The Medical Microbiology Section consists of the Division of Immunology, the Division of Virology and the Central Microbiological Diagnostic Unit. Work of the Division of Immunology is mainly concerned with the interaction of infectious agents with components of the immune system but some work also touches questions of basic immunology related to the immunology of infection such as antigen processing or T cell receptor function. The work on Trypanosoma cruzi was extended. A cooperative project on the T cell immunology of human Chagas’ disease was started with the University of Pernambuco, Recife, Brazil, and is supported by the Volkswagen Foundation. The work in the murine model of Chagas’ disease was continued mainly concerned with origin and pathogenetic role of the strong cytokine response induced by Trypanosoma cruzi. The Division participated in the Onchocerciasis Program of the Institute with a study on the antigen specificity of Onchocerca volvulus-specific T cells from patients in Guinea. As a model system of a filarial infection the full cycle of Litomosoides sigmodontis was established in BALB/c mice using mites as vectors. This model allows a dissection of the protective mechanisms acting early after infection possibly on the L3 stage of the infective larvae. The work on signal transduction in human T cells was further pursued and was extended to bovine T lymphocytes transformed by Theileria parva to analyse the mechanism of transformation.
Within the Division of Virology investigations were performed with the following viruses:
1) HIV-1, 2) Lassavirus, 3) Hantavirus, and 4) Dengueviruses. Work on HIV has been continued within the Hamburg AIDS Program of the Federal Ministry for Education, Science, Research and Technology (BMBF). A gene cassette could be constructed representing the whole envelope of HIV-1 (gp 160), which binds to a second receptor on various lymphocytes and macrophages. In addition, the binding and variability of the gp 160 V3 loops were analysed further. The varying immune reactions in various ethnic groups against different V3 loop proteins of HIV were used to identify infections with different HIV-1 subtypes. Studies of Lassa fever in Guinea resulted in identification of Lassavirus strains possibly showing differing pathogenicities. During field studies in Guinea lymphocytes of patients with Lassa antibodies could be collected. This material will allow research on T cell immunity in humans from areas endemic for Lassa. A new Hantavirus, causing pneumonia in Northern Germany, could be analysed by RT-PCR amplification. Moreover, Hanta RNA could be detected in muskrats. These animals must have been infected with a Puumala-like virus after their introduction to Europe (1905). In the Philippines, studies were performed on Dengue haemorrhagic fever. IgM, IgG antibodies against Dengue virus were detected. Dengue virus could be isolated in tissue culture, and sequences of PCR amplifications could be obtained. The data show that about 70% of cases had a Dengue infection and that Dengue type 2 was predominant in the region studied.
The Central Microbiological Diagnostic Unit performs the direct identification of bacteria, parasites and viruses, serodiagnoses of parasitic, bacterial, rickettsial and viral infections. Because of its specialisation the Unit receives material submitted from all parts of Germany and also from some neighbouring countries. New diagnostic developments are the use of recombinant antigens for diagnosis of amoebiasis and schistosomiasis and the diagnosis of microsporidial infection by a type-specific PCR.
 
 

For additional information please also see Investigators’ Reports.