Plasmodium Berghei Sporozoites (plasmodium + berghei_sporozoite)

Distribution by Scientific Domains


Selected Abstracts


The immune status of Kupffer cells profoundly influences their responses to infectious Plasmodium berghei sporozoites

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 8 2005
Nick Steers
Abstract Multi-factorial immune mechanisms underlie protection induced with radiation-attenuated Plasmodia sporozoites (,-spz). Spz pass through Kupffer cells (KC) before invading hepatocytes but the involvement of KC in protection is poorly understood. In this study we investigated whether ,-spz-immune KC respond to infectious spz in a manner that is distinct from the response of naive KC to infectious spz. KC were isolated from (1) naive, (2) spz-infected, (3) ,-spz-immune, and (4) ,-spz-immune-challenged C57BL/6 mice and examined for the expression of MHC class I and II, CD40 and CD80/CD86, IL-10 and IL-12 responses and antigen-presenting cell (APC) function. KC from ,-spz-immune-challenged mice up-regulated class I and costimulatory molecules and produced elevated IL-12p40, relative to naive KC. In contrast, KC from naive mice exposed to infectious spz down-modulated class I and IL-12p40 was undetectable. Accordingly, KC from spz-infected mice had reduced APC function, while KC from ,-spz-immune-challenged mice exhibited augmented APC activity. The nearly opposite responses are consistent with the fact that spz challenge of ,-spz-immune mice results in long-lasting sterile protection, while infection of naive mice always results in malaria. [source]


An early commitment to expression of a particular TCRV, chain on CD8+ T cells responding to attenuated Plasmodium berghei sporozoites is maintained following challenge with infectious sporozoites

PARASITE IMMUNOLOGY, Issue 9-10 2010
J. M. LUMSDEN
Summary Protection induced by irradiated Plasmodium berghei sporozoites (Pb,-spz) in mice is linked to CD8+ T cells specific for exo-erythrocytic-stage Ags, and intrahepatic memory CD8+ T cells are associated with protracted protection. However, the Ag specificity of the protective CD8+ T cells remains largely unknown. In this study, we characterized the TCR V, usage by intrahepatic CD8+ T cells during ,-spz immunization and after the challenge with infectious Pb sporozoites. The repertoire of naïve (TN) and central memory (TCM) CD8+ T cells was diverse and conserved between individual mice, and did not change with immunization. In contrast, preferential usage of one or more TCR V, subset was observed in effector memory (TEM) CD8+ T cells after immunization. The expanded TCR V, varied between individual mice but V,4, 6, 7, 8.3, 9 and 11 were the most frequently expressed. In addition, there was a correlation in the TCR V, usage by ,-spz-induced CD8+ TEM in the liver and blood of individual mice. The expansion pattern of blood CD8+ TEM did not change with challenge and remained the same for 8 weeks thereafter. These results demonstrate that immunization with ,-spz skews the TCR V, repertoire of CD8+ TEM, and commitment to a particular TCR V, expression is maintained long-term. [source]


Motility and infectivity of Plasmodium berghei sporozoites expressing avian Plasmodium gallinaceum circumsporozoite protein

CELLULAR MICROBIOLOGY, Issue 5 2005
Rita Tewari
Summary Avian and rodent malaria sporozoites selectively invade different vertebrate cell types, namely macrophages and hepatocytes, and develop in distantly related vector species. To investigate the role of the circumsporozoite (CS) protein in determining parasite survival in different vector species and vertebrate host cell types, we replaced the endogenous CS protein gene of the rodent malaria parasite Plasmodium berghei with that of the avian parasite P. gallinaceum and control rodent parasite P. yoelii. In anopheline mosquitoes, P. berghei parasites carrying P. gallinaceum and rodent parasite P. yoelii CS protein gene developed into oocysts and sporozoites. Plasmodium gallinaceum CS expressing transgenic sporozoites, although motile, failed to invade mosquito salivary glands and to infect mice, which suggests that motility alone is not sufficient for invasion. Notably, a percentage of infected Anopheles stephensi mosquitoes showed melanotic encapsulation of late stage oocysts. This was not observed in control infections or in A. gambiae infections. These findings shed new light on the role of the CS protein in the interaction of the parasite with both the mosquito vector and the rodent host. [source]


Fluorescent Plasmodium berghei sporozoites and pre-erythrocytic stages: a new tool to study mosquito and mammalian host interactions with malaria parasites

CELLULAR MICROBIOLOGY, Issue 6 2001
Ramya Natarajan
To track malaria parasites for biological studies within the mosquito and mammalian hosts, we constructed a stably transformed clonal line of Plasmodium berghei, PbFluspo, in which sporogonic and pre-erythrocytic liver-stage parasites are autonomously fluorescent. A cassette containing the structural gene for the FACS-adapted green fluorescent protein mutant 2 (GFPmut2), expressed from the 5, and 3, flanking sequences of the circumsporozoite (CS) protein gene, was integrated and expressed at the endogenous CS locus. Recombinant parasites, which bear a wild-type copy of CS, generated highly fluorescent oocysts and sporozoites that invaded mosquito salivary glands and were transmitted normally to rodent hosts. The parasites infected cultured hepatocytes in vitro, where they developed into fluorescent pre-erythrocytic forms. Mammalian cells infected by these parasites can be separated from non-infected cells by fluorescence activated cell sorter (FACS) analysis. These fluorescent insect and mammalian stages of P. berghei should be useful for phenotypic studies in their respective hosts, as well as for identification of new genes expressed in these parasite stages. [source]