Susan B. Slemenda

Nosema ceranae n. sp. (Microspora, Nosematidae), morphological and molecular characterization of a microsporidian parasite of the Asian honey bee Apis cerana (Hymenoptera, Apidae)

Summary Based on light microscopic and ultrastructural characteristics as well as on the nucleotide sequence of the small subunit ribosomal RNA coding region, the microsporidium Nosema ceranae n. sp., a parasite of the Asian honey bee Apis cerana is described. Merogonial stages and sporonts are diplokaryotic. Merozoites are mostly formed by cytoplasmic fission in quadrinucleate meronts and the number of merogonial cycles may vary. The sporogony is disporoblastic. The living mature spore is ovocylindrical, straight to slightly curved and measures 4.7 × 2.7 μm whereas fixed and stained spores measure 3.6 × 1.7 μm. The polar filament is isofilar with a diameter of 96–102 nm and is arranged in 20–23 coils in the posterior and mid-part of the spore. In the anterior part of the polaroplast there are closely packed approximately 11 nm thick lamellae. The lamellae of the posterior polaroplast are thicker and less regular. In the posterior part of the mature spore a well fixed posterior body interpreted as a posterosome was often observed. Phylogenetic analysis, based on the sequence of the small subunit ribosomal RNA, places Nosema ceranae in the Nosema clade, as defined by Nosema bombycis , the type species of the Nosema genus.

Molecular characterisation of Babesia canis canis and Babesia canis vogeli from naturally infected European dogs.

The morphologically small Babesia species isolated from naturally infected dogs in Europe, Japan, and US are described as Babesia gibsoni despite the fact that molecular techniques show that they should be assigned to two or three separate taxons. The morphologically large Babesia isolated from dogs in Europe, Africa, and US were generally classified as B. canis until it was proposed to distinguish three related, albeit genetically distinct subspecies of this genus, namely B. canis canis, B. canis rossi, and B. canis vogeli. The insight into the molecular taxonomy of canine piroplasms is, however, limited because only partial small subunit ribosomal RNA (ssrRNA) sequence data exist for two species from the B. canis group. In this work, we molecularly characterised natural Babesia infections in 11 dogs from Croatia, France, Italy, and Poland. These infections were diagnosed as caused by B. canis canis and B. canis vogeli based on the analysis of the complete sequence of the ssrRNA genes. Phylogenetic analysis confirmed that the large Babesia species of dogs belong the to the Babesia sensu stricto clade, which includes species characterised by transovarial transmission in the tick vectors and by exclusive development inside the mammalian host erythrocytes. The new data facilitate the reliable molecular diagnosis of the subspecies of B. canis.

16S-like rDNA sequences from Developayella elegans, Labyrinthuloides haliotidis, and Proteromonas lacertae confirm that the stramenopiles are a primarily heterotrophic group

Summary A phylogenetic analysis of the 16S-like ribosomal RNA coding regions from Labyrinthuloides haliotidis, Developayella elegans, Proteromonas lacertae and other organisms corroborates morphological evidence that proteromonads and other eukaryotes with tripartite tubular hairs form a monophyletic group of organisms, the stramenopiles. Within the stramenopiles, the heterotrophic groups (proteromonads, Labyrinthulida, bicosoecids, Developayella and oomycetes) diverge before the radiation of the “heterokont algae”, the autotrophic stramenopiles. The stramenopiles were initially “protozoan” but their ecological success is largely attributable to the late symbiotic acquisition of chloroplasts. The stramenopiles and other taxa with chlorophyll a+c containing chloroplasts (cryptomonads, dinoflagellates, and haptophytes) do not share a common autotrophic ancestor. These photosynthetic assemblages acquired their plastids independently.

Babesia divergens-like Infection, Washington State

Most reported U.S. zoonotic cases of babesiosis have occurred in the Northeast and been caused by Babesia microti. In Washington State, three cases of babesiosis have been reported previously, which were caused by WA1 (for “Washington 1”)-type parasites. We investigated a case of babesiosis in Washington in an 82–year-old man whose spleen had been removed and whose parasitemia level was 41.4%. The complete 18S ribosomal RNA gene of the parasite was amplified from specimens of his whole blood by polymerase chain reaction. Phylogenetic analysis showed the parasite is most closely related, but not identical, to B. divergens (similarity score, 99.5%), a bovine parasite in Europe. By indirect fluorescent-antibody testing, his serum reacted to B. divergens but not to B. microti or WA1 antigens. This case demonstrates that babesiosis can be caused by novel parasites detectable by manual examination of blood smears but not by serologic or molecular testing for B. microti or WA1-type parasites.

Pulmonary microsporidiosis due to Encephalitozoon hellem in a patient with AIDS

The microsporidian Encephalitozoon hellem is being reported with increasing frequency in HIV-positive subjects, as an agent of disseminated microsporidiosis without involving the gastrointestinal tract. We describe a case of pulmonary microsporidiosis in a 27-year-old Italian man with AIDS who developed fever, cough, and dyspnea. A chest X-ray showed multiple bilateral pulmonary opacities and mediastinal lymph-node enlargement. Stained smears of bronchoalveolar lavage sediment showed oval structures consistent with microsporidian spores. Viral, bacterial and fungal cultures were repeatedly negative, whereas microsporidia were successfully cultured in human and bovine fibroblast cell lines. Analysis of electron micrographs indicated that the isolate belonged to the genus Encephalitozoon. Based on further immunological, biochemical and molecular studies it was characterized as E. hellem. Even though a temporary improvement with albendazole therapy was noticed, the patient deteriorated clinically and died of severe respiratory distress.

A longitudinal study of Babesia microti infection in seropositive blood donors

Babesia infection is caused by intraerythrocytic tick‐borne parasites. Cases of transfusion‐transmitted babesiosis have been increasingly recognized. To date, no Babesia test has been licensed for screening US blood donors. We conducted a longitudinal study to assess the course and markers of Babesia infection among seropositive donors identified in a seroprevalence study.