scholarly journals Quantitative benzimidazole resistance and fitness effects of parasitic nematode beta-tubulin alleles

2020 ◽  
Vol 14 ◽  
pp. 28-36 ◽  
Author(s):  
Clayton M. Dilks ◽  
Steffen R. Hahnel ◽  
Qicong Sheng ◽  
Lijiang Long ◽  
Patrick T. McGrath ◽  
...  
Keyword(s):  
Parasitic Nematode ◽  
Beta Tubulin ◽  
Fitness Effects ◽  
Benzimidazole Resistance

scholarly journals Quantitative benzimidazole resistance and fitness effects of parasitic nematode beta-tubulin alleles

2020 ◽  
Author(s):  
Clayton M. Dilks ◽  
Steffen R. Hahnel ◽  
Qicong Sheng ◽  
Lijiang Long ◽  
Patrick T. McGrath ◽  
...  
Keyword(s):  
Genetic Background ◽  
Molecular Mechanisms ◽  
Parasitic Nematode ◽  
Animal Health ◽  
List Type ◽  
Tubulin Gene ◽  
Beta Tubulin ◽  
Competitive Fitness ◽  
Benzimidazole Resistance ◽  
Beta Tubulin Gene

AbstractInfections by parasitic nematodes inflict a huge burden on the health of humans and livestock throughout the world. Anthelmintic drugs are the first line of defense against these infections. Unfortunately, resistance to these drugs is rampant and continues to spread. To improve treatment strategies, we must understand the genetics and molecular mechanisms that underlie resistance. Studies of the fungus Aspergillus nidulans and the free-living nematode Caenorhabditis elegans discovered that a beta-tubulin gene is mutated in benzimidazole (BZ) resistant strains. In parasitic nematode populations, three canonical beta-tubulin alleles, F200Y, E198A, and F167Y, have long been correlated with resistance. Additionally, improvements in sequencing technologies have identified new alleles - E198V, E198L, E198K, E198I, and E198Stop - also correlated with BZ resistance. However, none of these alleles have been proven to cause resistance. To empirically demonstrate this point, we independently introduced the three canonical alleles as well as two of the newly identified alleles, E198V and E198L, into the BZ susceptible C. elegans N2 genetic background. These genome-edited strains were exposed to both albendazole and fenbendazole to quantitatively measure animal responses to BZs. We used a range of doses for each BZ compound to define response curves and found that all five of the alleles conferred resistance to BZ compounds equal to a loss of the entire beta-tubulin gene. These results prove that the parasite beta-tubulin alleles cause resistance. The E198V allele is found at low frequencies in natural parasite populations, suggesting that it could affect fitness. We performed competitive fitness assays and demonstrated that the E198V allele reduces animal health, supporting the hypothesis that this allele is less fit in field populations. Overall, we present a powerful platform to quantitatively assess anthelmintic resistance and effects of specific resistance alleles on organismal fitness in the presence or absence of the drug.HighlightsAll three canonical parasitic nematode beta-tubulin alleles (F167Y, E198A, F200Y) and two newly identified alleles (E198V, E198L) confer equal levels of benzimidazole resistance in a defined genetic background using single-generation, high-replication drug response assays.Beta-tubulin variants are strongly selected in albendazole conditions in multigenerational competitive fitness assays, but these alleles confer different levels of benzimidazole resistance over time.Only the E198V allele confers a fitness cost in control (non-benzimidazole) conditions as compared to all other tested beta-tubulin alleles, suggesting that this intermediate allele might only be found in field populations at low frequency because it causes reduced fitness.Graphical Abstract

Genotypic profile of benzimidazole resistance associated with SNP F167Y in the beta-tubulin gene of Necator americanus helminths obtained from Brazilian populations

