.01) in diseased fish than in control fish. The blood biochemical analyses indicated significant increases (P < 0.01) in the activities of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and lactate dehydrogenase as well as in the levels of total protein, globulin, total bilirubin, creatinine, and urea along with significant decreases (P < 0.01) in glucose and albumin in the diseased group. Histopathological examinations indicated that the kidneys and spleens of moribund Prussian Carp were the most severely lesioned organs, followed by the gills and hearts. Hypertrophied nuclei with marginated chromatin also appeared in the hearts and renal tubular epithelia from diseased fish. Pathological analysis of blood cells showed that approximately 78% of erythrocytes and 94% of leukocytes were lesioned with different levels of degeneration and necrosis in the diseased group. These previously unreported observations may be useful in the diagnosis of CyHV-2 disease. Received May 11, 2015; accepted March 24, 2016.

Alterations of Plasma Biochemical and Immunological Parameters and Spatiotemporal Expression of TLR2 and TLR9 in Gibel Carp (Carassius auratus gibelio) after CyHV-2 Infection

“…In our study, the level of glucose in plasma descended continuously upon infection with CyHV-2. Similar lower glucose levels in plasma have been observed in various species of fish following pathogens' infection [24,30]. Plasma TP plays crucial roles in osmotic pressure maintenance and metabolite transport, and its levels are a reflection of nutritional metabolism and non-specific immunological function [31].…”

“…Blood parameters can accurately reflect the disease progress of fish during pathogen invasion. Previous studies have described the plasma indicators of moribund gibel carp naturally infected with CyHV-2 [1,24], but these studies were limited to certain time points and specific plasma indicators of viral infection. Moreover, little research has been carried out on metabolic enzymes, biochemical indicators, as well as innate and adaptive immune factors of gibel carp in plasma following experimental infection with CyHV-2.…”

Cyprinid herpesvirus‐2 (CyHV‐2): a comprehensive review

“…Hypertrophied nuclei of cardiac muscle cells containing marginated chromatin were reported in another study (Lu et al . 2016). Similarly, multiple focal necroses and necrotic area with enlarged nuclei and prominent chromatin margination has been reported in heart, small intestine, pancreas and skin by Chang et al .…”

Circulatory physiology and erythropoiesis in freshwater fish Labeo rohita experimentally parasitized by Argulus bengalensis

“…Lymphopenia was also observed in Oreochromis niloticus challenged with Vibrio parahaemolyticus (Balfry et al, 1997) and in Oncorhynchus mykiss challenged with Vibrio anguillarum (Lamas et al, 1994). Lymphopenia is known to hamper antibody production (Lu et al, 2016) and cellular immunity as well, hence resulting in further manifestation of the disease condition and very often leading to secondary infection (Ruane et al, 1999). At the initial phase of parasitaemia, development of neutropenia could be correlated with parasitic stress.…”