Direct and photosensitized attenuation of Toxoplasma gondii tachyzoites

JUAN G. YAÑUK; M. LIS ALOMAR; M. MICAELA GONZALEZ; ANDRÉS M. ALONSO; SERGIO O. ANGEL; VERÓNICA M. CÓCERES; FRANCO M. CABRERIZO

Villa Carlos Paz

Congreso; XIII Encuentro Latinoamericano de Fotoquímica y Fotobiología (XIII ELAFOT); 2017

Toxoplasma gondii is a protozoan obligate intracellular parasite that can infect a wide range of animals including approximately one-third of the human population. Infection can result in severe clinical diseases.In addition, infection in domestic animals is a threat to public health from foodborne outbreaks and causes a great economic loss as it may lead to abortion, stillbirth and neonatal loss.Therefore, toxoplasmosis is of great medical and veterinary importance. Treatment of this disease is difficult since the available drugs have severe side effects and reactivation may occur at any time.Under the present scenario, therefore, developing an effective vaccine against T. gondii infection is the need of the hour.The vaccines based on live-attenuated parasites are more efficient than vaccines based on deadparasites, because the former ones emulates the natural infection. In this regard, γ, X-ray and UVC radiation have been used as attenuation sources of a remarkably wide range of parasite species. In every case, irradiated parasites induce protective immunity against subsequent challenge of experimental hosts.Regarding UVC irradiation, parasite?s attenuation may occur either due to direct absorption of the incident radiation by molecular targets or mediated by reactive oxygen species leading to a highly oxidant environment. Such an environment can certainly induce unspecific and uncontrollable damage on both morphological and functional aspects of the parasites. Thus, the type and/or extent of damage and, consequently, the immunogenicity, would depend on the UVC doses applied.Therefore, other attenuation sources such as UVA and visible radiation, via photosensitization, should be taken into account and further evaluated.In the present work, a systematic and comparative evaluation of the effect of three different types of radiation (UVC, UVA and visible) as attenuation sources of T. gondii tachyzoites has been carried out. In particular, we have evaluated the effect on morphological (structure and proteins stability, etc.), intracellular Reactive Oxygen Species (ROS) production and physiological functions (invasion and replication capability) of T. gondii tachyzoites.