Projects and research lines
Gastrointestinal infections by helminths, among them haemonchosis, are highly prevalent and of paramount importance in sheep. The traditional control of these pathologies relied almost entirely on the use of anthelmintics. However, the indiscriminate and massive use of these compounds in sheep farming resulted in the appearance of parasites' isolates resistant to most anthelmintics. Moreover there is a growing concern on the possible presence of pharmacologically active residues in the environment. Therefore, immunoprophylaxis could be an alternative.
The objective of our ongoing project is the cloning and expression, by DNA recombinant technology, of a protein (p26/23) able to elicit a protective response in lambs against Haemonchus contortus challenge. This protein is naturally expressed (see above) in the hypodermic chords from adult parasites (http://www.springerlink.com/content/8688972731912k77/fulltext.pdf) and has potential immunoprotective effect in sheep haemonchosis. We plan to produce this recombinant protein in Escherichia coli and nematode cells to determine its role on the reduction of pathophysiological alterations and abomasal parasite burdens in challenged lambs.
We have obtained the recombinant protein (rpHc26/23) using a prokaryotic expression system. Partial sequencing of the recombinant product shows high homology with a hypothetic protein deduced from a cDNA library (HCC00515). Preliminary trials on the immunogenicity of the protein for lambs are in progress.
The effect of skin estimulation with homologous (H.contortus) and heterologous alergens on the immune response against intestinal infections by nematodes (SALT/GALT interaction) is an interesting aspect of helminth diseases. This task is approached by us with a model of gastric infection with helminths (Graphidium strigosum/ rabbit stomach) with the final aim of applying the results (immunization schedule, adjuvants, doses) to gastrointestinal helminth infections in ruminants. Unfortunately information on the G.strigosum/rabbit relationship is very scarce. Moreover there was no availability of isolates of the nematode for experimental infections. Recently we have obtained a wild isolate of the rabbit nematode species in Central Spain. The isolate has been successfully maintained and a preliminary characterization of experimental infection in rabbits carried out. See the link below for details. (http://www.springerlink.com/content/g468063jtpt81461/fulltext.pdf).
A collaborative effort with Prof. B. Valladares (Department of Parasitology, School of Pharmacy, Universidad de La Laguna) allowed us to obtain a cDNA library of H.contortus. This tool will be used to explore the immunoprotective potential of other proteins. [Research project funded by MICINN AGL2006-10589].
The p26/23 encoding gene has been isolated and the recombinant protein has been expressed and purified (rHcp26/23). Immunisation trials in lambs have shown a remarkable protective effect against Haemonchus contortus. Patent claims (nationald and international) protecting the production and purification of the recombinant protein (rHc23) and the immunisation protocol have been presented.
Leishmaniases are a heterogeneous group of parasitic diseases affecting animals, including humans, caused by the infection with Leishmania species. The disease is present in all inhabited continents. Clinical course varies from self-curing to fatal visceral leishmaniasis. The spectral characteristics of the infection are dependent on the Leishmania species involved, host affected and the immunological status of the infected individual. It is estimated that 12 million people are currently infected and every year two million new cases are reported. The disease once linked almost exclusively to tropical and subtropical areas nowadays has reached higher relevance in developed countries as one of the cohort infections present in HIV-infected people.
Besides the human cases in some regions of the world (see map of distribution) canine leishmaniasis is very common with prevalence exceeding 30% of the total dog population in endemic areas. This situation is present, among other places, in areas of Southern Europe. On these grounds, infected dogs with L. infantum are considered the reservoir for human infections by this species. It is clear that the simultaneous presence of parasitic agent, susceptible humans and dogs, makes the control of canine leishmaniasis a "must" to effectively limit the extension of human cases.
Among possible strategies to limit the extension of leishmaniasis (vector control, immunisation, chemotherapy) treatment of infected animals is, by large, the most widely used practice. Unfortunately, Leishmania isolates resistant to antimonials (first choice chemotherapy) have been detected and the toxicity of these compounds is high. More recently introduced drugs (liposome amphotericin, paromomycin, miltefosine) are far from ideal and the exploration of new treatments is one of the priorities in leishmaniasis research.
Our approach is based on some principles:
· Conventional chemotherapy of leishmaniasis, both human and canine, is inadequate (toxicity, absence of parasitological cure of infected individuals)
· Newly introduced compounds are less than ideal (teratogenicity, high cost)
· New treatments against Leishmania are required
· Screening methods to select potential chemotherapeutic agents have been carried out, in general, using models of low predictive value in the actual species naturally affected by Leishmania.
Our objective, on the above considerations, is to develop drug screening methods, both in vivo and in vitro, of high predictive capacity in natural infections. In addition we want to explore new low-cost formulations of effective drugs and identify specific therapeutic targets. Within our approach microcapsules of human albumin, containing amphotericin, have been developed; an in vitro model of infection with amastigotes of L.infantum in macrophages (J774) has been established; some immunobiological characteristics of the infection by this parasite in a vertebrate host model (Mesocricetus auratus, hamster) have been determined; the anti-leishmanial effect of some recombinant phytocistatins has been preliminarily explored. Infection method of macrophages (cell lines, peritoneal macrophages) with Leishmania infantum has been refined and employed to test antileishmanial activity of betulin derivatives and allicin. [COST Action CM0801] [Research funded by MICINN AGL2009-13009]
Recently a project from the EU has been obtained [NMTrypl- New Medicines for Trypanosomatidic Infections, FP7- Innovation]. Project will start by January 2014.
Humans and their domestic animals share over 200 transmissible diseases, many of them parasitic diseases. These infections affecting both humans and non-human animals and the infections transmitted from animals to man are called zoonoses. Parasitic diseases of paramount interest in the most developed areas of the world as well as in regions with deficient sanitary conditions use domestic animals as natural reservoirs. In this way, some worldwide parasitic diseases affecting men such as toxoplasmosis, trichinellosis or hydatid disease, are acquired through the ingestion of contaminated meat or are related to the close contact between men and their pets.
Control measures established by Public Health authorities (government officers, medical services, veterinary inspection services) have limited to a great extent the risks associated to the man-animal coexistence. However, there is a growing interest of the population from developed countries in the preservation of environmental resources. Social benefits associated to the management of natural resources and the economic interest from employees linked to this sector, have provoked an increasing close contact between humans and wild animals (game activities, conservation, production, recreation). In large areas from Spain cohabitation of wild and domestic animals is frequent. Scientists consider that
· It is relevant to know the presence of transmissible agents –among them parasites- to man in the wild animals
· It is necessary to study the possible transmission, two ways, of parasites from wild and domestic animals
Exploitation of domestic and wild animals is extremely different even in the cases where only a semi-natural management is used. Therefore, the transmission patterns of parasites surely have peculiarities in wild animals. As a consequence epidemiological models useful for domestic animals should be reconsidered to be useful in the understanding of the wild / domestic animal interface. This aspect requires different experimental approaches from those currently employed in the epidemiological studies of parasitic diseases from domestic animals.