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ATP-binding cassette (ABC) transporter proteins, one of the largest families of membrane transport proteins, participate in almost all biological processes and widely exist in living organisms. Microsporidia are intracellular parasites; they can reduce crop yields and pose a threat to human health. The ABC proteins are also present in microsporidia and play a critical role in their proliferation and energy transport. In this study, a novel ABC transporter protein of Nosema bombycis named NoboABCG1.3 was identified. The NoboABCG1.3 protein is comprised of 640 amino acids, which contain six transmembrane domains and one nucleotide-binding domain. After N. bombycis infection of cells or tissues, quantitative reverse transcription polymerase chain reaction analysis revealed a progressive elevation in the transcript levels of NoboABCG1.3. Downregulation of NoboABCG1.3 expression significantly inhibited N. bombycis proliferation. Subsequently, a transgenic cell line stably expressing an interfering fragment of NoboABCG1.3 was established, which exhibited extreme inhibition on the proliferation of N. bombycis. These findings indicate that NoboABCG1.3 plays a role in the proliferation of N. bombycis and holds promise as a target for developing N. bombycis-resistant silkworms., Competing Interests: Declarations. Ethics approval and consent to participate: This study received approval from the Laboratory Animals Ethics Review Committee of Southwest University (Chongqing, China), ensuring adherence to the Guidelines for Ethical Review of Experimental Animal Welfare (GBT35892-2018) throughout all animal experiments. Consent to participate: All authors confirm their participation in the study. Consent for publication: All authors consent to publication of the manuscript. Competing interests: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Reaginic and homocytotropic IgG antibodies in sera using passive cutaneous anaphylaxis (PCA) test and antigen from Litomosoides carinii were followed in Mastomys natalensis, infected with L. carinii, Dipetalonema viteae, Brugia malayi or B. pahangi. Groups of animals with infections of various ages so as to cover a total infection period of up to 300 to 420 days post-infection (p.i.), depending on the species of parasites, were bled at 1- to 3-week intervals over periods of 50-112 days. In addition, intradermal tests were performed on animals infected with L. carinii to detect immediate type hypersensitivity. Reaginic antibodies were usually first detected in the 3rd week after infection. Thereafter, a marked increase of PCA titres was observed in the 4th week p.i. leading to maximum titres 4 weeks after infection with D. viteae and B. pahangi and 6 weeks after B. malayi infection. Mean maximum titres were between 1:40 and 1:160. Following the peak response, titres decreased markedly until the beginning of patency in infections with D. viteae, B. malayi and B. pahangi whereas a constant course was observed at this time in animals infected with L. carinii. A further rise in PCA titres occurred in all infections around the beginning of patency, resulting in maximum reagin levels in L. carinii infections (mean titre 1:80) and moderate titres in the other infections. During early patency there was an inverse relationship between microfilaraemia density and levels of reaginic antibodies. However, in the phase of decreasing parasitaemia in L. carinii infected animals, microfilariae counts and PCA titres were directly correlated. Homocytotropic IgG antibodies showed relatively constant PCA titres of about 1:20 in L. carinii infected Mastomys throughout the observation period. In D. viteae infections they were demonstrated at 30 days p.i., reaching titres of about 1:40. B. malayi infected animals showed a maximum titre of 1:40 40 days p.i.. Thereafter, titres decreased continuously and homocytotropic IgG antibodies were absent at 110 days p.i.. High titres were observed at day 150 but thereafter sera were negative. B. pahangi infected animals showed moderate titres (1:5) 35 days p.i.. Thereafter, antibodies were found at low titres until 115 days p.i.. Intradermal reactions in L. carinii infected animals generally increased in size from 30-60 but decreased when microfilariae appeared in the blood.(ABSTRACT TRUNCATED AT 400 WORDS)

A novel microsporidial disease was documented in two ornamental fish species, black tetra Gymnocorymbus ternetzi Boulenger 1895 and cardinal tetra Paracheirodon axelrodi Schultz 1956. The non-xenoma-forming microsporidium occurred diffusely in most internal organs and the gill, thus referring to the condition as tetra disseminated microsporidiosis (TDM). The occurrence of TDM in black tetra was associated with chronic mortality in a domestic farmed population, while the case in cardinal tetra occurred in moribund fish while in quarantine at a public aquarium. Histology showed that coelomic visceral organs were frequently necrotic and severely disrupted by extensive infiltrates of macrophages. Infected macrophages were presumed responsible for the dissemination of spores throughout the body. Ultrastructural characteristics of the parasite developmental cycle included uninucleate meronts directly in the host cell cytoplasm. Sporonts were bi-nucleated as a result of karyokinesis and a parasite-produced sporophorous vesicle (SPV) became apparent at this stage. Cytokinesis resulted in two spores forming within each SPV. Spores were uniform in size, measuring about 3.9 ± 0.33 long by 2.0 ± 0.2 μm wide. Ultrastructure demonstrated two spore types, one with 9–12 polar filament coils and a double-layered exospore and a second type with 4–7 polar filament coils and a homogenously electron-dense exospore, with differences perhaps related to parasite transmission mechanisms. The 16S rDNA sequences showed closest identity to the genus Glugea (≈ 92%), though the developmental cycle, specifically being a non-xenoma-forming species and having two spores forming within a SPV, did not fit within the genus. Based on combined phylogenetic and ultrastructural characteristics, a new genus (Fusasporis) is proposed, with F. stethaprioni n. gen. n. sp. as the type species. [ABSTRACT FROM AUTHOR]

Encephalitozoon cuniculi is an obligate macrophage parasite of vertebrates that commonly infects rodents, monkeys, dogs, birds, and humans. In the present study, we aimed to assess the phagocytosis and intracellular survival of E. cuniculi spores using untreated and lipopolysaccharide (LPS)-activated J774A.1 murine macrophages and assess the macrophage viability. The experimental groups comprised untreated spores, spores killed by heat treatment at 90 °C, and spores killed by treatment with 10% formalin. LPS-activated macrophages significantly increased the phagocytosis of spores and reduced their intracellular growth after 24 and 48 h (P < 0.01); however, after 72 h, we observed an increase in spore replication but no detectable microbicidal activity. These results indicate that LPS activation enhanced E. cuniculi phagocytosis between 24 and 48 h of treatment, but the effect was lost after 72 h, enabling parasitic growth. This study contributes to the understanding of the phagocytosis and survival of E. cuniculi in murine macrophages. [ABSTRACT FROM AUTHOR]

A microsporidium was found in a Mediterranean cricket Gryllus bimaculatus from a pet market in the UK and a lab stock at the Moscow Zoo (originating from London Zoo). The spores were ovoid, uninucleate, 6.3 × 3.7 μm in size (unfixed), in packets by of 8, 16, or 32. The spores were easily discharged upon dessication or slight mechanical pressure. The polar tube was isofilar, with 15-16 coils arranged in 1-2 rows. The polaroplast was composed of thin lamellae and occupied about one third of the spore volume. The endospore was 200 nm thick, thinning over the anchoring disc. The exospore was thin, uniform, and with no ornamentation. Phylogenetics based upon small subunit ribosomal RNA (Genbank accession # MG663123) and RNA polymerase II largest subunit (# MG664544) genes placed the parasite at the base of the Trachipleistophora/Vavraia lineage. The RPB1 locus was polymorphic but similar genetic structure and identical clones were found in both isolates, confirming their common geographic origin. Due to in insufficient ultrastructural data and prominent divergence from described species, the parasite is provisionally placed to the collective taxon Microsporidium. [ABSTRACT FROM AUTHOR]

Nosema ceranae is a relatively new and widespread parasite of the western honeybee Apis mellifera that provokes a new form of nosemosis. In comparison to Nosema apis, which has been infecting the honeybee for much longer, N. ceranae seems to have co-evolved less with this host, causing a more virulent disease. Given that N. apis and N. ceranae are obligate intracellular microsporidian parasites, needing host energy to reproduce, energetic stress may be an important factor contributing to the increased virulence observed. Through feeding experiments on caged bees, we show that both mortality and sugar syrup consumption were higher in N. ceranae-infected bees than in N. apis-infected and control bees. The mortality and sugar syrup consumption are also higher in N. apis-infected bees than in controls, but are less than in N. ceranae-infected bees. With both microsporidia, mortality and sugar syrup consumption increased in function of the increasing spore counts administered for infection. The differences in energetic requirements between both Nosema spp. confirm that their metabolic patterns are not the same, which may depend critically on host-parasite interactions and, ultimately, on host pathology. The repercussions of this increased energetic stress may even explain the changes in host behavior due to starvation, lack of thermoregulatory capacity, or higher rates of trophallaxis, which might enhance transmission and bee death. [ABSTRACT FROM AUTHOR]

