Basic Antimicrobial Pharmacology
Dr. Matthias Götte Department of Medical Microbiology & Immunology Faculty of Medicine & Dentistry University of Alberta
Email: [email protected] Date: September 15, 2020 Presenter Disclosure
MG received funding from Gilead Sciences Inc. for mechanistic studies on Remdesivir.
Lecture Title: Date: Learning Objectives
Provide a basic understanding of structure and mechanisms of antivirals and antibiotics Provide a basic understanding of mechanisms associated with antimicrobial resistance (AMR) Discuss therapeutic approaches designed to overcome AMR
Lecture Title: Date: Alignment with Learning Outcomes
Complex contributing factors to antimicrobial use and the emergence and spread of AMR: a biochemical perspective
Lecture Title: Date: Matthias Götte, PhD MSc Chemistry Professor and Chair PhD Biochemistry Department of Medical Microbiology & Immunology University of Alberta
HIV/HCV Lab 2000-2014 Emerging Pathogens 2014 - present Emerging Viruses
SOURCE: Bean et al., 2013. Ebola Outbreaks 2014 and 2018 The novel coronavirus SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2) is the causative agent of COVID-19, first reported in December 2019.
WHO declares in March 2020 a pandemic. Emerging Bacteria Microorganisms and Pathogens
https://ib.bioninja.com.au/ Human Immunodeficiency Virus (HIV) The 10 Leading Causes of Death in the US (1950 – 2000)
Strauss & Strauss 2008 ”Triple Therapy”
Strauss & Strauss 2008 Viral Polymerases are Good Targets for Antiviral Drugs
Fingers Thumb
Palm
HIV-1 Reverse Transcriptase How do they function?
Castro et al., 2009; Nature Structural Biology AZT: the 1st HIV drug
https://www.researchgate.net/figure/Mechani sm-of-antiviral-action-of-AZT
Different Nucleoside Analogue RT Inhibitors (NRTIs)
Thymidine AZT O d4T O O CH CH 3 HN 3 CH HN HN 3 O N O N Ho O O N Ho O Ho O
OH N3
Cytidine Chain-termination
NH2 3TC NH 2 P N N B P A O N O N P Ho O Ho O P P P H OH
S OH P P P P P Resistance To Antiviral Drugs HIV exists as a mixture of billions of different particles in infected patients.
Why? HIV and other viruses are sloppy and make mistakes during replication.
Why is this important? Some of these viruses are resistant to antiviral drugs. Selection of Resistant Viruses on Treatment HIV Levels Before Treatment HIV Levels on Treatment Take Your Medication to Keep Drug Levels Sufficiently High Monotherapy Fails
“Orange drugs” don’t work against resistant variants.
Triple Therapy Works
All three drugs are more effective and suppress the emergence of resistant variants. AND “white and yellow drugs” still work against resistant variants. Why is the drug not working anymore? Resistant variants contain mutations that change the interaction with the drug.
Drug Drug
Drug Binding Altered Pocket Site Reduces Binding Approved Anti-HIV Drugs
Drug Classes Monotherapy 1-2
Initiation of Triple Therapy 3-4
Switch to Novel Drug 5 Classes if Necessary SARS-CoV-2 and COVID-19 Life Cycle of SARS-CoV-2: Looking for Potential Targets
Eastman et al. 2020, ACS Cent Sci Discovery of Remdesivir (GS-5734)
Screening Prodrug design Gilead library of (CDC) (Gilead) nucleosides and nucleotides Profiling (USAMRIID, GS-441524 CDC) GS-5734 (Remdesivir)
Source: Gilead Sciences Inc. Warren et al, Nature, 2016 Intracellular Metabolic Pathway
GS-5734 GS-441524
Protide by-passes Nucleotidase Hydrolase rate limiting first Slow First phosphorylation Phosphorylation
Phosphoramidase Nucleotide Kinases
Nucleotide Active Nucleotide Alanine-Metabolite Monophosphate Triphosphate Resistance to Remdesivir ? In Vitro Selection in the Mouse Hepatitis Virus
Agostini et al. 2018, mBio
Remdesivir is a “Delayed Cain-Terminator”
Steric Clash with S861 and Remdesivir
Antibiotics Alexander Fleming discovered Penicillin in 1928 (Nobel Prize in 1945)
He noticed that bacteria do not grow near fungus. Though this experiment was not planned, he discovered that the fungus produces a “mold juice” later referred to as penicillin…
Lactams Inhibit Cell Wall Synthesis https://basicmedicalkey.com/chemotherapy-of-tuberculosis-mycobacterium-avium-complex-disease-and-leprosy/ Fleming and Antibiotic Resistance
Fleming discovered that bacteria developed antibiotic resistance whenever too little penicillin was used or when it was used for too short a period.
He warned in 1945: “The time may come when penicillin can be bought by anyone in the shops. Then there is the danger that the ignorant man may easily underdose himself and by exposing his microbes to non-lethal quantities of the drug make them resistant.” UK Economist Jim O’Neill et al. 2014
https://www.gov.uk/.../health-matters-antimicrobial-resistance https://www.gov.uk/.../health-matters-antimicrobial-resistance https://www.canada.ca…preserving-antibiotics/about-antibiotic- resistance.html From AMR Spread between Bacteria…
Barton et al. 2007. Evolution. Mechanisms of Antibiotic Resistance
https://www.reactgroup.org Focus on Inactivating Enzymes
Beta-Lactamase Enzymes Alternative Treatments: Phage Therapy
Phages Are Viruses that Infect Bacteria
Salmond, G. P. & Fineran, P. C. Nat. Rev. Microbiol. 13,777–786 (2015). 1Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA. 2Great Ormond Street Hospital, London, UK. 3Department of Medicine, University of California, San Diego, La Jolla, CA, USA. 4These authors contributed equally: Rebekah M. Dedrick and Carlos A. Guerrero- Bustamante. *e-mail: [email protected]; [email protected] Nature Medicine | 730 VOL 25 | MAY 2019 | 730–733 | www.nature.com/naturemedicine Triple Therapy Killed Antibiotic Resistant Bacteria
A 15-year-old patient with cystic fibrosis and a life-threatening bacterial infection was treated with a three-phage cocktail following lung transplantation. Lytic phage derivatives efficiently killed the infectious.
Phage treatment was associated with clinical improvement, although the athors cannot exclude the possibility that patient gains would have occurred without phage treatment. Summary
Nucleoside analogues are frequently used antivirals These compounds target the viral polymerase and interfere with genome replication Resistance is selected from a pool of diverse viruses Lactams are frequently used antibiotics These compounds interfere with cell wall synthesis Selection of resistance in bacteria is often based on similar principles as reported for viruses
Lecture Title: Date: Discussion Questions
Describe important principles underlying the selection of resistance in viruses and bacteria, respectively.
What is a fundamentally different mechanism that is used by Bacteria?
Non-adherence to antimicrobial drug regimens can lead to the development of resistance. Why?
A combination of antivirals or antibiotics can prevent the emergence of resistance. Why?
Lecture Title: Date: Thank You!
Dr. Matthias Götte Department of Medical Microbiology & Immunology Faculty of Medicine & Dentistry University of Alberta
Email: [email protected]
Lecture Title: Date: