A comprehensive review of toxoplasma gondii biology and host-cell interaction: Challenges for a plant-based vaccine

Abstract

Toxoplasmosis is a worldwide-distributed infection caused by Toxoplasma gondii, which causes a wide range of clinical syndromes in humans, mammals and birds. T. gondii is considered a parasite of veterinary and medical importance, because it may cause abortion or congenital disease in its intermediate hosts. Despite the economic losses associated with T. gondii infection in farm animals and the socio-economic impact caused by this zoonotic disease in the human population, there is no effective treatment available for humans or animals able to eliminate the parasite from the host once the chronic infection has been established. The only commercial vaccine is the S48 strain of attenuated tachyzoites for use in sheep. However, this vaccine causes side effects, has a short life time and induces a short-term immunity. So far, no acellular vaccine against toxoplasmosis has been commercialized. In fact, future challenges include the development of an effective vaccine to prevent toxoplasmosis. Most parasitologists and vaccinologists agree that future efforts should be concentrated on developing multi-antigen vaccines and more efficient delivery systems able to express heterologous proteins abundantly as well as on searching for immunization schedules and adequate adjuvants to enhance the protective responses. To achieve this, platforms for the production of acellular vaccines based on the use of plants can have an important role.