The Journal of protozoology最新文献

Pneumocystis carinii gp120 can elicit a specific T-cell proliferative response in mice after immunization with a gp120 preparation or with a crude P. carinii homogenate. It can also elicit a proliferative response from SCID mice after recovery from natural infection with P. carinii, implicating this glycoprotein as an important antigen in the host's response to P. carinii infection.

Antigenic sites on Pneumocystis carinii, the basis for organism enumeration by an enzyme-linked immunosorbent assay (ELISA) were adversely affected by incubation in detergents. However, stronger detergent concentrations were needed to eliminate high levels of non-specific background. Good P. carinii quantification was obtained with low non-specific background when the detergent was used only in the washing steps and not in cell suspension solutions. Formalin fixation of the cells resulted in good ELISA quantification of organism numbers with low non-specific background. No adverse effects were observed using a detergent on fixed cells. Although the system's range of accuracy needs to be expanded, a reduction in the number of organisms in response to the effects of pentamidine in vitro could be demonstrated by ELISA.

Ultrastructural examination of Pneumocystis grown on WI-38 human embryonic lung fibroblasts and treated with primaquine indicated progressive deterioration of cellular morphology. Thus, primaquine had a cidal effect on the organisms.

Nosema locustae, a microsporidian parasite of locusts and grasshoppers, was successfully propagated in a fat body cell line from Mythimna convecta (BPMNU-MyCo-1). The fat body cells were grown in MGM-448 medium supplemented with 5% fetal bovine serum and 3% Bombyx mori serum at 25 degrees C. Cultures were inoculated with Nosema spores and agitated for 2 min. Infection appeared 3 days post-inoculation and by 7th day, some cells were filled with spores. At the 15th day post-inoculation, 32% of the fat body cells were infected. After isolation, the spore yield ranged from 1.4 x 10(6) spores/ml. Infected cells were subcultured and by the 4th passage spore production decreased. Harvested spores were found infectious to Locusta migratoria.

Signals obtained from serial dilutions of rat-derived Pneumocystis carinii DNA were used to assess the sensitivity of a 650-bp DNA probe which recognises both cystic and non-cystic forms. Enhanced chemiluminescence was selected as a non-radioactive detection method and signals could be semi-quantitated by scanning densitometry. This technique was used to examine the inhibitory effect of pentamidine in vitro indicating that DNA probes might be useful tools in the search for a novel therapeutic agent.

Pneumocystis carinii trophozoites grow in vivo in close contact with host cells. The attachment of Pneumocystis to the lung cells seems to be a critical step in the parasite's development. Up to now, the contact of Pneumocystis with mammalian tissue culture cells was shown using light and scanning electron microscopy. The methods are not sufficient to observed in detail the parasite-feeder cell area of contact. In this work, the attachment of Pneumocystis trophozoites to feeder cells was examined in serial sections using transmission electron microscopy. When the contact of a trophozoite with a feeder cell took place, the development of filopodia penetrating deeply into invaginations of the feeder cell plasma membrane was observed. Then, the apical tips of filopodia become bulged anchoring the parasite to the feeder cell. The behaviour of Pneumocystis in feeder cell cultures is compared to that of the parasite in other in vitro or in vivo experimental models.

Cryptosporidium, a protozoan parasite of man and animals, is an important etiological agent of diarrhea throughout the world, particularly in children and immunocompromised individuals such as AIDS patients. Unfortunately, because of the lack of both in vivo laboratory models and reliable in vitro parasite culture systems, virtually nothing is known about the immunological events occurring during disease. In order to identify reliable animal models for infection, we studied C. parvum infections in 19 different strains of mice representing 12 H-2 haplotypes: A/J, AKR/J, B10.D2/J, B10.M/J, C3H/HeJ, C57BL/65, C57BL/6J-bgJ, CBA/NJ, DBA/1J, DBA/2J, HRS/J, HTG/J, NZB/B1NJ, NZW/J, P/J, RIII/J, SJL/J, SWR/J, and WB/ReJ, and in one gerbil: Meriones unguiculatus. Fecal samples and histological sections of the intestine taken on day 7 post-Cryptosporidium inoculation indicated that only the beige mouse (C57BL/6J-bgJ) harbored significant numbers of parasites compared to the other strains. The numbers of parasites harbored in these NK cell-deficient beige mice were, however, considerably lower than those seen in neonatal mice. Adult inbred mouse strains susceptible to Cryptosporidium infections are discussed.

A rat model is described in which animals develop respiratory cryptosporidiosis, a disease which is well documented in immunocompromised patients, especially those with AIDS. Our present lack of knowledge of the pathophysiology and immunology of Cryptosporidium parvum respiratory infections warrants the development of a laboratory animal model. Lewis rats immunosuppressed by subcutaneous injection of methylprednisolone acetate and inoculated intratracheally with 10(6) C. parvum oocysts developed a reproducible infection consisting of all known developmental stages in the epithelium lining airways from the trachea to the terminal bronchioles. Developmental stages were morphologically indistinguishable from those seen in gut epithelium. Infections were apparent at 4 days post-inoculation, and at 10-14 days post-inoculation, rats exhibited respiratory distress and severe weight loss and had enlarged, elastic lungs. Increased mucus production and exfoliative necrosis of the epithelium resulted in accumulation of large amounts of mucocellular exudate throughout the airways and patchy alveolitis involving alveoli emerging from respiratory bronchioles.

The following two species are described from Carduelis sinica (Greenfinch) from Italy. The oocysts of Isospora mcquistioni n. sp. were 26.0 x 22.6 (24.0-28.5 x 20.0-24.2) microns and ovoid with a smooth bilayered wall. Neither micropyle nor oocyst residuum were observed. One polar granule was found. Sporocysts were oval, 18.1 x 11.4 (16.0-19.8 x 11.0-12.0) microns, and with a symmetrical Stieda complex. The residuum was compact and spherical. Isospora bioccai n. sp. oocysts were spherical to subspherical and 24.0 x 23.6 (22.0-26.0 x 21.0-25.8) microns. The oocyst wall was smooth and bilayered. A micropyle and oocyst residuum were absent; 4 to 10 elongate polar granules were present. Sporocysts were 19.5 x 11.6 (18.0-20.0 x 10.0-12.4) microns, ellipsoidal, and with a symmetrical Stieda complex. The sporocyst residuum was diffuse and composed of a few granules.