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A cDNA library based on mRNA from oncospheres ofEchinococcus multiloculariswas constructed and screened with an oncosphere-specific rabbit serum. cDNA sequences of three clones that were isolated out of this library are discussed: one codes for a serpin-like proteinase inhibitor, the first isolated from cestodes. Two other clones code for dominant oncosphere antigens and represent homologues of known genes: one is known from several taeniid cestodes as a protective antigen containing fibronectin III domains, the second is related to genes of small heat shock proteins. It contains an internal duplication that might be specific for platyhelminths.A cDNA library based on mRNA from oncospheres ofEchinococcus multiloculariswas constructed and screened with an oncosphere-specific rabbit serum. cDNA sequences of three clones that were isolated out of this library are discussed: one codes for a serpin-like proteinase inhibitor, the first isolated from cestodes. Two other clones code for dominant oncosphere antigens and represent homologues of known genes: one is known from several taeniid cestodes as a protective antigen containing fibronectin III domains, the second is related to genes of small heat shock proteins. It contains an internal duplication that might be specific for platyhelminths.

Infection experiments showed that the African antCamponotus compressiscapus can serve as a second intermediate host ofDicrocoelium hospes. Most of the cercariae penetrated the crop-wall and encysted in the hemocoel, whereas one or more larvae invaded the ant's central nervous system. These larvae cause behavioral changes, which increase their chance of being ingested by final hosts. Experimental infections of definitive hosts were obtained in golden hamsters,Meriones unguiculatus, guinea-pigs, and sheep.

Cerebral larvae ofDicrocoelium dendriticum andD. hospes and the brains of infected ants were studied. Morphologic differences of the freed larvae could not be found, but there were evident differences in number and localization of the cerebral stages. Ants infected withD. dendriticum usually showed one “Hirnwurm” while in the majority of the ants infected withD. hospes two larvae were found.

A purified 41-kDa protein of the rodent filaria Acanthocheilonema viteae was shown to protect jirds against a challenge infection. Subcutaneous immunization with the protein reduced the number of adult worms by up to 65 % and the number of circulating microfilariae declined by up to 93 % in these animals. The protein is located in the muscle tissues of adult worms and was identified as tropomyosin by N-terminal sequencing of the purified protein.