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Dogs are the main source of human cystic echinococcosis. An oral vaccine would be an important contribution to control programs in endemic countries. We conducted two parallel experimental trials in Morocco and Tunisia of a new oral vaccine candidate against Echinococcus granulosus in 28 dogs. The vaccine was prepared using two recombinant proteins from adult worms, a tropomyosin (EgTrp) and a fibrillar protein similar to paramyosin (EgA31), cloned and expressed in a live attenuated strain of Salmonella enterica serovar typhimurium.In each country, five dogs were vaccinated with the associated EgA31 and EgTrp; three dogs received only the vector Salmonella; and six dogs were used as different controls. The vaccinated dogs received two oral doses of the vaccine 21 d apart, and were challenged 20 d later with 75,000 living protoscoleces. The controls were challenged under the same conditions. All dogs were sacrificed 26–29 d postchallenge, before the appearance of eggs, for safety reasons.We studied the histological responses to both the vaccine and control at the level of the duodenum, the natural localization of the cestode. Here we show a significant decrease of parasite burden in vaccinated dogs (70% to 80%) and a slower development rate in all remaining worms. The Salmonella vaccine EgA31-EgTrp demonstrated a high efficacy against E. granulosus promoting its potential role in reducing transmission to humans and animals.

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Abstract. The effect of artesunate and its metabolite dihydroartemisinin against the cerebral cysts of Toxoplasma gondii was studied. In vitro experiments were performed with the THP-1 cell line and showed an inhibition of parasite growth of approximately 70% with 0.1-0.5 g/ml of dihydroartemisinin for 96 hr. However, with artesunate, dihydroartemisinin, or a combination (50:50) of them, the number of tachyzoites decreased approximately 40-50% and they appeared motionless. Fifty-eight to 72 hr after washing of the tachyzoites and THP-1 cells in culture, parasitized cells reappeared. In vivo, the 50:50 artesunate-dihydroartemisinin combination produced a decrease in cerebral cysts of approximately 40% after only 5 days of treatment. However, transplantations into naïve mice using brains of treated mice gave positive results.Artemisinin, a peroxide-containing sesquiterpene lactone isolated from the herb Artemisia annua, has been found to possess potent antimalarial activity and low toxicity both in animals and humans. 1,2 Artesunate (a water soluble half-ester succinate derivative) and artemether (a methyl ether derivative) are the only 2 derivatives of artemisinin that have been licensed in Thailand for treatment of Plasmodium falciparum malaria since 1990.Because of their low solubility in either water or oil 1 and the short plasma half-life of artemisinin, artesunate and artemether have been studied, in particular, sodium artesunate. 3 All artemisinin derivatives are metabolized to an active metabolite, dihydroartemisinin, whose half-life is 2 hr compared with the 45 min half-life of artesunate. 4 Artesunate and dihydroartemisinin are active against severe or complicated P. falciparum malaria. 5 Artesunate contains an endo-peroxide bridge. The peroxide moiety has been demonstrated to be responsible for the antimalarial activity of these compounds 6,7 and presumably for antitoxoplasmal activity. 8 Since these drugs cross the blood-brain barrier, they have been tested as a treatment for toxoplasmosis. To our knowledge, these qinghaosu derivatives have been only tested on the RH strain, a highly virulent strain of Toxoplasma gondii. [8][9][10] The purpose of the present study was to evaluate the in vitro and in vivo effects of artesunate, dihydroartemisinin, and their combination on the cyst-forming strain of T. gondii. MATERIALS AND METHODSParasite. Toxoplasma gondii strain DUR was isolated from the amniotic fluid of a pregnant woman. This isolate is considered to be of low virulence because it causes a chronic infection in mice and grows slowly in culture. This avirulent strain was maintained in our laboratory by oral passage of cysts from the brain of an infected mouse.Cell culture. The human myelomonocytic cell line THP-1 (European Collection of Animal Cell Cultures number 88081201; Sophia-Antipolis, France) was used for T. gondii culture. These non-adherent cells were suspended in RPMI 1640 medium (DAP, Vogelgrun, France) supplemented with 100 U/ml of penicillin, 100 g/ml of streptomycin (SigmaAldrich, L'Isle...

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