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At least 19 recordsLinked to original sources
PubMed1979

[Malaria plasmodia in the mouse. Parasitization of mature and immature erythrocytes by Plasmodium berghei, Plasmodium yoelii and Plasmodium chabaudi (author's transl)].

Plasmodium berghei parasites (strain K173) in mice with developing immunity changed to a variant type with increased resistance against antibodies and enhanced invasion of mature erythrocytes; on passages in normal mice this variant type retransformed to the normal type (Kretschmar 1964). On detailed study, parasites of the variant type showed a markedly decreased predilection for polychromatophilic erythrocytes, leading to slowed multiplication during prepatency, increased invasion of mature erythrocytes and rapidly fatal course of the infection. Avoidance of parasitized immature erythrocytes remained unaltered in the variant type. In presence of antibodies many parasites invaded mature erythrocytes even in blood with high concentrations of immature erythrocytes. --Plasmodium yoelii (strain 17X) showed very high predilection for polychromatophilic erythrocytes, only slight lowering of immature erythrocyte concentration and low parasitization of mature erythrocytes. Parasites with altered preference for polychromatophilic erythrocytes were not observed in animals with parasitemia relapsing after spontaneous disappearance of the primary parasitemia or after injection of antiserum. It is suggested that in a variant of Plasmodium yoelii with high invasion of mature erythrocytes (Yoeli et al. 1975), the decisive virulence factor might be a lowered predilection for polychromatophilic erythrocytes. Avoidance of parasitized immature erythrocytes is less marked in Plasmodium yoelii than in Plasmodium berghei. In presence of antibodies more parasites invade mature erythrocytes. --Plasmodium chabaudi showed an appreciable preference for invasion of immature erythrocytes. Moreover, significantly more multiply parasitized mature and immature erythrocytes were found than would have been produced by random invasion of erythrocytes.

Animals↗
PubMed1983

The influence of cell type and culture medium on the in vitro cultivation of exoerythrocytic stages of Plasmodium berghei.

Plasmodium berghei sporozoites successfully entered and developed into exoerythrocytic schizonts in a variety of cell types cultured in vitro, but segmentation and release of merozoites was only observed in human embryonic lung cells. Exoerythrocytic development was generally not influenced by the culture medium, and NCTC-135 was used routinely. In vitro infectivity of P. berghei sporozoites was unaffected by the serum type used for isolation.

Animals↗
PubMed2006

Differential gene expression in the ookinete stage of the malaria parasite Plasmodium berghei.

Plasmodium, the malaria parasite, undergoes a complex developmental program in its mosquito vector. The ookinete is the parasite form which invades the mosquito midgut and is an important stage for genetic mixing. To identify genes expressed during ookinete development and mosquito midgut invasion, purified zygotes and ookinetes of the rodent parasite Plasmodium berghei were used to construct a suppression subtractive hybridization cDNA library, enriched in sequences expressed in the ookinete stage. In addition to four genes coding for previously described major ookinete-secreted proteins, we isolated ookinete-expressed sequences representing 18 predicted genes. Their gene products include proteins involved in signal transduction and regulatory processes. For six of these genes our analysis provides the first evidence for expression in the ookinete stage. A majority of the genes are not expressed in the zygote, the preceding developmental stage. Furthermore, four of the genes are also transcribed in sporozoites, and one of these in merozoites, suggesting that they code for proteins with a function common to Plasmodium invasive stages.

Animals↗
PubMed1999

The putative gene for the first enzyme of glutathione biosynthesis in Plasmodium berghei and Plasmodium falciparum.

The putative gene for gamma-glutamylcysteine synthetase, the rate-limiting enzyme in glutathione biosynthesis, has been characterized both in Plasmodium berghei and Plasmodium falciparum. Protein sequence comparison between these two species reveals large conserved regions sharing more than 80% similarity, separated by less conserved portions. When the comparison is extended to known gamma-glutamylcysteine synthetases from other eukaryotes, a number of high similarity blocks are observed which may help in identifying sequence essential for protein function.

Amino Acid Sequence↗
PubMed1988

A marker epitope of attenuated Plasmodium berghei.

Plasmodium berghei XAT is an irradiation-induced, permanent attenuated derivative from high-virulence P. berghei NK65. Monoclonal antibodies against XAT were developed. By immunofluorescence screening, one monoclonal antibody was identified that was reactive with XAT at the schizont stage but not with NK65 nor with any other stage of intra-erythrocytic development of either parasite. The monoclonal antibody precipitated a 240-kD molecule from metabolically labeled XAT antigens. This molecule was thought to be a marker epitope of the attenuated parasite.

