P-glycoproteins play a role in ivermectin resistance in cyathostomins

Population pharmacokinetics of ivermectin after mass drug administration in lymphatic filariasis endemic communities of Tanzania

Ivermectin (IVM) is a drug of choice used with albendazole for mass drug administration (MDA) to halt transmission of lymphatic filariasis. We investigated IVM pharmacokinetic (PK) variability for its dose optimization during MDA. PK samples were collected at 0, 2, 4, and 6 h from individuals weighing greater than 15 kg (n = 468) receiving IVM (3-, 6-, 9-, or 12 mg) and ALB (400 mg) during an MDA campaign in Tanzania. Individual characteristics, including demographics, laboratory/clinical parameters, and pharmacogenetic variations were assessed. IVM plasma concentrations were quantified by liquid-chromatography tandem mass spectrometry and analyzed using population-(PopPK) modeling. A two-compartment model with transit absorption kinetics, and allometrically scaled oral clearance (CL/F) and central volume (Vc /F) was adapted. Fitting of the model to the data identified 48% higher bioavailability for the 3 mg dose compared to higher doses and identified a subpopulation with 97% higher mean transit time (MTT). The final estimates for CL/F, Vc /F, intercompartment clearance, peripheral volume, MTT, and absorption rate constant for a 70 kg person (on dose other than 3 mg) were 7.7 L/h, 147 L, 20.4 L/h, 207 L, 1.5 h, and 0.71/h, respectively. Monte-Carlo simulations indicated that weight-based dosing provides comparable exposure across weight bands, but height-based dosing with capping IVM dose at 12 mg for individuals with height greater than 160 cm underdoses those weighing greater than 70 kg. Variability in IVM PKs is partly explained by body weight and dose. The established PopPK model can be used for IVM dose optimization. Height-based pole dosing results in varying IVM exposure in different weight bands, hence using weighing scales for IVM dosing during MDA is recommended.

Evidence of resistance to ivermectin in the gastrointestinal nematodes of horses from Mexican southeast

Gastrointestinal nematodes (GIN) are a major impediment to breeding and exploitation of horses. Traditional control of GIN has generated resistance to main anthelmintics, including ivermectin. An analysis of five ranches with a history of IVM use was done to determine the efficacy and resistance of GIN to IVM treatment in horses from the Mexican southeast. Predesigned questionnaires were applied to collect information on previous treatment protocols. The fecal egg count reduction test (FECRT) was applied to determine resistance. Before IVM application, a McMaster test was used to diagnose GIN infection in horses, and feces cultures were done to identify L3 larvae for Strongylida eggs. Pre-treatment samples showed that 72.7% (80/110) of horses were GIN positive, with cyathostomins being the most frequent (91.8%), followed by Oxyuris equi (7.0%), Parascaris equorum (1.0%), and Strongylus vulgaris (0.2%). Based on the results, the horses at each ranch were divided in control (CG) and experimental (EG) groups with similar eggs per gram of feces (EPG). The EG (40/80) was dewormed with IVM (0.2 mg/kg orally) and the CG (40/80) remained untreated. After 14 days, EPG were measured, and feces cultures were done again to identify L3 larvae. After treatment of EG, 40% (16/40) of horses were positive, the most frequently identified GIN were cyathostomins (98.6%), followed by P. equorum (1.0%) and S. vulgaris (0.2%). Three of the five ranches were classified as resistant, according to the FECRT, with a percentage of reduction from 53 to 68%, all of which used IVM ≥4 times annually. This is the first evidence of resistance in cyathostomins to IVM treatment in horses from the Mexican southeast, adding to the current problem of anthelmintic resistance in equine GIN.

Importance of ABC Transporters in the Survival of Parasitic Nematodes and the Prospect for the Development of Novel Control Strategies

ABC transporters, a family of ATP-dependent transmembrane proteins, are responsible for the active transport of a wide range of molecules across cell membranes, including drugs, toxins, and nutrients. Nematodes possess a great diversity of ABC transporters; however, only P-glycoproteins have been well-characterized compared to other classes. The ABC transport proteins have been implicated in developing resistance to various classes of anthelmintic drugs in parasitic nematodes; their role in plant and human parasitic nematodes still needs further investigation. Therefore, ABC transport proteins offer a potential opportunity to develop nematode control strategies. Multidrug resistance inhibitors are becoming more attractive for controlling nematodes due to their potential to increase drug efficacy in two ways: (i) by limiting drug efflux from nematodes, thereby increasing the amount of drug that reaches its target site, and (ii) by reducing drug excretion by host animals, thereby enhancing drug bioavailability. This article reviews the role of ABC transporters in the survival of parasitic nematodes, including the genes involved, their regulation and physiological roles, as well as recent developments in their characterization. It also discusses the association of ABC transporters with anthelmintic resistance and the possibility of targeting them with next-generation inhibitors or nutraceuticals (e.g., polyphenols) to control parasitic infections.