2020 ◽  
Vol 86 ◽  
pp. 104594
Author(s):  
Luis Fernando Viana Furtado ◽  
Talita Rodrigues dos Santos ◽  
Valéria Nayara Gomes Mendes de Oliveira ◽  
Élida Mara Leite Rabelo
Keyword(s):  
Tubulin Gene ◽  
Beta Tubulin ◽  
Necator Americanus ◽  
Benzimidazole Resistance ◽  
Genotypic Profile ◽  
Beta Tubulin Gene ◽  
Brazilian Populations

Genotypic profile of benzimidazole resistance associated with SNP F167Y and F200Y beta-tubulin gene in Brazilian populations of Haemonchus contortus of goats

2017 ◽  
Vol 8 ◽  
pp. 28-34 ◽  
Author(s):  
Sabrina Mota Lambert ◽  
Sandra Mayumi Nishi ◽  
Lívia Ribeiro Mendonça ◽  
Bárbara Maria Paraná da Silva Souza ◽  
Fred da Silva Julião ◽  
...  
Keyword(s):  
Haemonchus Contortus ◽  
Tubulin Gene ◽  
Beta Tubulin ◽  
Benzimidazole Resistance ◽  
Genotypic Profile ◽  
Beta Tubulin Gene ◽  
Brazilian Populations

scholarly journals First identification of the benzimidazole resistance-associated F200Y SNP in the beta-tubulin gene in Ascaris lumbricoides

PLoS ONE ◽  
2019 ◽  
Vol 14 (10) ◽  
pp. e0224108 ◽  
Author(s):  
Luis Fernando Viana Furtado ◽  
Celi da Silva Medeiros ◽  
Luciana Werneck Zuccherato ◽  
William Pereira Alves ◽  
Valéria Nayara Gomes Mendes de Oliveira ◽  
...  
Keyword(s):  
Ascaris Lumbricoides ◽  
Tubulin Gene ◽  
Beta Tubulin ◽  
Benzimidazole Resistance ◽  
Beta Tubulin Gene

Monitoring benzimidazole resistance in Phyllosticta citricarpa using a molecular assay targeting mutations in codons 198 and 200 of the beta-tubulin gene

Plant Disease ◽  
2021 ◽  
Author(s):  
Providence Moyo ◽  
Glynnis Cook ◽  
Elaine Basson ◽  
Chanel Steyn ◽  
Rachelle Bester ◽  
...  
Keyword(s):  
Amino Acid ◽  
Fungal Pathogens ◽  
Molecular Mechanisms ◽  
Management Practices ◽  
Black Spot ◽  
Tubulin Gene ◽  
Beta Tubulin ◽  
Benzimidazole Resistance ◽  
Phyllosticta Citricarpa ◽  
Beta Tubulin Gene

Citrus black spot (CBS), caused by Phyllosticta citricarpa, is an economically important disease, which is effectively controlled by repeated fungicide applications to protect fruit from infection. Systemic fungicides such as benzimidazoles are widely used for controlling CBS in South Africa, but the molecular mechanisms of benzimidazole resistance in P. citricarpa had not been investigated. Analysis of the nucleotide sequence of the beta-tubulin gene in P. citricarpa revealed mutations inducing three amino acid replacements in benzimidazole-resistant isolates when compared to that of sensitive strains. Amino acid replacements in benzimidazole-resistant isolates included the change of glutamic acid to either alanine or lysine at codon 198 of the beta-tubulin gene and the change from phenylalanine to tyrosine at codon 200. All three mutations were previously implicated in benzimidazole resistance in several fungal pathogens. A polymerase chain reaction (PCR) assay was designed to amplify a portion of the beta-tubulin gene, which is subsequently sequenced to identify benzimidazole resistance in P. citricarpa. This PCR and sequence assay was found to be a more rapid and reliable method for detecting resistance compared to the fungicide-amended plate tests and is valuable for monitoring the occurrence of benzimidazole-resistant P. citricarpa and for assessment of the need for alternative CBS management practices.

scholarly journals Genetic variability of the beta-tubulin genes in benzimidazole-susceptible and -resistant strains of Haemonchus contortus.

