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The Cytochrome P450 gene CYP6P12 confers pyrethroid resistance in kdr-free Malaysian populations of the dengue vector Aedes albopictus.

Ishak IH, Riveron JM, Ibrahim SS, Stott R, Longbottom J, Irving H, Wondji CS - Sci Rep (2016)

Bottom Line: Microarray-based transcription profiling revealed that metabolic resistance (cytochrome P450 up-regulation) and possibly a reduced penetration mechanism (consistent over-expression of cuticular protein genes) were associated with pyrethroid resistance.CYP6P12 over-expression was strongly associated with pyrethroid resistance whereas CYP6N3 was rather consistently over-expressed across carbamate and DDT resistant populations.The major role played by P450 in the absence of kdr mutations suggests that addition of the synergist PBO to pyrethroids could improve the efficacy of this insecticide class and overcome resistance in field populations of Ae. albopictus.

View Article: PubMed Central - PubMed

Affiliation: Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, United Kingdom.

ABSTRACT
Control of Aedes albopictus, major dengue and chikungunya vector, is threatened by growing cases of insecticide resistance. The mechanisms driving this resistance remain poorly characterised. This study investigated the molecular basis of insecticide resistance in Malaysian populations of Ae. albopictus. Microarray-based transcription profiling revealed that metabolic resistance (cytochrome P450 up-regulation) and possibly a reduced penetration mechanism (consistent over-expression of cuticular protein genes) were associated with pyrethroid resistance. CYP6P12 over-expression was strongly associated with pyrethroid resistance whereas CYP6N3 was rather consistently over-expressed across carbamate and DDT resistant populations. Other detoxification genes also up-regulated in permethrin resistant mosquitoes included a glucuronosyltransferase (AAEL014279-RA) and the glutathione-S transferases GSTS1 and GSTT3. Functional analyses further supported that CYP6P12 contributes to pyrethroid resistance in Ae. albopictus as transgenic expression of CYP6P12 in Drosophila was sufficient to confer pyrethroid resistance in these flies. Furthermore, molecular docking simulations predicted CYP6P12 possessing enzymatic activity towards pyrethroids. Patterns of polymorphism suggested early sign of selection acting on CYP6P12 but not on CYP6N3. The major role played by P450 in the absence of kdr mutations suggests that addition of the synergist PBO to pyrethroids could improve the efficacy of this insecticide class and overcome resistance in field populations of Ae. albopictus.

No MeSH data available.


Related in: MedlinePlus

Transcription profiling of Ae. albopictus in Malaysia: (a) Summary of probes differentially expressed for permethrin comparisons for the Kuala Lumpur (KL) population, whereas (b) is for C-S comparisons from KL (Kuala Lumpur), PG (Penang) and JB (Johor Bharu). The Venn diagrams show the number of probes (or ESTs) significantly (P value < 0.01) up- or down-regulated (>2 fold change) in each comparison as well as the commonly expressed probes. Upward arrows indicate up-regulated probes while downward represent down-regulated. (c) Differential expression by qRT-PCR of 11 genes up-regulated in microarray in the four locations. Statistical significance is indicated by ***for P < 0.001; **for P < 0.01: *for P < 0.05 and ns is for non-significant of fold-change in comparison to the susceptible strain VCRU.
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f2: Transcription profiling of Ae. albopictus in Malaysia: (a) Summary of probes differentially expressed for permethrin comparisons for the Kuala Lumpur (KL) population, whereas (b) is for C-S comparisons from KL (Kuala Lumpur), PG (Penang) and JB (Johor Bharu). The Venn diagrams show the number of probes (or ESTs) significantly (P value < 0.01) up- or down-regulated (>2 fold change) in each comparison as well as the commonly expressed probes. Upward arrows indicate up-regulated probes while downward represent down-regulated. (c) Differential expression by qRT-PCR of 11 genes up-regulated in microarray in the four locations. Statistical significance is indicated by ***for P < 0.001; **for P < 0.01: *for P < 0.05 and ns is for non-significant of fold-change in comparison to the susceptible strain VCRU.

Mentions: Due to the major role of pyrethroid in ongoing vector control interventions against dengue vectors in Malaysia, emphasis was put in investigating the underlying metabolic resistance mechanisms against permethrin. The KL sample was chosen for this study as it was the only location where Ae. albopictus was resistant to permethrin14. In addition, the relatively lower level of permethrin resistance in KL also makes it more relevant to compare resistant mosquitoes to non-exposed control sample from KL. The large phenotypic difference between the permethrin resistant mosquitoes (100% resistant, since all survivors are considered resistant) and the control non-exposed (only 13% resistant since there was a mortality of 87% after exposure to permethrin) present a higher contrast likely to facilitate the detection of permethrin resistance genes by microarray hybridisation between resistant (R) and Control (C) (R-C) as there is no confounding factor caused by the difference in genetic background. Furthermore, the permethrin resistant mosquitoes (R) were also compared to the lab permethrin susceptible (S) VCRU strain (R-S) to further validate the consistency of the expression pattern of candidate resistance genes. The possible induction of some genes in the R-C and R-S comparisons because of the exposure to insecticide was corrected by also performing a comparison of the control non exposed mosquitoes (C) to the susceptible ones (S) (C-S). Overall, the expression profiles from the three R-C, R-S and C-S hybridisations were used to generate the list of candidate resistance genes as presented in Table S1. The number of differentially expressed probes was determined with a cut-off of >2-fold at P < 0.01 for each comparison as indicated in Fig. 2a.


