The onchocerciasis program continued its productive activities on the biological and biochemical characterization of the parasite Onchocerca volvulus and on the immunological aspects of the interaction of O. volvulus and Litomosoides sigmodontis with their immunocompetent hosts. The enthusiasm shared between the members of the various groups resulted in the exchange of ideas, methodologies and in productive collaborations. These combined efforts increased our knowledge of the parasite further and helped to understand important aspects of host parasite interactions. Members of the program were invited to national and international meetings and in addition to support from the institute, researchers of the program managed to attract extramural funds from both national and international sources.
Novel filarial molecules have been identified, that may aid in detoxifying activities and tissue modification. A peroxidoxin protein which displays antioxidative activity was cloned and recombinantly expressed and similarly an elastine like protease of low molecular weight was shown to be released by microfilaria.
A further progress during the last months was the characterization of the intracellular bacteria in O. volvulus and in L. sigmodontis. Based on the identified bacterial molecules, these intracellular organisms are identified to the genus Wolbachia. The role of these intracellular bacteria is currently studied in more detail and a tetracycline based therapy used in an animal model destroyed the endobacteria and resulted in filarial infertility.
Additional work concentrated on PCR-based diagnosis of microfilaria in the skin of infected individuals, for the discrimination of anthrophilic and zoophilic population of the Simulium damnosum complexes and on the characterization of the immundiagnostic potential of recombinant O. volvulus proteins. Due to the lack of potent and safe drugs against onchocerciasis and lymphatic filariasis studies of the polyamine metabolism of filarial worms were continued. The potential of S-adenosylmethionine decarboxylase as target for drug development was pursued by expression analysis on a molecular and the whole parasite level.
A large panel of antigens has been identified and cloned during the existence of the onchocerciasis program. The functional characterization of the corresponding proteins, the knowledge about their pattern of regulation, their site of expression within the parasite in combination with the immune profile elicited in the human host, provides an excellent basis to select proper molecules for vaccine and drug development. The test of these antigens or of antigenic peptides in animal models will help to identify protective proteins that may be used for a vaccine against onchocerciasis.

Peter F. Zipfel

Staff  Privatdozent Dr. Peter F. Zipfel, Parasitology, Coordinator Dr. Norbert Brattig, Clinical Chemistry Prof. Dr. Dietrich W. Büttner, Parasitology Privatdozent Dr. Gerd D. Burchard, Tropical Medicine Privatdozent Dr. Klaus D. Erttmann, Parasitology Prof. Dr. Bernhard Fleischer, Medical Microbiology Dr. Michaela Gallin, Parasitology Prof. Dr. Rolf Garms, Parasitology Dr. Kimberly Henkle-Dührsen, Parasitology Dr. Achim Hörauf, Medical Microbiology Prof. Dr. Rolf D. Horstmann, Tropical Medicine Dr. Thomas Kruppa, Parasitology Dr. Christine Skerka, Parasitology Privatdozent Dr. Frank W. Tischendorf, Clinical Chemistry Prof. Dr. Rolf D. Walter, Parasitology Dr. Gabriele Wildenburg, Parasitology Visiting Scientists Dr. Sakari Jokiranta, University of Helsinki, Finland Dr. Wolfgang Prodinger, University of Innsbruck, Austria Doctoral Students Eva Decker, Parasitology Alf Domeyer, Parasitology Andrea Dötze, Medical Microbiology Volker Eckelt, Parasitology Peter Fischer, Parasitology Manuel Friese, Parasitology Judith Gbenoudou, Medical Microbiology Anke Haffner, Clinical Chemistry Jens Hellwage, Parasitology Claudia Kemper, Parasitology Angelika Koszarski, Parasitology Andreas Krüger, Parasitology Josef Mpagi, Parasitology Ulf Rathjens, Clinical Chemistry Erik Schneider, Parasitology Susanne Schröder, Clinical Chemistry Silke Schrum, Parasitology Elizabeth Sentongo, Parasitology Graduate Student Silke Stender, Parasitology Support Staff Marlis Badusche, Medical Microbiology Alexandra Bialonski, Parasitology Marie-Luise Eschbach, Parasitology Frank Geisinger, Clinical Chemistry Silke van Hoorn, Parasitology Claudia Klosse, Parasitology Telse Kock, Parasitology Kerstin Nissen-Pähle, Medical Microbiology Gerd Ruge, Parasitology Eva Taege, Clinical Chemistry

Polytene chromosomes II (long arm) of larvae of sympatric populations of Simulium damnosum s.l. cytotypes (A) `Nyamagasani´ (standard for East Africa), (C) `Nkusi´ with inversion IIL-5 and (B) a heterozygote with a loop containing both standard and IIL-5 from river Mahoma in West Uganda. Only `Nyamagasani´ is highly anthropophilic and a vector of Onchocerca volvulus in East Africa. PB = Paralbalbiani, SWT = Sawtooth. Photo: Andreas Krüger