Carp Edema Virus Infection Is Associated With Severe Metabolic Disturbance in Fish

Abstract

Significant mortalities associated with emerging viral diseases are challenging the economy of common carp aquaculture. As such, there is an increased need to disentangle how infected fish cope with progressive disease pathology and lose the ability for homeostatic maintenance of key physiological parameters. A natural carp edema virus (CEV) infection outbreak at a carp fish farm provided an opportunity to examine diseased and healthy carp in the same storage pond, thereby contributing to our better understanding of CEV disease pathophysiology. The disease status of fish was determined using PCR-based virus identification combined with analysis of gill pathology. Compared with healthy control carp, the blood chemistry profile of CEV-infected fish revealed major disruptions in electrolyte and acid-base balance (i.e., hyponatraemia, hypochloraemia, hyperphosphatemia, elevated pH, base excess, and anion gap and decreased partial dissolved carbon dioxide). In addition, we recorded hyperproteinaemia, hyperalbuminaemia, hypotonic dehydration, endogenous hyperammonaemia, and decreased lactate along with increased creatinine, alkaline phosphatase, alanine aminotransferase, and aspartate aminotransferase. Red blood cell associated hematology variables were also elevated. The multivariate pattern of responses for blood chemistry variables (driven by sodium, pH, partial dissolved carbon dioxide, ammonia, and albumin in the principal component analysis) clearly discriminated between CEV-infected and control carp. To conclude, we show that CEV infection in carp exerts complex adverse effects and results in severe metabolic disturbance due to the impaired gill respiratory and excretory functioning.

Characteristics of pathology and transcriptome profiling reveal features of immune response of acutely infected and asymptomatic infected of carp edema virus in Koi

“…The Koi infected with CEV exhibited floating heads, which is thought to be possibly due to hypoxia caused by damage to gill tissue. However, study had reported that the hemoglobin levels is rising during CEV infection (23), and fish have evolved this mechanism to cope with hypoxia (35). Severe impairment of osmoregulation was considered to be the potential cause of death of infected CyHV-3 (36).…”

“…Since the Koi infected with CEV causes severe gill injury, whether severe impairment of osmoregulation was also considered to be the potential cause of death of infected CEV. The mortality rate of common carp of CEV infection can be decreased using a long-term curative 0.5% salt water bath (37), and the osmotic balance associated with hyponatremia and hyperammonemia during CEV infection have been demonstrated (24), suggesting that osmotic pressure imbalance may also be a potential cause of CEV pathogenesis (23,24). Ammonia poisoning has a suppressive effect on innate immunity and affects the composition of immunoglobulin (38).…”

“…Gills are not only respiratory organs of fish, but also play an important role in osmotic pressure balance, metabolic function and immune function (22). Metabolomic analysis and blood biochemical indicators showed that the disease was accompanied by a severe disturbance of osmotic pressure balance, which was largely associated with impaired gill respiratory and excretory functions (23). In addition, the significantly down-regulation of CD4, TCRa2 and IgM in gill tissue suggests that complex host-pathogen interactions within the gills can have immunosuppressive consequences (24).…”

A Review of Emerging Goose Astrovirus Causing Gout

“…Several studies reported that when the dietary calcium content of goslings reached 3.1% (approximately 0.9% of normal), the imbalance of the ratio of calcium and phosphorus formed an ectopic deposition of calcium, resulting in poor urination [81][82][83]. In addition, studies have shown that the virus disrupts the host's electrolyte balance or acid-base balance, leading to nutrient imbalance and death [84][85][86][87]. The levels of 1α-hydroxylase and vitamin D receptor in lung tissues of mice infected with H9N2 avian influenza virus were reportedly significantly increased, which led to the increased calcium load in the kidney [88].…”

Carp edema virus infection associated gill pathobiome: A case report

“…Carp edema virus disease (CEVD), also known as koi sleepy disease (KSD), is a serious disease of common and koi carp. From its first confirmed occurrence in Europe (Great Britain) in 2009, CEVD has been recognized in virtually all countries where common carp or koi carp are bred (Jung‐Schroers et al, 2015; Pikula et al, 2021; Pragyan et al, 2019; Way et al, 2017). Previous observations documented that it often manifests as a multifactorial disease with several parasites, bacteria and/or viruses present on the gill mucosa or within internal organs (Lewisch et al, 2015; Adamek et al, 2018; Sauerwald et al, 2020).…”