Animals↗
PubMed2003

The dynamics of interactions between Plasmodium and the mosquito: a study of the infectivity of Plasmodium berghei and Plasmodium gallinaceum, and their transmission by Anopheles stephensi, Anopheles gambiae and Aedes aegypti.

Knowledge of parasite-mosquito interactions is essential to develop strategies that will reduce malaria transmission through the mosquito vector. In this study we investigated the development of two model malaria parasites, Plasmodium berghei and Plasmodium gallinaceum, in three mosquito species Anopheles stephensi, Anopheles gambiae and Aedes aegypti. New methods to study gamete production in vivo in combination with GFP-expressing ookinetes were employed to measure the large losses incurred by the parasites during infection of mosquitoes. All three mosquito species transmitted P. gallinaceum; P. berghei was only transmitted by Anopheles spp. Plasmodium gallinaceum initiates gamete production with high efficiency equally in the three mosquito species. By contrast P. berghei is less efficiently activated to produce gametes, and in Ae. aegypti microgamete formation is almost totally suppressed. In all parasite/vector combinations ookinete development is inefficient, 500-100,000-fold losses were encountered. Losses during ookinete-to-oocyst transformation range from fivefold in compatible vector parasite combinations (P. berghei/An. stephensi), through >100-fold in poor vector/parasite combinations (P. gallinaceum/An. stephensi), to complete blockade (>1,500 fold) in others (P. berghei/Ae. aegypti). Plasmodium berghei ookinetes survive poorly in the bloodmeal of Ae. aegypti and are unable to invade the midgut epithelium. Cultured mature ookinetes of P. berghei injected directly into the mosquito haemocoele produced salivary gland sporozoites in An. stephensi, but not in Ae. aegypti, suggesting that further species-specific incompatibilities occur downstream of the midgut epithelium in Ae. aegypti. These results show that in these parasite-mosquito combinations the susceptibility to malarial infection is regulated at multiple steps during the development of the parasites. Understanding these at the molecular level may contribute to the development of rational strategies to reduce the vector competence of malarial vectors.

Aedes↗
PubMed1997

The novel oxygenated chalcone, 2,4-dimethoxy-4'-butoxychalcone, exhibits potent activity against human malaria parasite Plasmodium falciparum in vitro and rodent parasites Plasmodium berghei and Plasmodium yoelii in vivo.

Previous studies have shown that licochalcone A, an oxygenated chalcone, exhibits antileishmanial and antimalarial activities. The present study was designed to examine the antimalarial activity of an analog of licochalcone A, 2,4-dimethoxy-4'-butoxychalcone (2,4mbc). 2,4mbc inhibited the in vitro growth of both a chloroquine-susceptible (3D7) and a chloroquine-resistant (Dd2) strain of Plasmodium falciparum in a [3H]hypoxanthine uptake assay. The in vivo activity of 2,4mbc was tested in mice infected with Plasmodium berghei or Plasmodium yoelii and in rats infected with P. berghei. 2,4mbc administered either orally, intraperitoneally, or subcutaneously for 5 days protected the mice from otherwise lethal infections of these parasites. 2,4mbc administered orally for 5 days reduced parasitemia in the rats infected with P. berghei. These results demonstrate that 2,4mbc exhibits potent antimalarial activity and might be developed into a new antimalarial drug.

Animals↗
PubMed2000

Characterization of the merozoite surface protein 4/5 gene of Plasmodium berghei and Plasmodium yoelii.

The genes encoding merozoite surface protein 4/5 (MSP4/5) from Plasmodium berghei and Plasmodium yoelii have been cloned and completely sequenced. Comparisons of the predicted protein sequences with those of Plasmodium chabaudi MSP4/5 and Plasmodium falciparum MSP4 and MSP5 show general structural similarities. All predicted proteins contain hydrophobic signal sequences, potential GPI attachment sequences and a single epidermal growth factor (EGF)-like domain at the C-terminus. The amino acid sequence of the EGF-like motif is highly conserved in rodent malaria species and also shows a considerable degree of similarity with the EGF-like domains found in the P. falciparum proteins. Both the P. yoelii and P. berghei genes show evidence of both spliced and unspliced mRNA at steady state. This phenomenon is similar to that seen for the P. chabaudi MSP4/5 gene, and is believed to be involved in regulation of protein expression. We describe here the construction of clones expressing full length recombinant protein. Antibodies directed against recombinant MSP4/5 proteins recognize a single polypeptide on parasite material and show crossreactivity between MSP4/5 from different murine malaria species, but do not crossreact with either MSP4 or MSP5 from P. falciparum. The various antisera show reactivity against reduction sensitive epitopes as well as reduction insensitive epitopes.

