Faculty Opinions recommendation of Critical role of a K+ channel in Plasmodium berghei transmission revealed by targeted gene disruption.

ABSTRACT Infection with Plasmodium berghei is lethal to mice, causing high levels of parasitemia, severe anemia, and death. However, when mice are treated with antimalarial drugs during acute infection, they have enhanced immunity to subsequent infections. With this infection and cure model of immunity, we systematically examined the basis of adaptive immunity to infection using immunodeficient mice. In order to induce adaptive immunity, mice were infected with blood-stage parasites. When the mice developed 2 to 3% parasitemia, they were treated with chloroquine to cure the infection. These convalescent mice were then challenged with homologous blood-stage parasites. Immunized wild-type mice were able to control the level of infection. In contrast, mice lacking mature B cells and T cells were unable to control a challenge infection, indicating the critical role of lymphocytes in immunity to P. berghei. Furthermore, mice lacking secreted antibody were unable to control the level of parasitemia following a challenge infection. Our results indicate that secreted antibody is a requirement for immunity to P. berghei.

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Generation and Analysis of Mice Lacking the Chemokine Fractalkine

Molecular and Cellular Biology ◽

10.1128/mcb.21.9.3159-3165.2001 ◽

2001 ◽

Vol 21 (9) ◽

pp. 3159-3165 ◽

Cited By ~ 102

Author(s):

Donald N. Cook ◽

Shu-Cheng Chen ◽

Lee M. Sullivan ◽

Denise J. Manfra ◽

Maria T. Wiekowski ◽

...

Keyword(s):

Gene Disruption ◽

Surface Marker ◽

Wild Type ◽

Blood Leukocytes ◽

Targeted Gene Disruption ◽

Behavioral Abnormalities ◽

Inflammatory Stimuli ◽

Membrane Bound ◽

Deficient Mice

ABSTRACT Fractalkine (CX3CL1) is the first described chemokine that can exist either as a soluble protein or as a membrane-bound molecule. Both forms of fractalkine can mediate adhesion of cells expressing its receptor, CX3CR1. This activity, together with its expression on endothelial cells, suggests that fractalkine might mediate adhesion of leukocytes to the endothelium during inflammation. Fractalkine is also highly expressed in neurons, and its receptor, CX3CR1, is expressed on glial cells. To determine the biologic role of fractalkine, we used targeted gene disruption to generate fractalkine-deficient mice. These mice did not exhibit overt behavioral abnormalities, and histologic analysis of their brains did not reveal any gross changes compared to wild-type mice. In addition, these mice had normal hematologic profiles except for a decrease in the number of blood leukocytes expressing the cell surface marker F4/80. The cellular composition of their lymph nodes did not differ significantly from that of wild-type mice. Similarly, the responses offractalkine −/− mice to a variety of inflammatory stimuli were indistinguishable from those of wild-type mice.

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Targeted Gene Disruption Reveals an Adhesin Indispensable for Pathogenicity of Blastomyces dermatitidis

Journal of Experimental Medicine ◽

10.1084/jem.189.8.1207 ◽

1999 ◽

Vol 189 (8) ◽

pp. 1207-1216 ◽

Cited By ~ 118

Author(s):

T. Tristan Brandhorst ◽

Marcel Wüthrich ◽

Thomas Warner ◽

Bruce Klein

Keyword(s):

Gene Transfer ◽

Gene Disruption ◽

Reverse Genetics ◽

Fungal Infections ◽

Blastomyces Dermatitidis ◽

Dimorphic Fungi ◽

Targeted Gene Disruption ◽

Allelic Replacement ◽

Impaired Binding

Systemic fungal infections are becoming more common and difficult to treat, yet the pathogenesis of these infectious diseases remains poorly understood. In many cases, pathogenicity can be attributed to the ability of the fungi to adhere to target tissues, but the lack of tractable genetic systems has limited progress in understanding and interfering with the offending fungal products. In Blastomyces dermatitidis, the agent of blastomycosis, a respiratory and disseminated mycosis of people and animals worldwide, expression of the putative adhesin encoded by the WI-1 gene was investigated as a possible virulence factor. DNA-mediated gene transfer was used to disrupt the WI-1 locus by allelic replacement, resulting in impaired binding and entry of yeasts into macrophages, loss of adherence to lung tissue, and abolishment of virulence in mice; each of these properties was fully restored after reconstitution of WI-1 by means of gene transfer. These findings establish the pivotal role of WI-1 in adherence and virulence of B. dermatitidis yeasts. To our knowledge, they offer the first example of a genetically proven virulence determinant among systemic dimorphic fungi, and underscore the value of reverse genetics for studies of pathogenesis in these organisms.

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