Spores of Trachipleistophora extenrec, originally isolated from the muscles of the Madagascan insectivore Hemicentetes semispinosus and maintained by serial passage in severe combined immunodeficiency (SCID) mice, were fed to larvae of the Egyptian cotton leafworm Spodoptera littoralis. Extensive infection of larval tissues ensued and caused larval and pupal mortality. The development of T. extenrec in the insect host, studied both by light and electron microscopy, followed generally the same life cycle as in the mammalian host. However, some differences in the fine structure of the parasite grown in both types of hosts were found. Spores isolated from the insect host caused infection of SCID mice when injected intramuscularly. Our results suggest that T. extenrec may be originally an insect microsporidian. This likelihood is corroborated by its structural similarity and phylogenetic relationship to two other microsporidia having insects either as unique hosts ( Vavraia culicis) or being able to infect both mammalian and insect host ( Trachipleistophora hominis). [ABSTRACT FROM AUTHOR]

Cytokine (interferon (IFN)-γ, interleukin (IL)-2, IL-4, IL-5, IL-10) gene transcription in response to filarial antigens was determined in peripheral blood mononuclear cells of Brugia malayi-infected Mastomys coucha in the course of untreated and chemotherapeutically abbreviated infections. Transcript levels in infected untreated animals suggest particular time courses for the various cytokines with ongoing parasite development and differing efficacies of female, male, microfilarial, and L3 antigens in inducing cytokine gene transcription. Gene transcription of both of Th1- and Th2- associated cytokines were initiated in the course of the infection in a manner that does not fit in a simple Th1–Th2 paradigm. IFN-γ and IL-4 gene transcripts prevailed during prepatency. In case of the other cytokine genes considered in the study, transcription in general peaked around beginning of patency. During the phase of increasing microfilaremia (approximately 120–180 days p. i.) cytokine gene transcription was generally decreased. Later on, when the parasitemia had leveled off, except IFN-γ, transcript levels often tended to increase. In chemotherapeutically treated animals, the outcome varied with the different efficacies of the drugs employed. The highly microfilaricidal cyclodepsipeptide BAY 44-4400 eliminated circulating microfilariae and partially sterilized adult worms without killing them. This kind of treatment hardly affected cytokine responses. In contrast, the therapy with Flubendazole®, a selectively macrofilaricidal benzimidazole, and particularly the application of CGP 20376, a highly efficient microfilaricidal and macrofilaricidal benzthiazole, resulted in enhanced transcription of the Th1- associated IFN-γ and IL-2 genes as well as of the Th2- associated IL-5 gene 2–3 months after treatment. IL-10 gene transcription seemed transiently increased after 1 month. There was no effect of any treatment on the IL-4 gene transcription. [ABSTRACT FROM AUTHOR]

Abstract??A new myxosporean parasite,Myxobolus lubatin. sp., was described from the wall of the intestine of haffara seabreamRhabdosargus haffara(Forsskal 1775), Red Sea, Egypt. Macroscopic plasmodia of about 300??m diameter were located in the circular muscle layer of the intestine. The spores were ovoid and sometimes ellipsoid and measured 9.8???7.2??m. The shell wall of the spore was thickened at the posterior end and marked with 5?7 sutural markings. Polar capsules were equal and pyriform with three polar filament turns situated in the posterior half of the polar capsule. Polar capsules measured 4.2???1.6??m. Histological evaluation of the infection revealed a slight distention of the intestinal layer of muscularis. Ultrastructure of the plasmodial wall and sporogenesis of the present species followed the usual pattern valid for most studied myxosporean species. [ABSTRACT FROM AUTHOR]

Abstract??The intracellular apicomplexan parasiteToxoplasma gondiiis able to survive and persist in immunocompetent intermediate hosts for the host?s life span. This is despite the induction of a vigorous humoral and?more importantly?cell-mediated immune response during infection. In order to establish and maintain such chronic infections, however,T. gondiihas evolved multiple strategies to avoid or to interfere with potentially efficient anti-parasitic immune responses of the host. Such immune evasion includes (1) indirect mechanisms by altering the expression and secretion of immunomodulatory cytokines or by altering the viability of immune cells and (2) direct mechanisms by establishing a lifestyle within a suitable intracellular niche and by interference with intracellular signaling cascades, thereby abolishing a number of antimicrobial effector mechanisms of the host. Despite the parasite?s ability to interfere successfully with the host?s efforts to eradicate the infection, the immune response is, however, not completely abrogated but is rather partially diminished after infection.T. gondiithus keeps a delicate balance between induction and suppression of the host?s immune response in order to guarantee the survival of the host as a safe harbor for parasite development and to allow its transmission to the definitive host. [ABSTRACT FROM AUTHOR]

