Retarded Onchocerca volvulus L1 to L3 larval development in the Simulium damnosum vector after anti-wolbachial treatment of the human host

Particle and Fibre Toxicology

Kenneth Pfarr³  Achim Hoerauf³  Samuel Wanji⁴  Ute Klarmann¹  Peter Enyong²  Nicholas Tendongfor⁴  Mathias Eyong Esum⁵  Anna Albers³ 

[1] Institute for Medical Biometry, Informatics and Epidemiology, University Hospital Bonn, Sigmund-Freud-Str. 25, D-53105 Bonn, Germany;Research Foundation for Tropical Diseases and the Environment, P.O. Box 474, Buea, Cameroon;Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Sigmund-Freud-Str. 25, D-53105 Bonn, Germany;Department of Biochemistry and Microbiology, Faculty of Science, University of Buea, P.O. Box 63, Buea, Cameroon;Department of Plant and Animal Sciences, Faculty of Science, University of Buea, P.O. Box 63, Buea, Cameroon

关键词: onchocerciasis;    development;    doxycycline;    Wolbachia;    Onchocerca volvulus;   

Others  :  1233123
DOI  :  10.1186/1756-3305-5-12

 received in 2011-08-19, accepted in 2012-01-11,  发布年份 2012

【 摘 要 】

Background

The human parasite Onchocerca volvulus harbours Wolbachia endosymbionts essential for worm embryogenesis, larval development and adult survival. In this study, the development of Wolbachia-depleted microfilariae (first stage larvae) to infective third stage larvae (L3) in the insect vector Simulium damnosum was analysed.

Methods

Infected volunteers in Cameroon were randomly and blindly allocated into doxycycline (200 mg/day for 6 weeks) or placebo treatment groups. After treatment, blackflies were allowed to take a blood meal on the volunteers, captured and dissected for larval counting and DNA extraction for quantitative real-time PCR analysis.

Results

PCR results showed a clear reduction in Wolbachia DNA after doxycycline treatment in microfilariae from human skin biopsies with > 50% reduction at one month post-treatment, eventually reaching a reduction of > 80%. Larval stages recovered from the insect vector had similar levels of reduction of endosymbiotic bacteria. Larval recoveries were analysed longitudinally after treatment to follow the kinetics of larval development. Beginning at three months post-treatment, significantly fewer L3 were seen in the blackflies that had fed on doxycycline treated volunteers. Concomitant with this, the proportion of second stage larvae (L2) was significantly increased in this group.

Conclusions

Doxycycline treatment and the resulting decline of Wolbachia endobacteria from the microfilaria resulted in retarded development of larvae in the insect vector. Thus, anti-wolbachial treatment could have an additive effect for interrupting transmission by reducing the number of L3 that can be transmitted by blackflies.

【 授权许可】

   
2012 Albers et al; licensee BioMed Central Ltd.

【 图 表 】

Figure 1.

Figure 2.

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