A new atypical highly mouse virulent Toxoplasma gondii genotype isolated from a wild black bear in Alaska.
Most strains of Toxoplasma gondii isolated in North America and Europe are grouped into 3 (Types I, II, III) genotypes and are considered clonal. Recent evidence suggests that illness due to toxoplasmosis in immunocompetent persons may be related to infection with an atypical genotype; these strains are mouse virulent. In the present study, a new mouse-virulent atypical T. gondii genotype was isolated from an asymptomatic black bear ( Ursus americanus ) from Alaska. The bear had a titer of 1ratio1,600 using the modified agglutination test for T. gondii . Swiss Webster out-bred mice inoculated with bear heart homogenate died of acute toxoplasmosis, 12 days post-inoculation (PI). Cats fed tissues from chronically infected animals (day 30 PI) shed oocysts, but only 1 of 3 cats fed acutely infected mice (12, 16, 18 days PI) shed oocysts. The isolate (designated TgBbUS1) was mouse virulent; mice inoculated with 1 oocyst or 1 tachyzoite died of acute toxoplasmosis. The restricted fragment length polymorphism using 10 markers revealed that the strain possessed an atypical genotype: type I allele at loci SAG1, (5'-3')SAG2, SAG3, c22-8, c29-2, L358, and Apico; type II allele at locus alt.SAG2; and type III allele at loci BTUB, GRA6, and PK1. DNA sequencing at intron loci EF1, HP2, and UPRT1 revealed that the TgBbUS1 is a divergent T. gondii strain. These results indicate that mouse-virulent atypical T. gondii genotypes are also circulating in wildlife in North America.
Dubey
J P
JP
Animal Parasitic Diseases Laboratory, Animal and Natural Resources Institute, Beltsville Agricultural Research Center, United States Department of Agriculture, Beltsville, MD 20705-2350, USA. jitender.dubey@ars.usda.gov
Rajendran
C
C
Ferreira
L R
LR
Kwok
O C H
OC
Sinnett
D
D
Majumdar
D
D
Su
C
C
D000372:Agglutination Tests / Q000662:veterinary; D000413:Alaska; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D001681:Biological Assay / Q000662:veterinary; D001921:Brain / Q000469:parasitology; D002415:Cats; D002522:Chlorocebus aethiops; D005260:Female; D005838:Genotype; D008168:Lung / Q000469:parasitology; D051379:Mice; D018345:Mice, Knockout; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D014122:Toxoplasma / Q000145:classification* / Q000235:genetics / Q000276:immunology / Q000472:pathogenicity*; D014124:Toxoplasmosis, Animal / Q000469:parasitology*; D001503:Ursidae / Q000469:parasitology*; D014774:Virulence
D000913:Antibodies, Protozoan