Mastomys coucha and jirds infected with Acanthocheilonema viteae, a filarial species free of endosymbiontic bacteria of the genus Wolbachia, suffer lethal side effects after effective microfilaricidal therapy with diethylcarbamazine and levamisole, whereas, M. coucha infected with the Wolbachia-infested species Brugia malayi or Litomosoides carinii tolerate corresponding treatment. Mortality in A. viteae infected, treated animals varied with microfilariae density in the blood. It was up to 100% in highly microfilaraemic M. coucha and jirds, but low or absent in animals with low microfilariae counts. Deaths occurred in most cases 5–24 h after treatment. Characteristic symptoms in animals, which died subsequently were a rapid drop in body temperature by 4–7°C, an increase in hematokrit values by up to 10% and a moderate blood acidosis. Lethal effects in A. viteae infections did not depend on a particular status of hypersensitivity of the animals since desensitization procedures, which protected infected M. coucha against an otherwise lethal intravenous challenge with A. viteae homogenate did not protect against adverse reactions to a subsequent microfilaricidal treatment. The animals were protected from treatment induced death by injection of N-LMMA. Thus the final morbific agent seems NO. The data show that adverse effects after effective microfilaricidal therapy may be caused by microfilariae derived components different from Wolbachia-released LPS. [ABSTRACT FROM AUTHOR]

Toxoplasma gondii is an intracellular, obligate protozoan parasite that actively invades host cells. Phospholipases A2 (PLA2) are widely distributed enzymes that exist in many isoforms [secretory (sPLA2), cytosolic (cPLA2)] in monocytic and other human cells (pancreatic, kidney, etc) and also in parasites. We examined the effects of inhibitors of sPLA2 type II and cPLA2 on the invasion of human monocytic cells (THP1) by T. gondii (RH strain). We also measured sPLA2 type II and cPLA2 enzyme activities and their modulation by interferon γ (IFN γ) in extracts of host cells and parasite. Inhibition of both parasite and THP1 sPLA2 type II, and of parasite cPLA2 reduced the number of infected cells. Enzyme assays and immunoblot analyses demonstrated T. gondii sPLA2 type II and cPLA2 activities and indicated that T. gondii increased the activity of THP1 sPLA2 type II. Incubation with IFN γ (1,000 units/ml) for 20 h reduced the activities of sPLA2 and cPLA2 in infected and non-infected cells. Thus, IFN γ blocks the activities of both THP1 and parasite sPLA2 and cPLA2 in membrane fractions, resulting in protection against active invasion by T. gondii. [ABSTRACT FROM AUTHOR]

The viability of the fish-infecting microsporidian Loma salmonae Morrison and Sprague, 1981 was determined under laboratory conditions by polar filament extrusion and infectivity to chinook salmon ( Oncorhynchus tshawytscha). Extrusion rates of isolated spores decreased from 51.0% to 0.0% by 100 days after storage in fresh or sea water at 4 °C. Spores stored up to 95 days in either solution infected 80.0–100.0% of exposed chinook, although no spores infected fish at 100 days in one trial. Viability in Earl's balanced salt solution was tested up to 50 days, with 23.7% of spores extruding filaments and 80.0% of exposed chinook becoming infected. Spores frozen to −20 °C or −70 °C were unable to infect fish. [ABSTRACT FROM AUTHOR]

Loading of Eimeria bovis-infected Vero cells with membrane-permeant acetoxymethyl esters (AM-esters) of ion-sensitive dyes provided us with a noninvasive method for investigation of the permeability of the parasitophorous vacuole membrane (PVM) and simultaneous measurement of Ca2+ and H+ concentrations in different compartments of the infected cells. The distribution patterns of the cleaved membrane-impermeant dyes argue against the existence of nonselective pores in the PVM. There is also no indication of a parasitophorous duct connecting the vacuolar space with extracellular media. The pH inside the parasitophorous vacuole (PV) was lower than that in the cytoplasm of the host cell or the parasite, whereas the [Ca2+] in these compartments did not differ significantly. In HT29 cells infected with E. separata for 24 h the Ca2+ response to extracellular adenosine triphosphate (ATP) was significantly reduced, indicating influences on the host cell's intracellular signaling. [ABSTRACT FROM AUTHOR]

