Genetic diversity in the metronidazole metabolism genes nitroreductases and pyruvate ferredoxin oxidoreductases in susceptible and refractory clinical samples of Giardia lamblia
The effectiveness of metronidazole against the tetraploid intestinal parasite Giardia lamblia is dependent on its activation/inactivation within the cytoplasm. There are several activating enzymes, including pyruvate ferredoxin reductase (PFOR) and nitroreductase (NR) 1 which metabolize metronidazol...
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Elsevier
2023-04-01
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| Series: | International Journal for Parasitology: Drugs and Drug Resistance |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2211320722000367 |
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| author | Christina S. Saghaug Astrid L. Gamlem Kirsti B. Hauge Juha Vahokoski Christian Klotz Toni Aebischer Nina Langeland Kurt Hanevik |
| author_facet | Christina S. Saghaug Astrid L. Gamlem Kirsti B. Hauge Juha Vahokoski Christian Klotz Toni Aebischer Nina Langeland Kurt Hanevik |
| author_sort | Christina S. Saghaug |
| collection | DOAJ |
| description | The effectiveness of metronidazole against the tetraploid intestinal parasite Giardia lamblia is dependent on its activation/inactivation within the cytoplasm. There are several activating enzymes, including pyruvate ferredoxin reductase (PFOR) and nitroreductase (NR) 1 which metabolize metronidazole into toxic forms, while NR2 on the other hand inactivates it. Metronidazole treatment failures have been increasing rapidly over the last decade, indicating genetic resistance mechanisms. Analyzing genetic variation in the PFOR and NR genes in susceptible and refractory Giardia isolates may help identify potential markers of resistance.Full length PFOR1, PFOR2, NR1 and NR2 genes from clinical culturable isolates and non-cultured clinical Giardia assemblage B samples were cloned, sequenced and single nucleotide variants (SNVs) were analyzed to assess genetic diversity and alleles.A similar ratio of amino acid changing SNVs per gene length was found for the NRs; 4.2% for NR1 and 6.4% for NR2, while the PFOR1 and PFOR2 genes had less variability with a ratio of 1.1% and 1.6%, respectively. One of the samples from a refractory case had a nonsense mutation which caused a truncated NR1 gene in one out of six alleles. Further, we found three NR2 alleles with frameshift mutations, possibly causing a truncated protein in two susceptible isolates. One of these isolates was homozygous for the affected NR2 allele. Three nsSNVs with potential for affecting protein function were found in the ferredoxin domain of the PFOR2 gene. The considerable variation and discovery of mutations possibly causing dysfunctional NR proteins in clinical Giardia assemblage B isolates, reveal a potential for genetic link to metronidazole susceptibility and resistance. |
| first_indexed | 2024-04-09T20:20:43Z |
| format | Article |
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| institution | Directory Open Access Journal |
| issn | 2211-3207 |
| language | English |
| last_indexed | 2024-04-09T20:20:43Z |
| publishDate | 2023-04-01 |
| publisher | Elsevier |
| record_format | Article |
| series | International Journal for Parasitology: Drugs and Drug Resistance |
| spelling | doaj.art-3c00945d5be44fffa805e8ddfa90d28c2023-03-31T05:53:18ZengElsevierInternational Journal for Parasitology: Drugs and Drug Resistance2211-32072023-04-01215160Genetic diversity in the metronidazole metabolism genes nitroreductases and pyruvate ferredoxin oxidoreductases in susceptible and refractory clinical samples of Giardia lambliaChristina S. Saghaug0Astrid L. Gamlem1Kirsti B. Hauge2Juha Vahokoski3Christian Klotz4Toni Aebischer5Nina Langeland6Kurt Hanevik7Department of Clinical Science, University of Bergen, Bergen, Norway; Norwegian National Advisory Unit on Tropical Infectious Diseases, Department of Medicine, Haukeland University Hospital, Bergen, Norway; Corresponding author. University of Bergen, Department of Clinical Science, 8th floor, Lab-building, N-5021, Bergen, Norway.Department of Clinical Science, University of Bergen, Bergen, NorwayDepartment of Clinical Science, University of Bergen, Bergen, NorwayDepartment of Clinical Science, University of Bergen, Bergen, Norway; Department of Medicine, Haukeland University Hospital, Bergen, NorwayDepartment of Infectious Diseases, Unit 