Transmission of Tetracapsuloides bryosalmonae (Myxozoa: Malacosporea) to Fredericella sultana (Bryozoa: Phylactolaemata) by various fish species

Abstract

Tetracapsuloides bryosalmonae is a myxozoan parasite of salmonids and freshwater bryozoans, which causes proliferative kidney disease (PKD) in the fish host. To test which fish species are able to transmit T. bryosalmonae to bryozoans, an infection experiment was conducted with 5 PKD-sensitive fish species from different genera. Rainbow trout Oncorhynchus mykiss, brown trout Salmo trutta, brook trout Salvelinus fontinalis, grayling Thymallus thymallus and northern pike Esox lucius were cohabitated with T. bryosalmonae-infected Fredericella sultana colonies and then subsequently cohabitated with statoblast-reared parasite free Bryozoa. Statoblasts from infected colonies were tested by PCR to detect cryptic stages of T. bryosalmonae, which may indicate vertical transmission of the parasite. In this study, brown trout and brook trout were able to infect Bryozoa, while there was no evidence that rainbow trout and grayling were able to do so. Few interstitial kidney stages of the parasite were detected by immunohistochemistry in brown trout and brook trout, while rainbow trout and grayling showed marked proliferation of renal interstitial tissue and macrophages with numerous parasite cells. Intraluminal stages in the kidney tubules were only detected in brown trout and rainbow trout. In contrast to previous observations, pike was not susceptible to PKD in these trials according to the results of T. bryosalmonae-specific PCR. No DNA of T. bryosalmonae was detected in any statoblast.KEY WORDS: Tetracapsuloides bryosalmonae · Myxozoa · Malacosporea · Bryozoa · Proliferative kidney disease · PKD · Host specificity · Transmission experiment Resale or republication not permitted without written consent of the publisherDis Aquat Org 79: [133][134][135][136][137][138][139] 2008 the parasite using brown trout Salmo trutta, in the study of Tops et al. (2004), no infection of Bryozoa could be achieved with PKD-infected brown trout, rainbow trout Oncorhynchus mykiss or chinook salmon O. tschawytscha. It remains unknown in which fish host species T. bryosalmonae can form mature spores infective for Bryozoa. In the present study, different fish species were tested for the first time under laboratory conditions for their susceptibility to PKD and their subsequent capability to transmit T. bryosalmonae back to Bryozoa. We also took into account the possibility that the presence of cryptic parasite stages in bryozoan statoblasts could cause an overt infection when colonies start to grow. MATERIALS AND METHODSFish. Rainbow trout of the American Trout Lodge strain were raised from eggs in our specific pathogenic free (SPF) wet lab. Brown trout, brook trout and grayling were obtained as SPF fingerlings from 2 Bavarian hatcheries. Pike (10 to 15 cm) were obtained from a Bavarian hatchery. All fish were young of the year. Fish were maintained in aquaria with flowthrough dechlorinated tap water and fed on commercially available fish food or live fish (pike only) until they reached a size of 9 to 15 cm.Bryozoa. Infected bryozoa...

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

“…However, translocation into the tubular lumen was not obvious in the latter study, as elimination of T. bryo salmonae seemed rather to be taking place through degeneration of the parasites in the interstitium than by translocation into the tubular lumen (Bettge et al 2009, Schmidt-Posthaus et al 2012. These species differences were also shown by Morris & Adams (2006) and Grabner & El-Matbouli (2008), who were only able to demonstrate excreted spores in brown Salmo trutta and brook trout Salvelinus fontinalis, but not in rainbow trout. Similar to our results in rainbow trout, showing degenerated T. bryosalmonae in the renal interstitium, brown trout originating from the Lyssbach also showed IHC-positive, mainly degenerated, T. bryosalmonae in the renal interstitium of age 1+ individuals.…”

New phylogenomic and comparative analyses provide corroborating evidence that Myxozoa is Cnidaria

“…Generally, myxozoans undergo complex life cycles, with alternative life cycles incorporating a vertebrate host and an invertebrate host (Canning and Okamura, 2004;Lom and Dykova, 2006). The life cycles of most myxozoans are unknown and have been described for only one malacosporean, Tetracapsuloides bryosalmonae (Grabner and El-Matbouli, 2008;Morris and Adams, 2006;Tops et al, 2004), and less than 40 myxosporeans (Lom and Dykova, 2006). The myxosporean Thelohanellus kitauei is a pathological parasite that infects carp (of the family Cyprinidae), the most important cultured freshwater fish species in the world, and causes intestinal giant cystic disease (IGCD) (Kitaue, 1980).…”

Transmission Biology of the Myxozoa

“…However, in some fish species sporogonic stages seem to persist after clinical infection and possibly continue to form spores chronically (Kent et al, 1998, Kent et al, 2000. Recently it was shown by transmission experiments conducted with European parasite lineages that brown trout and brook trout (Grabner & El-Matbouli, 2008) can transmit the parasite to bryozoans. In contrast, rainbow trout and grayling became infected, but no infection appeared in bryozoans cohabitated with these fish.…”