The levels of parasite-specific IgG1 and IgG2 antibodies and mitogen-induced and parasite-specific proliferative T-cell responses were determined in Litomosoides sigmodontis-infected Mastomys coucha throughout an observation period of 400 days post infection (p.i.). These were compared with the respective reactions in animals that had been immunized with intrauterine stages/microfilariae of the parasite and in animals that had been challenged after immunization as determined at up to 60 days after challenge. IgG1 antibodies to adult antigen developed early and reached a plateau at 120 days p.i., whereas IgG2 antibodies were not found before day 60 p.i., increased with rising parasitemia, reached a plateau at 200 days p.i., and, in some animals, even became the predominant IgG subclass. Proliferative responses of spleen lymphocytes to concanavalin A (Con A) and lipopolysaccharides (LPS), but not Con-A-induced interleukin 2 (IL-2) production, were found to be suppressed in infected animals during patency as compared with uninfected controls. Spleen cells of infected animals showed a weak proliferative reaction to male antigen but were unresponsive to female and microfilarial antigen during prepatency and early patency. Subsequently, when microfilaremia decreased (200 days p.i.), continuously increasing responses to all antigens were observed. Immunized M. coucha developed specific IgG1 and IgG2 antibodies, and their spleen cells showed strong proliferative responses to the three L. sigmodontis antigens. Challenge infections down-regulated the proliferative responses of spleen cells to filarial antigens as early as during the prepatent phase of the challenge infection but supported existing IgG1 and IgG2 responses. [ABSTRACT FROM AUTHOR]

The invasion of Toxoplasma gondii tachyzoites and bradyzoites was followed in bovine kidney cells via electron microscopy. The process of invasion differed between bradyzoites and tachyzoites. In the early stages of entry there was evidence of localised formation of membrane projections in the host cell adjacent to the parasite. Parasite reorientation and rhoptry release appeared to be necessary for invasion; however, the tight junction could not be clearly discerned and there was no evidence of constriction or of any membrane shedding from the parasite. The resulting parasitophorous vacuole was smaller than the tachyzoite vacuole and parasites were frequently found to lie immediately under the host cell membrane. The vacuole was rapidly adapted by the release and formation of an intra-phagosomal membrane network, while the parasitophorous vacuole formed a relationship with host-cell endoplasmic reticulum. [ABSTRACT FROM AUTHOR]

As a member of the phylum Microspora, Nosema algerae is a small obligate intracellular parasite. Its free invasive stage is a spore with a characteristic cellular organization, including an apically anchored polar tube that serves as a tool for the transmission of genetic material into the host cell. By detailed electron micrographic documentation of the spore ultrastructure we present the aspects related to the biologic process of spore extrusion. Our ultrastructure findings confirm that the extrusion process of microsporidian spores is based on extreme changes in their organization. This study is the first complete ultrastructural documentation of N. algerae concerning the extrusion process, which can be subdivided into different stages: the breakdown of the microsporidian cellular compartmentation; the filling of a preformed polar tube with modified sporoplasm; the uncoiling of the polar tube, which in this stage has reached its final length; and, finally, its extrusion and screw-like movement. [ABSTRACT FROM AUTHOR]

Immunoperoxidase localisation of antigen at the electron microscope level confirms that parasite surface proteins, in association with membrane, are shed from the surface of the zoite on invasion, while varying amounts are also internalised. SAG 1 is stable on intracellular zoites for up to 48h, although new protein is also synthesised. SAG1 is present on the surface of daughter zoites and is found throughout the infected cell in distinct vacuoles; these vacuoles represent either direct extensions of the parasitophorous vacuole or true export of parasite surface material. [ABSTRACT FROM AUTHOR]

Effects of levamisole, orally administered at 1, 3, 5 or 7 successive daily doses of 30 mg/kg, on the number of first-stage larvae of Angiostrongylus cantonensis released in the faeces of treated rats were examined. First-stage larval counts (larvae per gram of faeces per female worm recovered, LPG/female) were conspicuously reduced 1 day after administration in all treated groups. In the group treated with a single dose, the larval counts increased 2 days after administration, but no larvae could be detected in the other treated groups. Histological observations of lung tissues of the host showed the degenerative changes in the reproductive system of the worms. These results suggest that levamisole affects the larval output of A. cantonensis through a direct paralyzing action and an indirect mode of action including inhibition in energy metabolism. [ABSTRACT FROM AUTHOR]

Human fibroblast cell cultures inoculated with microsporidia-infected corneal scrapings from an AIDS patient were fixed in situ and examined by scanning and transmission electron microscopy. The parasite grew prolifically and all developmental stages were observed. Meronts underwent binary fission and the daughter cells transformed into clongate, chain-like sporonts that eventually separated into sporoblasts. The formation of components of the mature spores is described. The parasite, a species of Encephalitozoon, underwent development both in the cytoplasm and within a parasitophorous vacuole, distinguishing it from the morphologically similar species E. cuniculi and E. hellem, both of which have been described from lesions in the human eye and have been reported to develop exclusively within a parasitophorous vacuole. [ABSTRACT FROM AUTHOR]

Tachyzoites of Toxoplasma gondii have been shown to exocytose the contents of dense granules into the parasitophorous vacuole after host cell invasion. A monoclonal antibody specific for a 27-kDa protein was used to locate the dense granules by immunoelectron microscopy. The same antibody also reacted with the tubular network found in the parasitophorous vacuole, which confirmed that the dense granules were exocytosed by tachyzoites. [ABSTRACT FROM AUTHOR]

A Nosema-like microsporidian with transovarian passage was found in most organs, including muscle and nervous tissue, of newly hatched and adult wasps. The mitotic apparatus of the dikaryotic meronts includes spindle-pole bodies with intra- and extranuclear components and small kinetochores with single microtubules. Cytokinesis in stages with four nuclei involves budding. The spore wall reacts with Calcofluor White, a fluorochrome specific for β-1,4 glycosidic linkages such as those found in chitin. [ABSTRACT FROM AUTHOR]

The multivalvulid myxosporean Kudoa lunata Lom, Dyková and Lhotáková, 1983 forms large polysporic trophozoites within the myocytes of scaldfish, Arnoglossus imperialis and A. laterna. The spores arise by the division of generative cells that produce a number of sporogonic cells necessary to complete a sporoblast. The development of some of the sporogonic cells can take place in isolation from other sporoblast cells, as shown by aberrant cases of polar capsule formation. Pansporoblast formation does not exist in Kudoa, at variance with large polysporic trophozoites of other myxosporean genera. The genus Kudoa also includes species with small trophozoites producing just one or two spores without pansporoblasts, as in Sphaerospora. Perhaps this type of sporogenesis was preserved in the species of Kudoa that have large trophozoites. Kudoa spores have a unique type of sporoplasm, comprising an outer cell enveloping an inner one; these differ in their contents of ribosomes and glycogen granules. This type of sporoplasm is reminiscent of the basic unit of all types of myxosporean development, i.e., the primary (vegetative) cell enclosing an inner (generative) cell. The canals for filament discharge extend through the apical spore projections and are of a length unmatched in other myxosporea. [ABSTRACT FROM AUTHOR]

In rats infected with different worm burdens of Angiostrongylus cantonensis, the loss of body weight was proportional to the increasing dose of infection. Body weight was correlated inversely with female worm burden ( r=−0.669), the sum of mean numbers of larvae per gram of faeces (LPG) ( r=−0.527) and lung weight ( r=−0.761). Lung weight was positively correlated with female worm burden ( r=0.785) and the sum of mean numbers of LPG ( r=0.685). On the other hand, in rats infected with larvae developed from gamma-irradiated first-stage larvae (Experiment B) or infected rats treated with the drug ivermectin (Experiment C), body weight was inversely correlated with the sum of mean numbers of LPG ( r= −0.798, Experiment B; r=−0.670, Experiment C) and lung weigth ( r=−0.862, Experiment B; r= −0.812, Experiment C), but not with female worm burden. Furthermore, lung weight was positively correlated with the sum of mean numbers of LPG ( r=−0.783, Experiment B; r=0.899, Experiment C), but not with the female worm burden. From these results, it is concluded that in the later pulmonary phase of infection in rats the pathogenic effects may be closely related to the increasing number of first-stage larvae produced by female worms. [ABSTRACT FROM AUTHOR]

Catalase and glutathione peroxidase (Gpx), two enzymes destroying hydrogen peroxide, were reported in two Babesia species: B. divergens cultivated in vitro and B.hylomysci obtained in vivo. On the use of specific substrate and inhibitor, we confirmed that the Gpx activity detected was selenium-dependent. Moreover, the two Babesia species contain glutamate dehydrogenase activity. This enzyme is capable of providing to the cell the reduced nicotinamide adenine dinucleotide phosphate (NADPH) necessary for regeneration of the reduced glutathione. Gpx activity is weaker in B. divergens than in B. hylomysci and seems to be compensated by higher levels of catalase activity. Such a balance between the two enzymes may depend on the selenium concentration available for the parasite. [ABSTRACT FROM AUTHOR]