Cloning of Major Surface Antigen (SAG1) Gene of Toxoplasma gondii Tachyzoites

Toxoplasma gondii is an obligate intracellular protozoon parasite of all the warm blooded animals including birds and humans. It completes a sexual part of its life cycle in the intestinal epithelial cell of the Felidae (definitive host) and an asexual part in warm blooded (intermediate host). Human is an accidental host who contracts infection through handling cat litter and gardening, ingestion of water and vegetation contaminated with cat faeces by consumption of raw or undercooked meat containing tissue cyst and transplacentally from mother to children (Miller et al., 1972). Toxoplasmosis occurs in two forms: acute infection and chronic infection. In acute infection tachyzoites multiply rapidly, reaches different organs/tissues of body via blood and lymph and convert to a slow multiplying stage bradyzoite inside tissue cyst. Toxoplasmosis is mostly detected by serological assays employing whole cell antigen in both animals and human. Early accurate diagnosis of Toxoplasma infection in animals and human is very important to avoid the untoward consequences from the infection. Among serological tests, ELISA has a specific value and availability of stage specific parasite International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 6 Number 7 (2017) pp. 161-167 Journal homepage: http://www.ijcmas.com