Humoral immune response of Simulium damnosum s.l. following filarial and bacterial infections

• Published in: Parasitology Vol. 125; no. 4; pp. 359 - 366
• Main Authors: KLÄGER, S. L., WATSON, A., ACHUKWI, D., HULTMARK, D., HAGEN, H.-E.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.10.2002
• Subjects: Animals; Antibody Formation; Antimicrobial Cationic Peptides - biosynthesis; Antimicrobial Cationic Peptides - immunology; Antimicrobial Cationic Peptides/biosynthesis/immunology; Bacteria; Bacterial diseases; Bacterial Infections - immunology; Bacterial Infections - microbiology; Bacterial Infections/immunology/microbiology; Biological and medical sciences; blackfly; Cattle; Cell Extracts - immunology; Cell Line; Diptera; Drosophila melanogaster; E coli; Electrophoresis, Polyacrylamide Gel; Endotoxins; Escherichia coli; Escherichia coli - immunology; Female; Fundamental and applied biological sciences. Psychology; Hemolymph - chemistry; Hemolymph - immunology; Hemolymph/chemistry/immunology; Immune response; Injection; insect immune response; Lipopolysaccharides - immunology; Medically important nuisances and vectors, pests of stored products and materials: population survey and control; Micrococcus luteus; Micrococcus luteus - immunology; nematode; Onchocerca; Onchocerca - immunology; Onchocerca - microbiology; Onchocerca dukei; Onchocerca/immunology/microbiology; Onchocerciasis - immunology; Onchocerciasis - microbiology; Onchocerciasis/immunology/microbiology; Peptides - blood; Peptides - immunology; Peptides/blood/immunology; Simuliidae; Simuliidae - immunology; Simuliidae - microbiology; Simuliidae - parasitology; Simuliidae/immunology/microbiology/parasitology; Simulium damnosum; Time Factors; Vectors. Intermediate hosts; Wolbachia; Wolbachia - immunology; Onchocerca; nematode; blackfly; Wolbachia; insect immune response; Host parasite relation; Animal microorganism relation; Insecta; Escherichia coli; Simulium damnosum; Endotoxin; Onchocerciasis; Lipopolysaccharide; Bacteria; Nematoda; Vector; Humoral immunity; Enterobacteriaceae; Wolbachieae; Immune response; Simuliidae; Parasitosis; Helminthiasis; Infection; Rickettsiales; Toxin; Experimental disease; Arthropoda; Nematode disease; Helmintha; Bacteriosis; Nemathelminthia; Parasitism; Filariosis; Invertebrata; Diptera; Polyacrylamide Gel; Electrophoresis
• ISSN: 0031-1820; 1469-8161
• DOI: 10.1017/S0031182002002159

The time-course of the humoral immune response of female blackflies after a challenge with bacteria, different Onchocerca microfilariae species, bacterial endotoxin and microfilarial extract was investigated. Strong bacteriolytic and growth inhibition activities against the Gram-positive bacterium Micrococcus luteus were induced by all agents. Specific differences were found in activity levels and time-course. Notably the endotoxin lipopolysaccharide (LPS) induced a very early, profound bacteriolytic and antibacterial response, which declined within a day after injection. In contrast, the bacteriolytic activities after Escherichia coli D31 and Onchocerca microfilariae infections were lower, but remained elevated over the observation period of 4 days. The bacteriolytic activity was correlated to a haemolymph protein with a molecular weight of around 14 kDa. Anti-Gram-positive activity in the E. coli infected group appeared within the first 6 h. However, it took 4 days in the microfilarial infected blackflies to reach significant levels. The active agent was identified to be a peptide with a molecular weight of around 4–4.5 kDa. Activity against the Gram-negative bacteria E. coli was detected in blackflies injected with E. coli D31, O. dukei microfilariae and microfilarial extract on days 1 and 4 after injection. The immune response in S. damnosum s.l. naturally infected via a bloodmeal on cattle supported the findings of the experimental infections. Similarities of the immune response kinetics between bacterial and filarial infections suggested that intracellular Wolbachia bacteria, released from microfilariae, could be responsible for the antibacterial response. This is supported by the observation that the induction of an immune response in the Drosophila melanogaster mbn-2 cell line by the filarial extract is blocked by polymyxin B, which forms inactive complexes with bacterial LPS.