Pathophysiology of Ichthyophthirius multifiliis Infection in Rainbow Trout (Oncorhynchus mykiss) and Chub (Leuciscus cephalus)

Dual-Organ Transcriptomic Analysis of Rainbow Trout Infected With Ichthyophthirius multifiliis Through Co-Expression and Machine Learning

“…Several studies have reported on the existence of multiple types of cysteine proteases in I. multifiliis according to gelatin-precast zymography and genomic information from the macro-nucleus ( 7 , 64 – 66 ). These virulence factors can directly affect erythrocytes, thus inducing hemolysis and anemia, as shown in this study (decrease in Ht from 39 to 21% after I. multifiliis infection) as well as other studies ( 55 , 57 , 58 ). When erythrocytes are ruptured, excessive Fe 2+ and K + flow into the blood.…”

“…Also, genes linked to oxidative phosphorylation, the major metabolic pathway through which ATP is produced by cellular respiration, and the metabolism were strongly linked to significant responses to the infection in both organs (53,54). Abdel-Hafez et al (55) showed that liver glycogen can be depleted due to loss of osmoregulation during I. multifiliis infection, leading to a significant reduction in serum glucose levels, despite excessively high expression of metabolism-related and oxidative phosphorylation pathways. These transcriptomic responses with low glucose levels are the consequences of rapid energy depletion during I. multifiliis infection, and large expenditures of energy and metabolites could help to repair any damage and counteract the pathogen (56).…”

“…To invade the mucosal and epidermal layer, I. multifiliis can cause cellular destruction and histo-pathological changes such as necrosis, inflammation, and epidermal proliferation (7,55,63). Numerous proteases and lytic enzymes from parasites are wellknown virulence factors that can destroy host tissues, such as the extracellular matrix and interstitial tissues, through catabolism of host membranes and cytoadherence (64).…”

“…In addition, most pathways related to cell replication, such as the cell cycle, DNA replication, meiosis, mRNA surveillance, and spliceosome pathways, were among the top 10% most up-regulated KEGG pathways in the head kidney, though they did not among the top 10% of pathways in the liver during I. multifiliis infection. Severe anemia, pale gills, and low numbers of erythrocytes are known as the major clinical signs of I. multifiliis infection ( 55 , 57 , 58 ). Likewise, we observed not only pale gills during infection but significantly lower Ht in the Ich and/or R-Ich groups, which implies that the host was in a state of considerable erythrocyte deficiency.…”

Phylogenomic analyses reveal subclass Scuticociliatia as the sister group of subclass Hymenostomatia within class Oligohymenophorea

“…Examples include Ichthyophthirius multifiliis which is responsible for white spot disease in freshwater fishes (Abdel-Hafez et al, 2014;Forwood et al, 2014;Fu et al, 2014;Hoshino et al, 2014), and various species of scuticociliates that cause a range of diseases (collectively termed 'scuticociliatosis') in economically important host organisms Jin et al, 2010;Zhan et al, 2014).…”