Molecular diagnostics for gastrointestinal helminths in equids: Past, present and future

This review is aimed to (i) appraise the literature on the use of molecular techniques for the detection, quantification and differentiation of gastrointestinal helminths (GIH) of equids, (ii) identify the knowledge gaps and, (iii) discuss diagnostic prospects in equine parasitology. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines for systematic reviews, we retrieved 54 studies (horses: 50/54; donkeys and zebras: 4/54) from four databases. Polymerase chain reaction (PCR) was employed in all of the studies whereas PCR amplicons were sequenced in only 18 of them. Other techniques used (including modifications of PCR) were reverse line blot, quantitative (q)PCR, restriction fragment length polymorphism, nested-PCR, PCR-directed next-generation sequencing, Southern blotting, single strand conformation polymorphism, PCR-enzyme linked immunosorbent assay, matrix-assisted laser desorption/ionisation-time of flight and random amplification of polymorphic DNA. Most of the studies (53/54) used nuclear ribosomal RNA (including the internal transcribed spacers, intergenic spacer, 5.8 S, 18 S, 28 S and 12 S) as target loci while cytochrome c oxidase subunit 1 and random genomic regions were targeted in only three and one studies, respectively. Overall, to date, the majority of molecular studies have focused on the diagnosis and identification of GIHs of equids (i.e. species of Anoplocephala, Craterostomum, cyathostomins, Oesophagodontus, Parascaris, Strongylus, Strongyloides and Triodontophorus), with a recent shift towards investigations on anthelmintic resistance and the use of high-throughput nemabiome metabarcoding. With the increasing reports of anthelmintic resistance in equid GIHs, it is crucial to develop and apply techniques such as advanced metabarcoding for surveillance of parasite populations in order to gain detailed insights into their diversity and sustainable control. To the best of our knowledge, this is the first systematic review that evaluates molecular investigations published on the diagnosis and quantification of equid GIHs and provides useful insights into important knowledge gaps and future research directions in equid molecular parasitology.

In silico analysis of koranimine, a cyclic imine compound from Peribacillus frigoritolerans reveals potential nematicidal activity

Pine wilt disease (PWD) is a destructive vector-borne forest disease caused by the nematode Bursaphelenchus xylophilus. To date, several options are available for the management of pine wilt disease; however constant development and search for natural products with potential nematicidal activity are imperative to diversify management options and to cope with the possible future emergence of resistance in parasitic nematodes. Here, a combined metabolomics and genomics approach was employed to investigate the chemical repertoire and biosynthetic potential of the bacterial endophyte Peribacillus frigoritolerans BE93, previously characterized to exhibit nematicidal activity against B. xylophilus. Feature-based molecular networking revealed the presence of diverse secondary metabolites. A cyclic imine heptapeptide, koranimine, was found to be among the most abundant secondary metabolites produced. Genome mining displayed the presence of several putative biosynthetic gene clusters (BGCs), including a dedicated non-ribosomal peptide synthase (NRPS) BGC for koranimine. Given the non-ribosomal peptide nature of koranimine, in silico molecular docking analysis was conducted to investigate its potential nematicidal activity against the target receptor ivermectin-sensitive invertebrate α glutamate-gated chloride channel (GluCl). Results revealed the binding of koranimine at the allosteric site of the channel-the ivermectin binding site. Moreover, the ligand-receptor interactions observed were mostly shared between koranimine and ivermectin when bound to the α GluCl receptor thus, suggesting a possibly shared mechanism of potential nematicidal activity. This study highlights the efficiency of combined metabolomics and genomics approach in the identification of candidate compounds.

