STUDY ON THE DISTRIBUTION OF RH STRAIN TOXOPLASMA GONDII IN EXPERIMENTAL INFECTED MICE / 中国人兽共患病学报

Aim In order to observe the pathological features and the dynamic distribution of RH strain T. gondii in main organs of infected mice, using indirect immunoenzymatic technique. To provide pathological diagonsising reference of toxoplasmosis and increase to understand the pathologensis of Toxoplasmosis. Methods Mice were infected intraperitoneally with 103 tachyzoites of T. gondii RH strain,and the parasites were detected using indirect immunoenzymatic technique in the liver, spleen, lungs and brain at 2,4,6 and 8 days postinfection. Results The liver was the first organ parasitized at D2, followed by spleen and lungs at D4, the brain at D8. At the early phase of infection, parasites were found on the edge of the liver and spleen. A few parasites were detected within the liver, spleen and lungs with time being. But parasites increased progressively and distributed well during the whole phase. The brain was the last organ to be parasitized. Parasites multiplicated rapidly so that the mice were seriously ill and died. Conclusions The indirect immunoenzymatic technique can demonstrate tachyzoites and Toaxoplasma antigen clearly in infected mice during acute stage. Many organs were infected such as liver, spleen,lungs and brain. The results suggest that the organs in the peritoneal cavity were infected directly by tachyzoites as IP infection, then the parasites disseminate through a blood way, and in the end, tachyzoites cross the blood-brain barries to reach the brain.

OBSERVATIONS ON THE GROWTH DYNAMICS OF 4 STRAINS OF TOXOPLASMA GONDII IN HELA CELLS / 中国寄生虫学与寄生虫病杂志

Growth dynamics of PP, CN and ZS2 strains of Toxoplasma gondii isolated in China was studied and compared with that of RH strain. HeLa cells were used in this work. It took only 2 min for the organisms of RH strain to infect the HeLa cells when con-tacting with the cells. By contrast, the CN strain requires 5 min, the ZS2 and PP strains, 10 min.Tcxoplasma began its multiplication after a lag time of about 6 h in the HeLa cells. The mean generation time of the 4 strains was assessed by calculating the number of the parasites in the parasitophorous vacuoles at different incubation times and by the linear regression equation. The results showed that the mean generation time was 5.2 h for RH strain, 5.98 h for CN strain, 6.78 h for ZS2 strain and 7.69 h for PP strain.Among the 3 strains of Toxoplasma gondii isolated in China, CN strain was similar to RH strain in their infectivity and proliferation.