Although viruses are important biological agents and useful molecular tools, little is known about the viruses of parasites. We report here the discovery of a candidate for an RNA virus in a kinetoplastid parasite. This potential virus, which we term LR1, is present in the promastigote form of the human pathogen Leishmania braziliensis guyanensis CUMC1-1A but not in 11 other stocks ofLeishmania that were examined nor in Trypanosoma brucei. The candidate viral RNA has a size of -6000 nucleotides, is single-stranded, and is largely, if not exclusively, located in the cytoplasm. No homologous LR1 sequences are detected in genomic DNA. The candidate viral RNA is associated with a spherical particle 32 nm in diameter that has a sedimentation coefficient of =130 S. There is as yet no evident effect of this potential virus on parasite physiology or the disease caused by the parasite.The presence of viruses in parasitic protozoa may be relevant to the diseases caused by these organisms and may be useful for molecular biological studies. DNA viruses have been reported in Amoeba (1) and virus-like particles have been observed in several Plasmodium species (1), in Nagleria (1), in Endotrypanum (2), in the cytoplasm of Leishmania hertigi (3, 4), and in the flagellum of Trypanosoma melophagium (5). Double-stranded RNA viruses have been found in Giardia (6) and Trichomonas (7). In addition, circular DNAs have been detected in Leishmania (8).We report here the discovery and preliminary characterization of a multicopy RNA in the cytoplasm ofLeishmania braziliensis guyanensis that is associated with a spherical particle 32 nm in diameter. This may be an RNA virus, to the best of our knowledge, the first virus found in a kinetoplastid parasite.MATERIALS AND METHODS Organisms. The Leishmania stocks examined in this study are shown in Table 1. They were grown as the promastigote forms at 28°C as described (9).Nucleic Acid Isolation. Total cellular RNA was prepared by the urea/phenol/cesium chloride method (10). Genomic DNA was prepared as described in Milhausen et al. (11). Gel purified LR1 RNA was prepared from 1.35 x 1010 L. braziliensis guyanensis CUMC1-1A cells by lysis in 5 ml of 1% NaDodSO4/proteinase K (1 mg/ml)/25 mM EDTA for 1 hr at 50°C. Chromosomal DNA was removed by potassium acetate precipitation and the supernatant was precipitated with 1-propanol, resuspended, and electrophoresed in a 0.7% agarose gel in TBE (89 mM Tris borate, pH 8.3/2 mM EDTA). The 6000-nucleotide band was excised from the gel, reelectrophoresed, electroeluted, and ethanol-precipitated.Electrophoresis and Hybridizations. Pulse-field gel electrophoresis was performed as described (9). RNA was electrophoresed either in 1.2% agarose/2.2 M formaldehyde gels as described (10) or in native 0.6% agarose gels in TBE at 1.8 V/cm for 12-16 hr. After electrophoresis RNA was treated with 50 mM NaOH for 30 min and transferred to a Nytran membrane (Schleicher & Schuell) (10). Hybridization to the LR1 cDNA riboprobe was carried out in 50% (vol/vol) formam...

We describe a 54-year-old spleen-intact man with transfusion-associated Babesia microti infection after a heart transplant. Adult respiratory distress syndrome developed in the patient, and he required mechanical ventilation. Our experiences with this patient suggest that babesiosis should be considered in the differential diagnosis of transplant patients who have fever and hemolytic anemia.

Enzymatic surface iodination and biosynthetic labeling with [35S]methionine, combined with immunoprecipitation by sera from patients with different forms of Leishmaniasis revealed a 65,000 Mr glycoprotein as the immunodominant moiety in promastigotes and amastigotes of the nine Leishmania species and isolates examined. Sera from patients with one form of Leishmaniasis recognized this component strongly, not only in the homologous, but also in the heterologous species. In addition to the crossreactivity displayed by immune sera, the 65,000 Mr glycoprotein (gp) common to all Leishmania species presented a characteristic shift to Mr 50,000 when samples were run in sodium dodecyl sulfate-polyacrylamide gel electrophoresis under nonreducing conditions. These results are in agreement with our previous studies (7), where a simple and similar profile was obtained for several geographic isolates of L. donovani, with a major surface glycoprotein of 65,000 Mr displaying the same characteristics described here. The structural similarity of the major 65,000 Mr gp of the six Leishmania species was demonstrated by Cleveland mapping. It is suggested that immunological specificities may be contributed by minor differences in glycosylation of this molecule. In keeping with recent data (13-15), where strong cross protection among different Leishmania species has been obtained by prophylactic immunization with irradiated whole promastigotes, this glycoprotein may be a good candidate for an antigen to be used for immunoprophylaxis of all forms of Leishmaniasis.

The parasitic protozoan Leishmania mexicana amazonensis has two developmental stages: a motile flagellated promastigote stage and a sessile intracellular amastigote stage. In our previous work, cells of the promastigote stage were found to synthesize more tubulin protein than those of the amastigote stage. Here, tubulin mRNAs in these leishmanias were analyzed. Based on dot blot hybridization between total leishmanial RNA and tubulin-specific cDNA probes derived from chicken brain, amastigotes and promastigotes were found to have approximately equal amounts of alpha- and beta-tubulin mRNAs. RNA blotting of leishmanial RNA, using chicken tubulin cDNA probes, showed that amastigotes and promastigotes both gave a single mRNA species of 2100 nucleotides for alpha-tubulin in roughly similar quantities. However, such analysis for beta-tubulin revealed mainly a single mRNA species of 3600 nucleotides for amastigotes and three species of 2800, 3600, and 4400 nucleotides for promastigotes, the smallest mRNA being the most predominant. Thus, regulation of gene expression appears to be different only for beta-tubulin between the two developmental stages of this protozoan.