The Cytochrome P450 gene CYP6P12 confers pyrethroid resistance in kdr-free Malaysian populations of the dengue vector Aedes albopictus.

Ishak IH, Riveron JM, Ibrahim SS, Stott R, Longbottom J, Irving H, Wondji CS - Sci Rep (2016)

Transcription profiling of Ae. albopictus in Malaysia: (a) Summary of probes differentially expressed for permethrin comparisons for the Kuala Lumpur (KL) population, whereas (b) is for C-S comparisons from KL (Kuala Lumpur), PG (Penang) and JB (Johor Bharu). The Venn diagrams show the number of probes (or ESTs) significantly (P value < 0.01) up- or down-regulated (>2 fold change) in each comparison as well as the commonly expressed probes. Upward arrows indicate up-regulated probes while downward represent down-regulated. (c) Differential expression by qRT-PCR of 11 genes up-regulated in microarray in the four locations. Statistical significance is indicated by ***for P < 0.001; **for P < 0.01: *for P < 0.05 and ns is for non-significant of fold-change in comparison to the susceptible strain VCRU.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4837359&req=5

f2: Transcription profiling of Ae. albopictus in Malaysia: (a) Summary of probes differentially expressed for permethrin comparisons for the Kuala Lumpur (KL) population, whereas (b) is for C-S comparisons from KL (Kuala Lumpur), PG (Penang) and JB (Johor Bharu). The Venn diagrams show the number of probes (or ESTs) significantly (P value < 0.01) up- or down-regulated (>2 fold change) in each comparison as well as the commonly expressed probes. Upward arrows indicate up-regulated probes while downward represent down-regulated. (c) Differential expression by qRT-PCR of 11 genes up-regulated in microarray in the four locations. Statistical significance is indicated by ***for P < 0.001; **for P < 0.01: *for P < 0.05 and ns is for non-significant of fold-change in comparison to the susceptible strain VCRU.
Mentions: Due to the major role of pyrethroid in ongoing vector control interventions against dengue vectors in Malaysia, emphasis was put in investigating the underlying metabolic resistance mechanisms against permethrin. The KL sample was chosen for this study as it was the only location where Ae. albopictus was resistant to permethrin14. In addition, the relatively lower level of permethrin resistance in KL also makes it more relevant to compare resistant mosquitoes to non-exposed control sample from KL. The large phenotypic difference between the permethrin resistant mosquitoes (100% resistant, since all survivors are considered resistant) and the control non-exposed (only 13% resistant since there was a mortality of 87% after exposure to permethrin) present a higher contrast likely to facilitate the detection of permethrin resistance genes by microarray hybridisation between resistant (R) and Control (C) (R-C) as there is no confounding factor caused by the difference in genetic background. Furthermore, the permethrin resistant mosquitoes (R) were also compared to the lab permethrin susceptible (S) VCRU strain (R-S) to further validate the consistency of the expression pattern of candidate resistance genes. The possible induction of some genes in the R-C and R-S comparisons because of the exposure to insecticide was corrected by also performing a comparison of the control non exposed mosquitoes (C) to the susceptible ones (S) (C-S). Overall, the expression profiles from the three R-C, R-S and C-S hybridisations were used to generate the list of candidate resistance genes as presented in Table S1. The number of differentially expressed probes was determined with a cut-off of >2-fold at P < 0.01 for each comparison as indicated in Fig. 2a.

Bottom Line: Microarray-based transcription profiling revealed that metabolic resistance (cytochrome P450 up-regulation) and possibly a reduced penetration mechanism (consistent over-expression of cuticular protein genes) were associated with pyrethroid resistance.CYP6P12 over-expression was strongly associated with pyrethroid resistance whereas CYP6N3 was rather consistently over-expressed across carbamate and DDT resistant populations.The major role played by P450 in the absence of kdr mutations suggests that addition of the synergist PBO to pyrethroids could improve the efficacy of this insecticide class and overcome resistance in field populations of Ae. albopictus.

View Article: PubMed Central - PubMed

Affiliation: Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, United Kingdom.

ABSTRACT
Control of Aedes albopictus, major dengue and chikungunya vector, is threatened by growing cases of insecticide resistance. The mechanisms driving this resistance remain poorly characterised. This study investigated the molecular basis of insecticide resistance in Malaysian populations of Ae. albopictus. Microarray-based transcription profiling revealed that metabolic resistance (cytochrome P450 up-regulation) and possibly a reduced penetration mechanism (consistent over-expression of cuticular protein genes) were associated with pyrethroid resistance. CYP6P12 over-expression was strongly associated with pyrethroid resistance whereas CYP6N3 was rather consistently over-expressed across carbamate and DDT resistant populations. Other detoxification genes also up-regulated in permethrin resistant mosquitoes included a glucuronosyltransferase (AAEL014279-RA) and the glutathione-S transferases GSTS1 and GSTT3. Functional analyses further supported that CYP6P12 contributes to pyrethroid resistance in Ae. albopictus as transgenic expression of CYP6P12 in Drosophila was sufficient to confer pyrethroid resistance in these flies. Furthermore, molecular docking simulations predicted CYP6P12 possessing enzymatic activity towards pyrethroids. Patterns of polymorphism suggested early sign of selection acting on CYP6P12 but not on CYP6N3. The major role played by P450 in the absence of kdr mutations suggests that addition of the synergist PBO to pyrethroids could improve the efficacy of this insecticide class and overcome resistance in field populations of Ae. albopictus.

No MeSH data available.


Related in: MedlinePlus