Carbohydrate Catabolism in Adult &amp;lt;i&amp;gt;Onchocerca volvulus:&amp;lt;/i&amp;gt; An Immunohistochemical Study

Seidu Mahmood Abdulai

doi:10.11648/j.ajbls.20160403.13

Abstract

Onchocerca volvulus is a parasite responsible for Onchocerciasis whose main pathology is blindness. Existing treatment and control approaches are not entirely successful, with some, fraught with safety challenges. Due to these problems, the need for developing safer and effective drugs to combat the disease has become imperative. However O. volvulus materials are restricted by ethical concerns due to its strict human preference. To overcome these concerns some researchers use animal models of closely related species to obtain biological information on O. volvulus and drugs developed from these sources of information have so far failed to kill the adult O. volvulus. Realistic targets for drug development against O. volvulus could be detected directly in O. volvulus rather than its closely related species. We performed immunohistochemical detection of three major enzymes (G6PD, LDH and PDHK2) involved in carbohydrate metabolism on paraffin processed archival O. volvulus nodules. We observed that up to 64.5% of worms in the paraffin processed nodules had detectable LDH, 61.1% had G6PD and 56.7% had PDHK2 and that most of the enzymes were stored in the muscles of the adult worm. These observations suggest that the adult O. volvulus can operate the glycolytic, Pentose and Entner-Douhoroff pathways either independently or concurrently suggesting that any drug aimed at preventing the adult worm from utilising carbohydrates must target all three enzymes.

Highlights

Onchocerciasis, or River Blindness, is a neglected tropical disease caused by the parasitic worm Onchocerca volvulus
There are reports that there are complications associated with the administration of ivermectin to individuals co-infected with O. volvulus and Loa loa [10, 11]
Thirty paraffin embedded O. volvulus nodules were obtained from Onchocerciasis Chemotherapy Research Centre (OCRC) in the Volta Region of Ghana, cleaned and re-embedded using fresh paraffin wax (Leica histowax, mp 57-58°C; Leica Microsystems GmbH, Germany) in freshly labeled cassettes as described in our previous publication [18]

Summary

Introduction

Onchocerciasis, or River Blindness, is a neglected tropical disease caused by the parasitic worm Onchocerca volvulus. The ideal treatment requires drugs which will kill the adult worms (macrofilarici Zdes) or permanently eliminate all microfilariae (microfilaricides) including those in gravid adult female worms in the infected individual. The only safe filaricide is ivermectin which is a microfilaricide and can only control onchocerciasis when it is administered once a year throughout the life span of the adult worm. This approach could take up to 15 years or more considering the reported long life-spans of adult filarial worms [9]. There are reports that there are complications associated with the administration of ivermectin to individuals co-infected with O. volvulus and Loa loa [10, 11]

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