Amino Acid Motifs↗
PubMed1990

Possible roles of Ca2+ and cGMP as mediators of the exflagellation of Plasmodium berghei and Plasmodium falciparum.

The roles of Ca2+ and cyclic nucleotides as secondary, intracellular messengers for exflagellation of Plasmodium berghei and Plasmodium falciparum were investigated. Treatment with Ca2+ antagonists such as TMB-8 (an inhibitor of intracellular Ca2+ release) or W-7 (a calmodulin inhibitor) strongly inhibited exflagellation induced by alkaline medium at pH 8.0 whereas EGTA (a Ca2+ chelator) or nicardipine and nifedipine (Ca2+ channel inhibitors) had no effect. These results may indicate that mobilization of parasites' internal resources of Ca2+ is a prerequisite for exflagellation. Agents which increase cAMP levels did not induce exflagellation at the non-permissive pH of 7.3, and had no significant inhibitory effect at the permissive pH of 8.0. IBMX (cAMP/cGMP-phosphodiesterase inhibitor), however, enhanced exflagellation at pH 7.3, indicating the possibility that cGMP, but not cAMP, may be involved in the induction of exflagellation. Furthermore, cGMP or agents which increase cGMP levels such as nitroprusside (a potent activator of guanylate cyclase), enhanced exflagellation at pH 7.3, whereas N-methyl-hydroxylamine (guanylate cyclase inhibitor) inhibited the exflagellation at pH 8.0. From these results, it may be concluded that the induction of exflagellation requires both Ca2+ mobilization and an increase in cGMP levels.

Animals↗
PubMed1994

The role of free radicals and antioxidative enzymes in erythrocytes and liver cells in the course of Plasmodium berghei and Plasmodium vinckei infection of mice.

Blood schisontocidal test of D0 + D3 type revealed different characteristics of the Plasmodium berghei and Plasmodium vinckei infection. Both types of the rodent plasmodia kill the untreated mice. Chloroquine treatment alone does not prevent the death of the P. berghei infected animals and they died at a low level of parasitaemia. The animals cured with chloroquine plus MAP survive. The infection with P. vinckei produces a high level of parasitaemia and the chloroquine treatment alone prevents the death of mice. The difference in the pathogenic characteristics between P. berghei and P. vinckei is manifested in the results measuring the kinetics of the activity of antioxidative enzymes in the red blood and liver cells of the infected mice: lipid peroxidation (LPO), superoxide dismutases (SOD), glutathione peroxidase (GP), catalase (CAT) and reduced glutathione (GSH). The rapid increase of the LPO in the RBC in particular in the P. vinckei infected animals indicates the prevailing role of the membrane detoxification process. A continuous increase in the activity of enzymes of cytoplasmic origin, e.g. SOD and GP was also observed. A powerful increase in GSH distinguishes the erythrocytes of P. vinckei infected animals. Similar but not identical data characterize the enzyme activities of the liver cells of the plasmodia infected animals.

Animals↗
PubMed1997

Multiple antigen constructs (MACs): induction of sterile immunity against sporozoite stage of rodent malaria parasites, Plasmodium berghei and Plasmodium yoelii.

We prepared multiple antigen constructs (MACs) using circumsporozoite (CS) protein-based B-epitopes from Plasmodium berghei, (PPPPNPND)2 and Plasmodium yoelii, (QGPGAP)3QG, along with a P. berghei T-helper epitope KQIRDSITEEWS. Mice were immunized with individual MACs in oil-in-water or water-in-oil vehicles containing block copolymer (P1005) and detoxified RaLPS (RaLPS) as well as other adjuvants. Sporozoite challenge results demonstrated that MACs in adjuvant could induce antibodies capable of active and passive protection. Water-in-oil vaccines induced the highest level of protection in mice immunized with either P. berghei or P. yoelii MACs. In a study aimed at co-eliciting immunity against P. berghei and P. yoelii, three immunizations with MACs induced protective antibodies against P. berghei but not P. yoelii parasite challenge. Therefore, it can be concluded that individually MACs are capable of inducing strong and protective immune responses to either species of rodent malaria, and that protection can be passively transferred. When MAC formulations were used together as a combined vaccine, P. berghei MACs induced a strong protective antibody response while P. yoelii MACs induced a weaker nonprotective response.