Transporter gene expression and Wolbachia quantification in adults of Dirofilaria immitis treated in vitro with ivermectin or moxidectin alone or in combination with doxycycline for 12 hours

Due to their marked larvicidal activity, macrocyclic lactones (MLs) are used for the prevention of heartworm disease ( Dirofilaria immitis) in dogs. They have also been shown to eliminate adult parasites after long-term administration, with a so-called "slow-kill" effect. In addition, recent studies have established that a combination of doxycycline, which eliminates the endosymbiont Wolbachia, and MLs has superior adulticide effects when compared to MLs alone. It has been hypothesized that the apparent synergism between doxycycline/MLs may be due to interaction with drug efflux transport proteins. The aim of the present study was to evaluate gene expression of several transport proteins in D. immitis adults treated in vitro either with doxycycline alone, ivermectin alone, moxidectin alone, or a combination of ivermectin or moxidectin with doxycycline for 12h. Quantitative PCR analysis showed a sex-dependent response to treatments. In female worms, Dim-pgp-10, Dim-haf-1 and Dim-haf-5 were upregulated compared to controls with doxycycline alone and when combined with ivermectin. Moxidectin did not induce any changes in gene expression. In males, moxidectin administered alone induced a slight increase in Dim-pgp-10, Dim-pgp-11and Di-avr-14, while ivermectin in combination with doxycycline produced significant upregulation of the ML receptor Di-avr-14. These results suggest possible synergism between the two drug classes and different susceptibility of males vs. females to adulticide effects.

Pharyngeal Pumping and Tissue-Specific Transgenic P-Glycoprotein Expression Influence Macrocyclic Lactone Susceptibility in Caenorhabditis elegans

Macrocyclic lactones (MLs) are widely used drugs to treat and prevent parasitic nematode infections. In many nematode species including a major pathogen of foals, Parascaris univalens, resistance against MLs is widespread, but the underlying resistance mechanisms and ML penetration routes into nematodes remain unknown. Here, we examined how the P-glycoprotein efflux pumps, candidate genes for ML resistance, can modulate drug susceptibility and investigated the role of active drug ingestion for ML susceptibility in the model nematode Caenorhabditis elegans. Wildtype or transgenic worms, modified to overexpress P. univalens PGP-9 (Pun-PGP-9) at the intestine or epidermis, were incubated with ivermectin or moxidectin in the presence (bacteria or serotonin) or absence (no specific stimulus) of pharyngeal pumping (PP). Active drug ingestion by PP was identified as an important factor for ivermectin susceptibility, while moxidectin susceptibility was only moderately affected. Intestinal Pun-PGP-9 expression elicited a protective effect against ivermectin and moxidectin only in the presence of PP stimulation. Conversely, epidermal Pun-PGP-9 expression protected against moxidectin regardless of PP and against ivermectin only in the absence of active drug ingestion. Our results demonstrate the role of active drug ingestion by nematodes for susceptibility and provide functional evidence for the contribution of P-glycoproteins to ML resistance in a tissue-specific manner.

Curcumin ameliorates duodenal toxicity of AFB1 in chicken through inducing P-glycoprotein and downregulating cytochrome P450 enzymes

It has been reported that oral intake of aflatoxin B1 (AFB1)-contaminated feed could cause acute, sub-chronic, or chronic toxicity in livestock and poultry. However, the harmful effect of AFB1 on the small intestine is still controversial. Therefore, blocking the entry of AFB1 into the body through the digestive tract is one of the important methods to prevent its toxicity. In the present study, 1-day-old Arbor Acres broilers were randomly divided into 6 groups including control group, curcumin control group (450 mg curcumin/kg feed), curcumin low-, medium-, and high-dose group (150, 300, and 450 mg curcumin/kg feed + 5 mg AFB1/kg feed), and AFB1 group (5 mg AFB1/kg feed). After 28 d, the samples of chickens' duodenums were collected for further analyses. AFB1 caused abnormal functional and morphological changes in the duodenum, including histological lesions, increased the length of the duodenum and depth of crypt, decreased the unit weight of the duodenum, height of villus, and the value of villus height/crypt depth. Meanwhile, AFB1 administration enhanced malonaldehyde activity, 8-HOdG level, and the mRNA expression of cytochrome P450 (CYP450) enzymes, and reduced superoxide dismutase, catalase, adenosine triphosphatase (ATPase) activity and the mRNA expression of Abcb1. Importantly, curcumin supplementation partially ameliorated AFB1-induced abnormal functional and morphological signs of the duodenum, alleviated AFB1-induced oxidative stress, and decreased the mRNA expression of CYP450 enzymes. Furthermore, curcumin ameliorated AFB1-induced decrease in the Abcb1 mRNA expression, P-glycoprotein (P-gp) level, and ATPase activities. It has been suggested from these results that curcumin supplementation in the feed could ameliorate AFB1-induced duodenal toxicity and damage through downregulating CYP450 enzymes, promoting ATPase activities, and inducing P-gp in chickens.

