Study On The Detection Of Toxoplasma Gondii From Soil By Hemi-nested PCR

Toxoplasma gondii is a widely distributed apicomplexan protozoal parasiteinfecting many species of warm-blooded animals, including humans. It can causetoxoplasmosis. This is one of the most prevalent parasitic infections that poses asevere threat to human health and the development of animal husbandry. People maybe infected with T. gondii mainly by ingestion of oocysts from soil that wascontaminated with the faeces of infected cats. Oocysts are shed into the environmentand spread via soil washing and penetration. They can contaminate soil and surfacewater. In order to get the information about oocyst distribution in soil, establishingdetection method of T. gondii from soil and collecting soil samples for detecting areimportant. It is also good for preventing the transmission of toxoplasmosis from soil.Microscopy and bioassays in mice are traditional detection methods that arebased on pathogeny of T. gondii. With the development of molecular biology, PCRwith strong specificity and high sensitivity is becoming a favored technique fordetection of T. gondii in soil. It can reduce the detection time and has been widelyused in the detection of T. gondii from environment. Specific primers were designedaccording to529bp sequence from T. gondii for the establishment of the hemi-nestedPCR. The detection was simpler than nested PCR and the reproducibility wasconfirmed well. Result of sensitivity showed the detection limit of the method was2oocysts in one gram of soil. There was no cross-reaction with Neospora caninum,Cryptosporidium bovis, Cryptosporidium baileyi, Babesia motasi, Babesia major,Babesia ovata, Babesia bigemina, Theileria sinensis, Babesia bovis, Theileriaannulata, Streptococcus bovis, Streptococcus suis, Enterococcus mundtii. Threepositive PCR products were subjected to DNA sequencing. The similarity betweenamplification sequences and the target gene were all more than97%.The soil samples from Lanzhou, pig farms in Beijing, and Qinghai province weredetected by the hemi-nested PCR. The results showed that the positive rates were15.63%,10.61%and9.17%respectively.The hemi-nested PCR is specific, sensitive, quick and suit for field investigations. The detection method provides technical support on getting information about oocystdistribution in soil, preventing and controlling the transmission of toxoplasmosis fromsoil.