Animals↗
PubMed1991

Role of host cellular response in differential susceptibility of nonimmunized BALB/c mice to Plasmodium berghei and Plasmodium yoelii sporozoites.

We found BALB/c mice to be on the order of 2,000 times more susceptible to Plasmodium yoelii than Plasmodium berghei sporozoites, as measured by the ability of these sporozoites to differentiate into microscopically detectable hepatic schizonts in the livers of immunologically naive mice. One of the factors that determine the relative insusceptibility of mice to P. berghei sporozoites is the innate cellular inflammatory response that the mice mount after injection with sporozoites. The cellular inflammatory response against P. berghei is initiated soon after sporozoite injection; by 24 h, substantial histopathological changes have developed within the liver. There is considerably less of a cellular inflammatory response against P. yoelii; significant histopathological changes within the liver are not observed until well after hepatic schizonts have begun to rupture at around 44 h postinjection of sporozoites. These differences in the cellular inflammatory response against two different, closely related species of sporozoites are of considerable interest. The data strongly suggest that the BALB/c-P. berghei sporozoite system is a relatively poor biological model for sporozoite immunization studies.

Animals↗
PubMed1992

Plasmodium berghei and Plasmodium chabaudi chabaudi: development of simple in vitro erythrocyte invasion assays.

Erythrocyte invasion assays are described for two species of rodent malaria, namely Plasmodium berghei and P.c. chabaudi. These invasion assays are simple, are carried out using a candle jar and allow a number of assays to be performed simultaneously. Our results demonstrate that both rodent malaria species show an in vitro preference for reticulocytes although the preference of P. c. chabaudi for these cells is not as marked as that of P. berghei. The details of our invasion assays and our results obtained are discussed.

Animals↗
PubMedDate not supplied

Common epitopes in the circumsporozoite proteins of Plasmodium berghei and Plasmodium gallinaceum identified by monoclonal antibodies to the P. gallinaceum circumsporozoite protein.

Monoclonal antibodies that react with the circumsporozoite protein of the avian malaria Plasmodium gallinaceum sporozoites also reacted with circumsporozoite protein of the rodent malaria Plasmodium berghei. Two types of reactivity were identified: 1) two monoclonal antibodies reacted with P. berghei sporozoite protein by enzyme-linked immunosorbent assay, Western blot and indirect immunofluorescence antibody, 2) six other monoclonal antibodies reacted with P. berghei sporozoites by ELISA and Western blot only. We studied whether these differences could be explained by reactivity in enzyme-linked immunosorbent assay with different P. berghei circumsporozoite peptides. Although all P. gallinaceum monoclonal antibodies reacted with the P. berghei repeats, the first group reacted with a conserved peptide sequence, N1, whereas the second group did not. These results suggest that circumsporozoite proteins from P. gallinaceum and P. berghei share common epitopes. The biological significance of our finding is not yet clear. Indeed, the cross-reactive monoclonal antibodies giving a positive indirect immunofluorescence antibody with the P. berghei sporozoites only caused a borderline effect on the living P. berghei parasites in vitro as measured by inhibition of sporozoite infectivity.

Amino Acid Sequence↗
PubMed1993

Expression of members of the heat-shock protein 70 family in the exoerythrocytic stages of Plasmodium berghei and Plasmodium falciparum.

Exoerythrocytic stages of Plasmodium berghei cultured in HepG2-A16 hepatoma cells and those of P. falciparum in human hepatocytes transplanted under the kidney capsule of CB-17/ICr scid/scid mice were used to evaluate expression of heat-shock-related stress proteins. Although undetectable in the sporozoites, the expression of proteins similar in sequence of a heat-shock protein of 70 kDa and a glucose-regulated protein of 78 kDa was markedly induced in the hepatic stages of malaria parasites. Expression of these proteins in the exoerythrocytic stages of the malaria parasite warrants a systematic evaluation of their potential role in eliciting cellular immune responses directed against infected hepatocytes.

Animals↗