Caenorhabditis elegans in anthelmintic research - Old model, new perspectives

For more than four decades, the free-living nematode Caenorhabditis elegans has been extensively used in anthelmintic research. Classic genetic screens and heterologous expression in the C. elegans model enormously contributed to the identification and characterization of molecular targets of all major anthelmintic drug classes. Although these findings provided substantial insights into common anthelmintic mechanisms, a breakthrough in the treatment and control of parasitic nematodes is still not in sight. Instead, we are facing increasing evidence that the enormous diversity within the phylum Nematoda cannot be recapitulated by any single free-living or parasitic species and the development of novel broad-spectrum anthelmintics is not be a simple goal. In the present review, we summarize certain milestones and challenges of the C. elegans model with focus on drug target identification, anthelmintic drug discovery and identification of resistance mechanisms. Furthermore, we present new perspectives and strategies on how current progress in C. elegans research will support future anthelmintic research.

Sub-lethal doses of albendazole induce drug metabolizing enzymes and increase albendazole deactivation in Haemonchus contortus adults

The efficacy of anthelmintic therapy of farm animals rapidly decreases due to drug resistance development in helminths. In resistant isolates, the increased expression and activity of drug-metabolizing enzymes (DMEs), e.g. cytochromes P450 (CYPs), UDP-glycosyltransferases (UGTs) and P-glycoprotein transporters (P-gps), in comparison to sensitive isolates have been described. However, the mechanisms and circumstances of DMEs induction are not well known. Therefore, the present study was designed to find the changes in expression of CYPs, UGTs and P-gps in adult parasitic nematodes Haemonchus contortus exposed to sub-lethal doses of the benzimidazole anthelmintic drug albendazole (ABZ) and its active metabolite ABZ-sulfoxide (ABZSO). In addition, the effect of ABZ at sub-lethal doses on the ability to deactivate ABZ during consequent treatment was studied. The results showed that contact of H. contortus adults with sub-lethal doses of ABZ and ABZSO led to a significant induction of several DMEs, particularly cyp-2, cyp-3, cyp-6, cyp-7, cyp-8, UGT10B1, UGT24C1, UGT26A2, UGT365A1, UGT366C1, UGT368B2, UGT367A1, UGT371A1, UGT372A1 and pgp-3, pgp-9.1, pgp-9.2, pgp-10. This induction led to increased formation of ABZ metabolites (especially glycosides) and their increased export from the helminths' body into the medium. The present study demonstrates for the first time that contact of H. contortus with sub-lethal doses of ABZ (e.g. during underdose treatment) improves the ability of H. contortus adults to deactivate ABZ in consequent therapy.

Differential ABC transporter gene expression in adult Dirofilaria immitis males and females following in vitro treatment with ivermectin, doxycycline or a combination of both

Background

Combination doxycycline/macrocyclic lactone (ML) protocols have been shown to provide a more rapid adulticidal and microfilaricidal effect than either MLs or doxycycline alone, although female worms were reported to have a higher tolerance to treatments compared to male worms. The present study aimed to evaluate how ABC transporters may be involved in the synergic effect of the combination treatment. Adult worms of D. immitis were treated in vitro for 24 hours with doxycycline (DOXY), ivermectin (IVM) and a combination of both, and changes in the modulation of ABC transporter genes were measured. Levels of doxycycline inside different treatment media, post-treatment, were determined through HPLC analysis.

Results

Quantitative RT-PCR analysis showed the presence of changes in the modulation of ABC transporter genes evaluated in this study. In particular, in female worms, the combination treatment induced a substantial increase in gene expressions, especially of Dim-pgp-10 and Dim-haf-4; whereas in male worms, the greatest increase in gene expression was observed for Dim-pgp-10 and Dim-pgp-11 when treated with DMSO + IVM and DMSO + DOXY/IVM. HPLC analysis of the DOXY concentrations in the media after in vitro treatments of male worms showed a slight difference between the DMSO + DOXY samples and the combination (DMSO + DOXY + IVM), while no difference was observed among females.

Conclusions

Further studies are required to explain whether the modulation of cellular efflux plays a role, even partially, in the adulticide effect of doxycycline/macrocyclic lactone combinations in heartworm-infected dogs. To the authors’ knowledge, this is the first study to evaluate P-gp expression in adult D. immitis.

