الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Toxoplasma gondii (T.gondii) is an obligate intra-cellular protozoan parasite of the phylum Apicomplexa. More than 30 species of birds and 300 species of mammals, including humans are affected. Toxoplasma has a worldwide distribution. Human infection occurs after consumption of undercooked meat harbouring tissue cysts or from accidental ingestion of oocysts shed in cat’s faeces. Infection can also occur through transplacental transmission, accidentally in the laboratory or through blood transfusion.
The infection in most individuals is asymptomatic, whereas severe pathology and lethality due to toxoplasmosis are common findings in congenitally infected or immunodeficient individuals.
The great importance of T.gondii infection makes the development of a new control strategy of a great priority. Knowing that treatment of toxoplasmosis is difficult, with many toxic side effects of the drugs and possible reinfection, vaccination is considered the most potent and effective mean of fighting the disease through enhancement of the immune response. Different types of vaccines were tried with various degrees of success. Among the most commonly applied vaccines are; the inactivated or killed Toxoplasma vaccine, live attenuated vaccine, purified parasite antigen vaccine and DNA vaccines.
Adjuvants are usually required with killed vaccines to increase their efficacy and improve the response of the immune system. Previous studies confirmed that the use of adjuvants increases the efficacy of vaccines by up to 82%. One of most commonly used adjuvants in research is Freund’s incomplete adjuvant (FIA) due to its ability to stimulate innate immunity. It also induces expression of cytokines, predominantly tumour necrosis factor α (TNF-α) in regional lymph nodes and increases the permeability of the blood-brain barrier. Inspite of being generally the most effective, FIA causes severe inflammation. In recent years, various approaches have been tested as vaccine delivery systems. One of these is the development of nanoparticles prepared from biodegradable and biocompatible polymers. One of these polymers is chitosan.