Dominican University of California
 

All Conference Presentations, Performances and Exhibits

Location

Guzman 113

Start Date

4-15-2016 4:35 PM

End Date

4-15-2016 5:00 PM

Department

Natural Sciences and Mathematics

Student Type

Undergraduate - Honors

Faculty Mentor

Roland Cooper, Ph.D.

Presentation Format

Oral Presentation

Abstract/Description

Plasmodium falciparum, a protozoan parasite known as malaria, widely impacts human health; thus antimalarial drug investigations are critical. Doxycycline is a commonly used antimalarial prophylactic, but its mechanism of action is unclear. In prokaryotes, doxycycline works as an antibacterial by disrupting protein translation via the small subunit ribosome. Interestingly, P. falciparum has a small subunit ribosome of prokaryotic origins in the apicoplast, a plastid-like organelle. Therefore, we hypothesized that doxycycline works in P. falciparum by inhibiting protein synthesis via the small subunit ribosomal RNA and that mutations in the gene encoding the P. falciparum apicoplast small subunit ribosomal RNA (pfSSrRNA) are associated with doxycycline resistance. We generated nine doxycycline-resistant parasite lines with continuous incremental drug pressure over approximately twelve months. Resistant lines had doxycycline IC50 values of ~2.4 μM while the drug-free control had an IC50 of 587 nM, resulting in a ~4 fold decrease in doxycycline susceptibility as measured by 96-hour growth inhibition assays. Sequencing of the pfssrRNA gene in a resistant line revealed a g439a single nucleotide polymorphism (SNP). We suspect this mutation reduces parasite susceptibility to doxycycline by altering the molecular structure of the apicoplast SSrRNA, so that doxycycline can no longer inhibit protein synthesis. Future studies involve cloning the resistant lines, sequencing pfssrRNA for all resistant lines, and characterizing the drug phenotypes of the resistant lines to doxycycline and a panel of standard antimalarial drugs. Understanding how doxycycline works will help health care professionals better combat doxycycline resistance in the field.

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Apr 15th, 4:35 PM Apr 15th, 5:00 PM

Doxycycline Resistance in Plasmodium falciparum Linked to Single Nucleotide Polymorphisms in the Plasmodium falciparum apicoplast Small Subunit Ribosomal RNA (pfSSrRNA) gene

Guzman 113

Plasmodium falciparum, a protozoan parasite known as malaria, widely impacts human health; thus antimalarial drug investigations are critical. Doxycycline is a commonly used antimalarial prophylactic, but its mechanism of action is unclear. In prokaryotes, doxycycline works as an antibacterial by disrupting protein translation via the small subunit ribosome. Interestingly, P. falciparum has a small subunit ribosome of prokaryotic origins in the apicoplast, a plastid-like organelle. Therefore, we hypothesized that doxycycline works in P. falciparum by inhibiting protein synthesis via the small subunit ribosomal RNA and that mutations in the gene encoding the P. falciparum apicoplast small subunit ribosomal RNA (pfSSrRNA) are associated with doxycycline resistance. We generated nine doxycycline-resistant parasite lines with continuous incremental drug pressure over approximately twelve months. Resistant lines had doxycycline IC50 values of ~2.4 μM while the drug-free control had an IC50 of 587 nM, resulting in a ~4 fold decrease in doxycycline susceptibility as measured by 96-hour growth inhibition assays. Sequencing of the pfssrRNA gene in a resistant line revealed a g439a single nucleotide polymorphism (SNP). We suspect this mutation reduces parasite susceptibility to doxycycline by altering the molecular structure of the apicoplast SSrRNA, so that doxycycline can no longer inhibit protein synthesis. Future studies involve cloning the resistant lines, sequencing pfssrRNA for all resistant lines, and characterizing the drug phenotypes of the resistant lines to doxycycline and a panel of standard antimalarial drugs. Understanding how doxycycline works will help health care professionals better combat doxycycline resistance in the field.