16 Mycotic and Parasitic Agents and Mycobacteria, Robert Koch-Institute, Berlin, GermanyDepartment of Infectious Diseases, Unit 16 Mycotic and Parasitic Agents and Mycobacteria, Robert Koch-Institute, Berlin, GermanyDepartment of Clinical Science, University of Bergen, Bergen, Norway; Norwegian National Advisory Unit on Tropical Infectious Diseases, Department of Medicine, Haukeland University Hospital, Bergen, NorwayDepartment of Clinical Science, University of Bergen, Bergen, Norway; Norwegian National Advisory Unit on Tropical Infectious Diseases, Department of Medicine, Haukeland University Hospital, Bergen, NorwayThe effectiveness of metronidazole against the tetraploid intestinal parasite Giardia lamblia is dependent on its activation/inactivation within the cytoplasm. There are several activating enzymes, including pyruvate ferredoxin reductase (PFOR) and nitroreductase (NR) 1 which metabolize metronidazole into toxic forms, while NR2 on the other hand inactivates it. Metronidazole treatment failures have been increasing rapidly over the last decade, indicating genetic resistance mechanisms. Analyzing genetic variation in the PFOR and NR genes in susceptible and refractory Giardia isolates may help identify potential markers of resistance.Full length PFOR1, PFOR2, NR1 and NR2 genes from clinical culturable isolates and non-cultured clinical Giardia assemblage B samples were cloned, sequenced and single nucleotide variants (SNVs) were analyzed to assess genetic diversity and alleles.A similar ratio of amino acid changing SNVs per gene length was found for the NRs; 4.2% for NR1 and 6.4% for NR2, while the PFOR1 and PFOR2 genes had less variability with a ratio of 1.1% and 1.6%, respectively. One of the samples from a refractory case had a nonsense mutation which caused a truncated NR1 gene in one out of six alleles. Further, we found three NR2 alleles with frameshift mutations, possibly causing a truncated protein in two susceptible isolates. One of these isolates was homozygous for the affected NR2 allele. Three nsSNVs with potential for affecting protein function were found in the ferredoxin domain of the PFOR2 gene. The considerable variation and discovery of mutations possibly causing dysfunctional NR proteins in clinical Giardia assemblage B isolates, reveal a potential for genetic link to metronidazole susceptibility and resistance.http://www.sciencedirect.com/science/article/pii/S2211320722000367NitroreductasePyruvate ferredoxin oxidoreductaseMetronidazoleGenetic diversityAlleleResistance |
| spellingShingle | Christina S. Saghaug Astrid L. Gamlem Kirsti B. Hauge Juha Vahokoski Christian Klotz Toni Aebischer Nina Langeland Kurt Hanevik Genetic diversity in the metronidazole metabolism genes nitroreductases and pyruvate ferredoxin oxidoreductases in susceptible and refractory clinical samples of Giardia lamblia International Journal for Parasitology: Drugs and Drug Resistance Nitroreductase Pyruvate ferredoxin oxidoreductase Metronidazole Genetic diversity Allele Resistance |
| title | Genetic diversity in the metronidazole metabolism genes nitroreductases and pyruvate ferredoxin oxidoreductases in susceptible and refractory clinical samples of Giardia lamblia |
| title_full | Genetic diversity in the metronidazole metabolism genes nitroreductases and pyruvate ferredoxin oxidoreductases in susceptible and refractory clinical samples of Giardia lamblia |
| title_fullStr | Genetic diversity in the metronidazole metabolism genes nitroreductases and pyruvate ferredoxin oxidoreductases in susceptible and refractory clinical samples of Giardia lamblia |
| title_full_unstemmed | Genetic diversity in the metronidazole metabolism genes nitroreductases and pyruvate ferredoxin oxidoreductases in susceptible and refractory clinical samples of Giardia lamblia |
| title_short | Genetic diversity in the metronidazole metabolism genes nitroreductases and pyruvate ferredoxin oxidoreductases in susceptible and refractory clinical samples of Giardia lamblia |
| title_sort | genetic diversity in the metronidazole metabolism genes nitroreductases and pyruvate ferredoxin oxidoreductases in susceptible and refractory clinical samples of giardia lamblia |
| topic | Nitroreductase Pyruvate ferredoxin oxidoreductase Metronidazole Genetic diversity Allele Resistance |
| url | http://www.sciencedirect.com/science/article/pii/S2211320722000367 |
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