Insecticide resistance is the major cause of vector control failure. Metabolism based detoxification of insecticides is one of the principle mechanisms of resistance.
The majority of these reactions involve cytochomes P450s. In humans, liver P450s influence drug metabolism, while in insects P450s control the metabolism and disposition of insecticides. Historically, the discovery of metabolic resistance to an insecticide occurs after the fact. The availability of recombinant P450s allows the development of in vitro assays to screen for potential resistance liabilities of insecticide compounds as well as P450 inhibitors for potential synergistic effects in early stages of insecticide discovery.
Mosquitoes transmit many diseases including malaria, dengue, zika and chikengunya. Mosquito P450s associated with insecticide metabolism have been identified. The major P450s associated with pyrethroid resistance in An gambiae (CYP6M2, CYP6P3), An. funestus (CYP6P9a) and Ae. aegypti (CYP9J32) have been expressed commercially for the development of in vitro assays such as:
- Biochemical characterisation of insecticide metabolism
- High throughput screening of P450 inhibition potential of compounds
- Understanding insecticide/insect interactions
- Guiding the development of vector control compounds
Mosquito P450s commercially available from LITE
P450 |
Species |
Insecticide’s metabolised |
Refs |
|
CYP6P3 |
An. gambiae |
Pyrethroids (deltamethrin, permethrin) |
Muller (2008) PLoS genetics 4 |
|
CYP6M2 |
An. gambiae |
Pyrethroids (deltamethrin, permethrin), |
Stevenson, B.J., et al. (2011) IBMB 41, 492-502
|
|
CYP6P9a |
An. funestus |
Pyrethroids (deltamethrin, permethrin, bifenthrin, etofenprox) |
Riveron (2013) PNAS 110, 252-257 |
|
CYP9J32 |
Ae. aegypti |
Pyrethroids (deltamethrin, permethrin). |
Stevenson et al (2012) PLoS neglected tropical diseases 6 |
References
(Muller et al. 2008)(Stevenson et al. 2011)(Riveron et al. 2013)(Stevenson et al. 2012)
Muller, P. et al., 2008. Field-Caught Permethrin-Resistant Anopheles gambiae Overexpress CYP6P3, a P450 That Metabolises Pyrethroids. PLoS Genet, 4(11). Available at: <Go to ISI>://000261481000039.
Riveron, J.M. et al., 2013. Directionally selected cytochrome P450 alleles are driving the spread of pyrethroid resistance in the major malaria vector Anopheles funestus. Proc Natl Acad Sci U S A, 110(1), pp.252–257. Available at: http://www.pnas.org/content/110/1/252.abstract.
Stevenson, B.J. et al., 2011. Cytochrome P450 6M2 from the malaria vector Anopheles gambiae metabolizes pyrethroids: Sequential metabolism of deltamethrin revealed. Insect Biochem Mol Biol, 41(7), pp.492–502. Available at: <Go to ISI>://000293041200010.
Stevenson, B.J. et al., 2012. Pinpointing P450s Associated with Pyrethroid Metabolism in the Dengue Vector, Aedes aegypti: Developing New Tools to Combat Insecticide Resistance. PLoS Negl Trop Dis, 6(3). Available at: <Go to ISI>://000302132100036.