Abstract
Toxoplasma gondii is a parasitic protozoan of worldwide distribution, able to infect all warm-blooded animals, but particularly sheep. Primary infection in pregnant sheep leads to millions of abortions and significant economic losses for the livestock industry. Moreover, infected animals constitute the main parasitic reservoir for humans. Therefore, the development of a One-health vaccine seems the best prevention strategy. Following earlier work, a vaccine constituted of total extract of Toxoplasma gondii proteins (TE) associated with maltodextrin nanoparticles (DGNP) was developed in rodents. In this study we evaluated the ability of this vaccine candidate to protect against latent and congenital toxoplasmosis in sheep. After two immunizations by either intranasal or intradermal route, DGNP/TE vaccine generated specific Th1-cellular immune response, mediated by APC-secretion of IFN-γ and IL-12. Secretion of IL-10 appeared to regulate this Th1 response for intradermally vaccinated sheep but was absent in intranasally-vaccinated animals. Finally, protection against latent toxoplasmosis and transplacental transmission were explored. Intranasal vaccination led to a marked decrease of brain cysts compared with the non-vaccinated group. This DGNP/TE vaccine administered intranasally conferred a high level of protection against latent toxoplasmosis and its transplacental transmission in sheep, highlighting the potential for development of such a vaccine for studies in other species.
Highlights
Toxoplasma gondii, an obligate intracellular parasitic protozoan, is the causative agent of toxoplasmosis
The presence of nanoparticles in relevant draining lymph nodes was investigated (Figure 2C). 1 h after intradermal neck inoculation, DGNP-DiR were only detected in retropharyngeal lymph node (3.65E + 07; data not shown) and as shown in Figure 2C no more signal was observed after 24 h
Toxoplasmosis is a zoonotic infection with global impact
Summary
Toxoplasma gondii, an obligate intracellular parasitic protozoan, is the causative agent of toxoplasmosis. This parasitic zoonosis is a widespread, infectious disease of warm-blooded vertebrates ( sheep), in which congenital infection may result in abortion or stillbirth. According to the Advisory Committee on the Microbiological Safety of Food, in a report published by the Food Standards Agency in 2012, human toxoplasmosis is the second major cause of death due to foodborne illness in United States – 24% vs 28% for Salmonella spp. [7] – and 30% of human infections are due to sheep meat consumption [8] According to the Advisory Committee on the Microbiological Safety of Food, in a report published by the Food Standards Agency in 2012, human toxoplasmosis is the second major cause of death due to foodborne illness in United States – 24% vs 28% for Salmonella spp. [7] – and 30% of human infections are due to sheep meat consumption [8]
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