Ivermectin reverses the drug resistance in cancer cells through EGFR/ERK/Akt/NF-κB pathway

Background

Discovery and development of novel drugs that are capable of overcoming drug resistance in tumor cells are urgently needed clinically. In this study, we sought to explore whether ivermectin (IVM), a macrolide antiparasitic agent, could overcome the resistance of cancer cells to the therapeutic drugs.

Methods

We used two solid tumor cell lines (HCT-8 colorectal cancer cells and MCF-7 breast cancer cells) and one hematologic tumor cell line (K562 chronic myeloid leukemia cells), which are resistant to the chemotherapeutic drugs vincristine and adriamycin respectively, and two xenograft mice models, including the solid tumor model in nude mice with the resistant HCT-8 cells and the leukemia model in NOD/SCID mice with the resistant K562 cells to investigate the reversal effect of IVM on the resistance in vitro and in vivo. MTT assay was used to investigate the effect of IVM on cancer cells growth in vitro. Flow cytometry, immunohistochemistry, and immunofluorescence were performed to investigate the reversal effect of IVM in vivo. Western blotting, qPCR, luciferase reporter assay and ChIP assay were used to detect the molecular mechanism of the reversal effect. Octet RED96 system and Co-IP were used to determine the interactions between IVM and EGFR.

Results

Our results indicated that ivermectin at its very low dose, which did not induce obvious cytotoxicity, drastically reversed the resistance of the tumor cells to the chemotherapeutic drugs both in vitro and in vivo. Mechanistically, ivermectin reversed the resistance mainly by reducing the expression of P-glycoprotein (P-gp) via inhibiting the epidermal growth factor receptor (EGFR), not by directly inhibiting P-gp activity. Ivermectin bound with the extracellular domain of EGFR, which inhibited the activation of EGFR and its downstream signaling cascade ERK/Akt/NF-κB. The inhibition of the transcriptional factor NF-κB led to the reduced P-gp transcription.

Conclusions

These findings demonstrated that ivermectin significantly enhanced the anti-cancer efficacy of chemotherapeutic drugs to tumor cells, especially in the drug-resistant cells. Thus, ivermectin, a FDA-approved antiparasitic drug, could potentially be used in combination with chemotherapeutic agents to treat cancers and in particular, the drug-resistant cancers.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1251-7) contains supplementary material, which is available to authorized users.

Inhibitory Effect of Berberine on Broiler P-glycoprotein Expression and Function: In Situ and In Vitro Studies

Overcoming P-glycoprotein (P-gp) efflux is a strategy to improve the absorption and pharmacokinetics of its substrate drugs. Berberine inhibits P-gp and thereby increases the bioavailability of the P-gp substrate digoxin in rodents. However, the effects of berberine on P-gp in chickens are still unclear. Here, we studied the role of berberine in modulating broilers P-gp expression and function through both in situ and in vitro models. In addition, molecular docking was applied to analyze the interactions of berberine with P-gp as well as with chicken xenobiotic receptor (CXR). The results showed that the mRNA expression levels of chicken P-gp and CXR decreased in the ileum following exposure to berberine. The absorption rate constant of rhodamine 123 increased after berberine treatment, as detected using an in situ single-pass intestinal perfusion model. Efflux ratios of P-gp substrates (tilmicosin, ciprofloxacin, clindamycin, ampicillin, and enrofloxacin) decreased and the apparent permeability coefficients increased after co-incubation with berberine in MDCK-chAbcb1 cell models. Bidirectional assay results showed that berberine could be transported by chicken P-gp with a transport ratio of 4.20, and this was attenuated by verapamil (an inhibitor of P-gp), which resulted in a ratio of 1.13. Molecular docking revealed that berberine could form favorable interactions with the binding pockets of both CXR and P-gp, with docking scores of −7.8 and −9.5 kcal/mol, respectively. These results indicate that berberine is a substrate of chicken P-gp and down-regulates P-gp expression in chicken tissues, thereby increasing the absorption of P-gp substrates. Our findings suggest that berberine increases the bioavailability of other drugs and that drug-drug interactions should be considered when it is co-administered with other P-gp substrates with narrow therapeutic windows.

