Combating resistance – discovery tool for new
drenches protecting crop and stock
Technology Type: drug discovery tool
Synopsis: Nematode parasites pose a significant risk to pastoral industries in
New Zealand and worldwide. They are a major animal health issue resulting
in reduced weight gains in livestock, necessitate prolonged maintenance
feeding and can cause illness and death. In order to improve productivity,
livestock are usually treated with anthelmintics or drenches. Drench resistance is becoming an
increasingly widespread, global problem. A mechanism implicated in multiple drench resistance in
nematodes is the pumping of drugs out of their cells by membrane-bound proteins: P-glycoproteins
(ABC transporters, efflux pumps).
Fungal infections of crops are recognised as a global threat to food security; in 2010, persistent
fungal infections of the five major world crop harvests destroyed food that could have fed 595
million people. Farmers respond with broad-spectrum fungicides that have led to a high level of
fungicide resistance. It is estimated that the improved productivity from the use of azoles in Europe
will be € 2.4 billion in 2013. Augmentation of existing drenches and fungicides with efflux pump
inhibitors could make current formulations much more effective.
Department: Oral Sciences, Dunedin Campus
Partners: Walter + Eliza Hall Institute (WEHI) in Australia is well placed to undertake high throughput
screening with this discovery tool (contact: Dr Kurt Lackovic ) – this is optional.
Feature Technology: Otago developed and patented a
screening platform to identify new compounds that inhibit
efflux pumps that cause azole-resistance in fungal
pathogens (to plants and humans) and nematodes. For
highthrougput screening purposes, a fluorescent azole
surrogate is used to quantify pump activity. The assay has
been multiplexed such that viability is simultaneously
assessed using luminescent readout. The NIH dispository
library was screened in collaboration with the University of New Mexico. In collaboration with WEHI,
a pilot screen of 10,000 compounds that included known drugs and diverse lead-like compounds,
was conducted using yeast cells expressing a key fungal efflux pump of Candida. The screening
system is able to express a variety of complex membrane proteins such as human P-glycoprotein and
efflux pumps of fungi and nematodes.
The system also successfully expressed Erg11p from Saccharomyces serevisiae, allowing successful
crystallisation and structural analysis of Erg11p, the first full-length structure containing the N-
terminal membran anchor of a fungal CYP51 – other strucutures are based on truncated or soluble
proteins. Thus this system provides access to great insights for novel crop protection strategies as
well as a useful screening tool to identify specific efflux pump inhibitors. New specific efflux pump
inhibitors will enhance the performance and overcome resistance to existing fungicides and
anthelmintics (same principle as Augmentin: penicillin + clavulanic acid).
Commercial Opportunity: Expression system purchase; co-develpoment for specific targets optional.