Host-parasite Interactions at the Hormonal Level in Fasciolosis

Abstract

Fasciolosis is an important disease in ruminants caused by liver flukes of the genus
Fasciola. For the development of new drugs and vaccines it is important to understand the
host/parasite interactions at the molecular level. Vertebrates release a variety of hormones by
which they trigger responses in distant tissues. We investigated whether Fasciola is sensitive
to host hormones and shows specific responses. More specifically, we were interested in
peptide hormones and their receptors which belong to the type II G-protein coupled receptor
family. Structure, function, and pathology of this receptor family have been extensively
studied in vertebrates, especially human and porcine. In contrast, data for host/trematode
interactions at the hormone level are very limited. The latest study dated back 20 years and
focused on changes in muscle contractions of the parasite. Proteomic and nucleic acid
analysis techniques developed in the last decades will allow us to study the effects of
hormones at the molecular level and to identify putative parasite hormone receptors. In the
present study a cDNA encoding a putative type II G-protein coupled receptor of Fasciola was
isolated as a partial product by cDNA library screening and completed by a rapid
amplification of cDNA 5’-end (5’-RACE) method. The deduced amino acid sequence was
compared to the sequences of other members in the type II G-protein couple receptor family
and showed conserved key features of this family. In further studies, the protein will be
localized in the parasite tissue with specific polyclonal antibodies and we would like to
determine which ligand will bind to it and what its biological role is.