Minimal modulation of macrocyclic lactone susceptibility in Caenorhabditis elegans following inhibition of cytochrome P450 monooxygenase activity

Anthelmintic and in particular macrocyclic lactone (ML) resistance is a widespread problem in trichostrongyloid parasitic nematodes, yet mechanisms of ML resistance are still poorly understood. In the absence of target-site changes in resistant parasite field populations, increased drug extrusion and xenobiotic metabolism have been implicated in modification of susceptibility to MLs. In addition to P-glycoproteins, cytochrome P450 monooxygenases (CYPs) were considered to be involved in ML resistance. CYPs are highly divergent in nematodes with about 80 genes in the model organism Caenorhabditis elegans. Using larval development assays in the C. elegans model, piperonyl butoxide (PBO) and a temperature-sensitive variant of the emb-8 cytochrome reductase were used for chemical and genetic ablation of CYP activity. Additionally, a loss-of-function variant of cyp-14A5 was characterized to determine whether increased expression of this CYP in an ivermectin (IVM)-tolerant C. elegans line might be related to the phenotype. In a preliminary experiment with PBO, susceptibility to 5 nM IVM was synergistically increased by PBO. However, effects of genetic ablation of CYP activity on the EC₅₀ values were small (1.5-fold decrease) for IVM and not significant for moxidectin (MOX). However, due to the steep concentration-response-curves, there were again strong differences between the wild-type and the CYP deficient genotype at individual IVM but not MOX concentrations. Although these results suggest small but significant effects on the susceptibility level of C. elegans to IVM, the cyp14A5 gene proposed by a previous study as candidate was ruled out since it was neither IVM/MOX inducible nor did a strain with a loss-of-function allele show increased susceptibility to either drug. In conclusion, the effect of the CYP system on IVM susceptibility in C. elegans is at best low while effects on MOX susceptibility were not detected. The previously suggested candidate cyp14A5 could be excluded to be involved in ML metabolism.

Highlights on the Application of Genomics and Bioinformatics in the Fight Against Infectious Diseases: Challenges and Opportunities in Africa

Genomics and bioinformatics are increasingly contributing to our understanding of infectious diseases caused by bacterial pathogens such as Mycobacterium tuberculosis and parasites such as Plasmodium falciparum. This ranges from investigations of disease outbreaks and pathogenesis, host and pathogen genomic variation, and host immune evasion mechanisms to identification of potential diagnostic markers and vaccine targets. High throughput genomics data generated from pathogens and animal models can be combined with host genomics and patients’ health records to give advice on treatment options as well as potential drug and vaccine interactions. However, despite accounting for the highest burden of infectious diseases, Africa has the lowest research output on infectious disease genomics. Here we review the contributions of genomics and bioinformatics to the management of infectious diseases of serious public health concern in Africa including tuberculosis (TB), dengue fever, malaria and filariasis. Furthermore, we discuss how genomics and bioinformatics can be applied to identify drug and vaccine targets. We conclude by identifying challenges to genomics research in Africa and highlighting how these can be overcome where possible.

Using the lentiviral vector system to stably express chicken P-gp and BCRP in MDCK cells for screening the substrates and studying the interplay of both transporters

Transporters P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) are known to influence the pharmacokinetics and toxicity of substrate drugs. However, no detailed information is as yet available about functional activity and substrate spectra of chicken P-gp and BCRP. In this study, BCRP single and BCRP/P-gp double-transfected MDCK cell lines (named MDCK-chAbcg2 and MDCK-chAbcg2/Abcb1, respectively) were generated using lentiviral vector system to develop reliable systems for screening the substrates for these two transporters and study the interplay between them. The constructed cell lines significantly expressed functional exogenous proteins and expression persisted for at least 50 generations with no decrease. Enrofloxacin, ciprofloxacin, tilmicosin, sulfadiazine, ampicillin and clindamycin were classified as the substrates of chicken P-gp according to the rules suggested by FDA, as their net efflux ratios were greater than two. Similarly, enrofloxacin, ciprofloxacin, tilmicosin, florfenicol, ampicillin and clindamycin were classified as the substrates of BCRP. Among these drugs, enrofloxacin, ciprofloxacin, tilmicosin, ampicillin, and clindamycin were the cosubstrates of P-gp and BCRP, however, chicken BCRP and P-gp exhibit different affinities to the shared substrates at different concentrations by blocking either one or both transport with specific inhibitors in the coexpression system. It was also found that ceftiofur, amoxicillin and doxycycline were not substrates of either chicken BCRP or the substrates of chicken P-gp. These constructed cell models provide useful systems for high-throughput screening of the potential substrates of chicken BCRP and P-gp as well as the drug-drug interaction mediated via chicken BCRP and P-gp.