Isolates of Encephalitozoon cuniculi from farmed blue foxes ( Alopex lagopus ) from Norway differ from isolates from Swiss domestic rabbits ( Oryctolagus cuniculus )

Abstract

Encephalitozoon cuniculi has a wide host range among mammals, but whether it represents a homogeneous species is a subject of controversy. We have isolated, cultivated (in human MRC-5 cells) and, for the first time, characterized by immunological and molecular biological methods four isolates of E. cuniculi from Norwegian blue foxes with a history of encephalitozoonosis. The isolates were compared with nine isolates from domestic rabbits from Switzerland. Two E. cuniculi subtypes were identified according to their host species. A 5'-GTTT-3' tetranucleotide repeat was present twice in the rDNA intergenic spacer in all isolates from foxes as opposed to three times in all isolates from rabbits. Furthermore, random amplified polymorphic DNA analysis showed one polymorphic band among the subtypes, and Western-blot analysis using serum from an infected fox discriminated between the two subtypes on the basis of their banding patterns in the ranges of 31-33 and 38-40 kDa. The 5'-GTTT-3' tetranucleotide repeat is a valuable genetic marker for these two subtypes of E. cuniculi and will be of use in continued studies on the molecular epidemiology of this parasite.

Zoonotic Potential of the Microsporidia

“…The authors suggested that mice are a potential "reservoir" of E. cuniculi for arctic foxes and feral minks. Indeed, recent molecular characterization of E. cuniculi isolates from Norway and Finland (8,190) revealed that all foxes originating from four different farms were infected with strain II ("mouse strain") of E. cuniculi (see "Molecular Epidemiology" below).…”

“…In captive carnivores, disseminated infections similar to those found in dogs occurred in fox cubs (215). This disease, which is still a major problem and causes heavy losses of blue foxes in northern European countries (5), is caused by strain II ("mouse strain") of E. cuniculi (190).…”

Survey for Encephalitozoon cuniculi in Arctic Foxes (Alopex lagopus) in Greenland

“…Molecular studies have identified three strains of E. cuniculi (Didier et al, 1995). One strain was isolated from rabbits and humans, another from arctic foxes and mice, and a third from dogs and humans (Hollister et al, 1996;Mathis et al, 1996Mathis et al, , 1997.…”

“…Soluble antigen from E. cuniculi isolated from a blue fox (Mathis et al, 1996) was coated to microtiter plates. The serum samples were diluted 1:100 in phosphate buffered saline (PBS: 170 mM, pH 7.4), with tween 20 (50 g/ml) and skimmed milk (30 mg/ml), and were added to two wells each.…”

Serological investigation of canine encephalitozoonosis in Norway

“…Strain I was isolated from rabbits in Europe and North America. Strain II was found in rodents (mouse, rat) and blue foxes in Europe, while strain III was found in dogs in North America and South Africa (Didier et al 1995;Mathis et al 1996). Both the rabbit (I) and the dog (III) strains have been identified in HIV-positive patients; and rabbits were susceptible to these isolates at experimental infection (Mathis et al 1997).…”