Enterospora canceri n. gen., n. sp., intranuclear within the hepatopancreatocytes of the European edible crab Cancer pagurus

Abstract

Only 1 genus (Nucleospora) within 1 family (Enterocytozoonidae) of the Microsporidia contains species that are parasitic within the nuclei of their host cells; to date, all described intranuclear Nucleospora spp. parasitise fish. This study describes the first intranuclear microsporidian parasite of an invertebrate, the European edible crab Cancer pagurus L. (Decapoda: Cancridae). Infected crabs displayed no obvious external signs, and maximum apparent prevalence of infection within a monthly sample was 3.45%. Infected hepatopancreatic tubules were characterised by varying numbers of hypertrophic and eosinophilic nuclei within epithelial cells. Parasite stages appeared as eosinophilic granular accumulations causing margination of host chromatin. In advanced cases, the tubule epithelia degenerated, with parasites and sloughed epithelial cells appearing in tubule lumens. All life stages of the parasite were observed within host nuclei. Uninucleate meronts were not detected, although binucleate stages were observed. Multinucleate plasmodia (sporogonal plasmodia) contained up to 22 nuclei in section, and late-stage plasmodia contained multiple copies of apparatus resembling the polar filament and anchoring disk, apparently associated with individual plasmodial nuclei. As such, aggregation and early assembly of sporoblast components took place within the intact sporogonial plasmodium, a feature unique to the Enterocytozoonidae. Liberation of sporoblasts from plasmodia or the presence of liberated sporoblasts was not observed in this study. However, large numbers of maturing and mature spores (measuring 1.3 ± 0.02 × 0.7 ± 0.01 µm) were frequently observed in direct contact with the host nucleoplasm. Considering the shared features of this parasite with microsporidians of the family Enterocytozoonidae, and the unique presence of this parasite within the nucleoplasm of decapod crustacean hepatopancreatocytes, this parasite (Enterospora canceri) is proposed as the type species of a new genus (Enterospora) of microsporidian. Molecular taxonomic work is now required, comparing Enterospora to Enterocytozoon and Nucleospora, the 2 other genera within the Enterocytozoonidae.KEY WORDS: Cancer pagurus · Crustacea · Enterocytozoon · Enterocytozoonidae · Epithelium · Hepatopancreas · Intranuclear · Nucleospora · Nucleoplasm · Nucleus Resale or republication not permitted without written consent of the publisherDis Aquat Org 75: [61][62][63][64][65][66][67][68][69][70][71][72] 2007 (Modin 1981, Elston et al. 1987, Mullins et al. 1994, Nilsen et al. 1995, Lom & Dyková 2002. The family also contains the genus Enterocytozoon, known to infect a range of mammalian and bird hosts. Although these parasites associate intimately with the host cell nuclei, intranuclear infections have not been described to date. Members of the genera Enterocytozoon and the fish-infecting Nucleospora exhibit significant structural and genetic differences from other microsporidians and are placed amongst the basal groups of the Microsporidia (Lo...

Enterospora sp., an intranuclear microsporidian infection of hermit crab Eupagurus bernhardus

“…One specimen from the 30 assessed showed a severe degeneration of the hepatopancreas typical for that described previously in Cancer pagurus infected with the intranuclear microsporidian Enterospora canceri (Stentiford et al 2007). The normal tubular structure of the hepatopancreas was almost entirely destroyed, with detachment of epithelial cells from the tubule basement membrane, a liberation of presumably free parasite spores to the tubule lumen and a pronounced haemocytic encapsulation response to affected tubules.…”

Cancer pagurus bacilliform virus (CpBV) infecting juvenile European edible crabs C. pagurus from UK waters

“…Several pathogens of commercial and ecological significance have been described in C. pagurus from the English Channel fishery, including Hematodinium spp. (Stentiford et al 2002), Enterospora canceri (Stentiford et al 2007) and a Paramarteilia sp. (G. D. Stentiford unpubl.…”

“…Several protistan pathogens have been described from English Channel stocks of Cancer pagurus (Stentiford et al 2002(Stentiford et al , 2003(Stentiford et al , 2007. However, to date, only one virus, C. pagurus systemic bunya-like virus (CpSBV), has been described from the Cancer genus (Corbel et al 2003).…”

Disease will limit future food supply from the global crustacean fishery and aquaculture sectors

“…In some cases, microsporidium infections of crustacean hosts have been demonstrated to have close relationships with those found infecting vertebrate hosts (e.g. Enterospora in marine crabs, Stentiford et al, 2007, providing evidence for multi-trophic transfer between invertebrates and vertebrates. Finally, decapod crustaceans are infected by a wide variety of metazoan parasite life stages.…”