A permanently high virulence was found in tachyzoites of T. gondii K24 after serial passage in mice (90 passages during 324 days). Virulence tests revealed that a single tachyzoite of the 50th passage represented LD100 for mice. Analysis of genotype of K24 isolate was done by PCR/RFLP with ROP1/Ddel, SAG1/Ddel, 850/Rsal and IGS/Rsal and by RFLP/DNA with TGR1E sequence and Pstl enzyme. K24 isola...

BACKGROUND Toxoplasma gondii is an obligate intracellular parasite that infects humans at high prevalence rates. The virulent RH strain of T. gondii is generally considered to have lost its cyst forming capacity. This study performed to obtain tissue cysts in mice infected with tachyzoites of RH strain treated with sulfadiazine (SDZ). It provides the opportunity to analyze the conversion of tac...

Toxoplasma gondii is one of the most successful protozoan parasites of warm-blooded animals. Stage-specific expression of its surface molecules is thought to be key to its ability to establish chronic infection in immunocompetent animals. The rapidly dividing tachyzoite stage displays a different subset of family of surface antigen 1 (SAG1)-related sequences (SRSs) from that displayed by the en...

Toxoplasma gondii mutants identified as defective in the establishment of chronic infection were screened to isolate those specifically impaired in their ability to replicate within activated macrophages. One of the identified mutants contains an insertion in the hypothetical gene TGME49_111670. Genetic complementation restores the ability of the mutant to replicate in immune cells and produce ...

Neospora caninum is an apicomplexan parasite that is closely related to Toxoplasma gondii and has been found to be associated with neurological disorders in dogs and congenital infections and abortions in cattle. We have identified two surface proteins of 29 and 35 kDa (designated Ncp29 and Ncp35, respectively) from N. caninum tachyzoites that are the predominant antigens recognized by antisera...

ELISA has been used for the diagnosis of toxoplasmosis, but it is being gradually replaced by a rapid diagnostic test (RDT). We compared and analyzed ELISA and RDT results using the sera collected during 4 consecutive years from residents of Gyodong-do (Island), Incheon-city, Korea. Sera from 921, 993, 940, and 838 adult residents were collected on a yearly basis (2010-2013). ELISA was performe...

Toxoplasma gondii is an obligate intracellular parasite infecting 25% of the world population and enormous number of animals. It can exist in two forms in intermediate hosts: the fast replicating tachyzoites responsible for acute infection and the slowly replicating bradyzoites responsible for life-long chronic infection. The interconversion between tachyzoites and bradyzoites plays critical ro...

We have evaluated the diagnostic utility of six antigenic regions of the Toxoplasma gondii MIC2, MIC3, M2AP, GRA3, GRA7, and SAG1 gene products, assembled in recombinant chimeric antigens by genetic engineering, in order to replace the soluble, whole-cell tachyzoite extract in serological assays. Serum samples from 100 adults with acquired T. gondii infection and from 30 infants born to mothers...