Genetics ◽  
1994 ◽  
Vol 138 (1) ◽  
pp. 103-110 ◽  
Author(s):  
R N Beech ◽  
R K Prichard ◽  
M E Scott
Keyword(s):  
Haemonchus Contortus ◽  
Allelic Variation ◽  
Selection Process ◽  
Chemotherapeutic Agents ◽  
Susceptible Strain ◽  
Farm Animals ◽  
Beta Tubulin ◽  
Tubulin Genes ◽  
Benzimidazole Resistance ◽  
Resistant Strains

Abstract Benzimidazole anthelmintics are the most common chemotherapeutic agents used to remove intestinal helminths from farm animals. The development of drug resistance within helminth populations is wide-spread and can render these drugs essentially useless. The mechanism of benzimidazole resistance appears to be common to many species ranging from fungi to nematodes and involves alterations in the genes encoding beta-tubulin. During the selection process resulting in resistance, there must be quantitative changes in the population gene pool. Knowledge of these changes would indicate the mechanisms underlying the spread of resistance in the population, which in turn could be used to design more effective drug administration strategies. To this end we have identified allelic variation at two beta-tubulin genes in Haemonchus contortus using restriction map analysis of individual adults. Extremely high levels of variation were identified at both loci within a susceptible strain. In two independently derived benzimidazole resistant strains, allele frequencies at both loci were significantly different from the susceptible strain but not from each other. The same alleles at both loci, in both resistant strains, were favored by selection with benzimidazoles, suggesting that both loci are involved in determining benzimidazole resistance. These data confirm that changes in allele frequency, rather than novel genetic rearrangements induced by exposure to the drug, explain the changes associated with benzimidazole resistance. These results also show that any DNA based test for the development of benzimidazole resistance must take into account the frequency of alleles present in the population and not simply test for the presence or absence of specific allelic types.

scholarly journals Newly identified parasitic nematode beta-tubulin alleles confer resistance to benzimidazoles

2021 ◽  
Author(s):  
Clayton Dilks ◽  
Emily Koury ◽  
Claire Buchanan ◽  
Erik Andersen
Keyword(s):  
Parasitic Nematode ◽  
Parasitic Nematodes ◽  
Beta Tubulin ◽  
Resistance Phenotype ◽  
C Elegans ◽  
Fitness Consequences ◽  
Parasite Populations ◽  
Seven Generations ◽  
New Alleles ◽  
Anthelmintic Drugs

Infections by parasitic nematodes cause large health and economic burdens worldwide. We use anthelmintic drugs to reduce these infections. However, resistance to anthelmintic drugs is extremely common and increasing worldwide. It is essential to understand the mechanisms of resistance to slow its spread. Recently, four new parasitic nematode beta-tubulin alleles have been identified in benzimidazole (BZ) resistant parasite populations: E198I, E198K, E198T, and E198stop. These alleles have not been tested for the ability to confer resistance or for any effects that they might have on organismal fitness. We introduced these four new alleles into the sensitive C. elegans laboratory-adapted N2 strain and exposed these genome-edited strains to both albendazole and fenbendazole. We found that all four alleles conferred resistance to both BZ drugs. Additionally, we tested for fitness consequences in both control and albendazole conditions over seven generations in competitive fitness assays. We found that none of the edited alleles had deleterious effects on fitness in control conditions and that all four alleles conferred strong and equivalent fitness benefits in BZ drug conditions. Because it is unknown if previously validated alleles confer a dominant or recessive BZ resistance phenotype, we tested the phenotypes caused by five of these alleles and found that none of them conferred a dominant BZ resistance phenotype. Accurate measurements of resistance, fitness effects, and dominance caused by the resistance alleles allow for the generation of better models of population dynamics and facilitate control practices that maximize the efficacy of this critical anthelmintic drug class.

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