Development of the PKX myxosporean in rainbow trout Salmo gairdneri

Abstract

Sequenhal development of PKX, the causative agent of prohferahve h d n e y dlsease, is descnbed in rainbow trout Salmo ga~rdnen hchardson by light and electron mlcroscopy Fish were exposed to water contaming the infechous stage of PKX and the parasite was detected 3 wk later Parasites were prominent the following week and they mulhplied by endogeny, binary fission and possibly plasmotomy in the blood and h d n e y intershhum Intershbal nephnbs that is typically assoclated \nth PKD was fust observed 5 wk after exposure and was most prominent between 8 to 11 wk At 7 wk parasites were found in the lumens of the tubules, many were daughter cells released from PKX Myxosporean sporoblasts formed within these daughter cells (enveloping cells) The sporoblasts consisted of 6 cells and some organized into spores w~t h 2 spherical polar capsules Although the spores persisted for several months after the interstitial PKX and assoclated inflammation had subsided they dld not complete their development They remained within the enveloping cell and apparently dld not form complete valves Because only incomplete spores were observed salmonids may be abnormal hosts and the preclse taxonomic status of PKX was not determined Epizoohological and sequential development data support the hypothesis that the interstitial form of PKX and the intraluminal myxosporeans belong to the same organism

Complex interaction between proliferative kidney disease, water temperature and concurrent nematode infection in brown trout

“…Therefore, comparable to our results gained from experimental studies, PKD prevalence and the composition of pathological lesions in infected YOY were not associated with water temperature. It has previously been shown that rainbow trout surviving the clinical phase of PKD are able to completely regenerate renal morphology and that this process is not influenced by water temperature (Ferguson 1981, Kent & Hedrick 1985, Clifton-Hadley et al 1987, Schmidt-Posthaus et al 2012. In accordance with these findings, in our study fish from all tributaries, independent of summer-warm or summercool water, renal morphology could be completely restored during the winter months.…”

“…T. bryosalmonae infects fish through the skin and gills , Longshaw et al 2002. After invasion, this parasite is distributed systemically, with the kidney as the main target organ (Kent & Hedrick 1985). Here, T. bryo salmonae multiplies and differentiates from extra sporogonic stages, mainly in the renal interstitium, to sporogonic stages in the tubular lumen.…”

Light and electron microscopic studies on the development of Hoferellus carassii (Myxosporea), the causative organism of kidney enlargement disease of goldfish.

“…Recently, Hoferellus cyprini (LOM andDYKOVA, 1985, MOLNAR and), Sphaerospora sp. (FISCHER-SCHERL et al, 1986), "PKX" (KENT and HEDRICK, 1986) and Myxobilatus legeri (MOLNAR, 1988) have also been reported as having intracellular stages. Moreover, DANIELS et al (1976) showed intra cellular parasites in the epithelium of rainbow trout exposed to water containing some stage of Myxobolus cerebralis.…”

Oral administration of Fumagillin DCH protects chinook salmon Oncorhynchus tshawytscha from experimentally-induced proliferative kidney disease

“…The severe inflammation of the kidney that characterizes the disease is caused by PKX, the vegetative stage of a poorly understood myxozoan (Kent & Hedrick 1986). Although the precise taxonomic position of PKX has not been determined, recent observations by Hedrick e t al.…”