Genetic approaches to studying virulence and pathogenesis in Toxoplasma gondii.
Toxoplasma gondii is a common protozoan parasite that causes disease in immunocompromised humans. Equipped with a wide array of experimental tools, T. gondii has rapidly developed as a model parasite for genetic studies. The population structure of T. gondii is highly clonal, consisting of three distinct lineages that differ dramatically in virulence. Acute virulence is probably mediated by the genetic differences that distinguish strain types. We have utilized a combination of genetic approaches to investigate the acute virulence of toxoplasmosis using the mouse model. These studies reveal the surprising finding that pathogenicity is due to the over-stimulation of normally protective immune responses. Classical genetic linkage mapping studies indicate that genes that mediate acute virulence are linked to chromosome VII in the parasite. To increase the resolution of genetic mapping studies, single-nucleotide polymorphisms are being developed based on an extensive database of expressed sequence tags (ESTs) from T. gondii. Separately, DNA microarray studies are being used to examine the expression of parasite and host genes during infection. Collectively, these approaches should improve current understanding of virulence and pathogenicity in toxoplasmosis.
Sibley
L David
LD
Department of Molecular Microbiology, Washington University School of Medicine, St Louis, MO 63110, USA. sibley@borcim.wustl.edu
Mordue
Dana G
DG
Su
Chunlei
C
Robben
Paul M
PM
Howe
Dan K
DK
D000483:Alleles; D000818:Animals; D001483:Base Sequence; D002874:Chromosome Mapping; D016207:Cytokines / Q000276:immunology; D020224:Expressed Sequence Tags; D020869:Gene Expression Profiling; D017125:Genes, Protozoan / Q000235:genetics; D051379:Mice; D020411:Oligonucleotide Array Sequence Analysis; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D018417:Th1 Cells / Q000276:immunology; D014122:Toxoplasma / Q000145:classification / Q000235:genetics* / Q000276:immunology / Q000472:pathogenicity*; D014123:Toxoplasmosis / Q000276:immunology / Q000469:parasitology*; D014774:Virulence / Q000235:genetics
D016207:Cytokines