Healed by a crocodile: The

search for new antibiotics.

TEDx GMU Monique van Hoek

Associate Professor

School of Systems Biology

George Mason University

We need new antibiotics.

Rampant Antibiotic Resistant Infections emerging globally.

Common infections becoming untreatable.

We need new antibiotics.

Very few new antibiotics in the drug development pipeline.

Entering the Dark Ages of antibiotic resistance.

We need new antibiotics.

Resurgence of “old” infections: Tuberculosis – a modern plague

Lest we forget… June of 1924 a young man

developed a blister on his toe while

playing tennis.

A week later he was dead from a

bacterial infection.

The young man was President

Calvin Coolidge's son.

When he heard the news, Coolidge

wept and asked what was "the

power and the glory of the

presidency" worth if he could not

prevent the death of his son from a

simple blister?

That is the world we are heading

back to… http://2.bp.blogspot.com/-

Uh_R1A3vO6M/TlBa_fUoNsI/AAAAAAAAEtg/dsx4BotDt_M/s400/004b13cea00423b3.j

pg

Calvin Jr., Calvin Sr., Grace, and John Coolidge, and their dog. This

photo was taken on the same day that Calvin Jr. got a blister while

playing tennis and later died from the infection.

• 4 y.o. girl in excellent health suddenly developed facial skin infection • Spread relentlessly, fever to 104F • Could not sleep because her face and neck so swollen she could not swallow

her own saliva • Began gasping for breath Herrell. 1943. Proc Staff Meetings Mayo Clinic 18:65-76

On arrival to the hospital

The “Dark Ages”

On arrival to the hospital

After 14 days of penicillin

“Moribund”

(on the verge of death)

Totally fine…

Antibiotics: A Global Resource

in Need of Protection

Prior generations of scientists gave us the gift of antibiotics

Today, we have to ensure this global treasure is available for our children and future generations.

Infectious Diseases Society of America campaign

Where can we find new antibiotics?

“Specific” immunity “Innate” immunity

Two types of immunity

based on antibodies.

(for example, vaccines).

Takes 21 days to develop.

Very focused on one

microbe (such as this year’s

flu shot).

“broad-spectrum” general

protection.

Not specific to one microbe.

Not based on antibodies.

Keeps you alive for the 21

days until Specific Immunity

kicks in.

How does innate immunity work?

Partly through Antimicrobial Peptides.

Very small proteins that can kill bacteria.

Made by most higher organisms.

http://cmr.asm.org/content/19/3/491/F1.large.jpg

Structural classes of

antimicrobial peptides.

(A) Mixed structure of human β-

defensin-2

(B) looped thanatin

(C) β-sheeted polyphemusin

(D) rabbit kidney defensin-1

(E) α-helical magainin-2

(F) extended indolicidin.

Jenssen H et al.

Clin. Microbiol. Rev.

2006;19:491-511

Antimicrobial peptides kill bacteria.

Bacteria

Surface

Antimicrobial

Peptide

Bacteria make biofilm

What is Biofilm?

Resistance Cloak for Bacteria.

Protects them against antibiotics & your immune system.

80% of bacterial infections may be biofilm mediated.

http://7bigspoons.com/wp-content/uploads/2012/05/Bacteria-wearing-an-acid-resistant-rain-coat.png

We can make “anti-biofilm”

antimicrobial peptides

Natural and synthetic cathelicidin peptides with anti-microbial and anti-biofilm activity against Staphylococcus aureus. Dean SN, Bishop BM, van Hoek

ML. BMC Microbiol. 2011 May 23;11:114.

Susceptibility of Pseudomonas aeruginosa Biofilm to Alpha-Helical Peptides: D-enantiomer of LL-37. Dean SN, Bishop BM, van Hoek ML. Front

Microbiol. 2011;2:128.

Control LL-37-treated

a

0

10

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Untreated LL-37

Max

imu

m t

hic

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m)

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S. aureus

P. aeruginosa

mixed

d

0

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10

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Untreated LL-37

Bio

ma

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(µ

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m2)

Control LL-37-treated

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20

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60

Untreated LL-37

Ma

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S. aureus

P. aeruginosa

mixed

d

0

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Untreated LL-37

Bio

ma

ss

(µ

m3/µ

m2)

Where else can we find new antibiotics?

We can take antimicrobial peptides

and make them better

Naja atra, the Chinese cobra

Atra-1 Atra-2 Naja atra

CATHELICIDN

Atra-1 Atra-1 NA-CATH:

ATRA1-ATRA1

Antimicrobial activity of the Naja atra cathelicidin and related small peptides. de Latour FA, Amer LS, Papanstasiou EA,

Bishop BM, van Hoek ML. Biochem Biophys Res Commun. 2010 Jun 11;396(4):825-30.

Crocodiles & Alligators

Why crocodiles?

Seem resistant to skin/wound infection, despite living in swamps.

Evolutionarily ancient

have had millennia to select the best ways of fighting off infection.

Crocodile/Alligator Blood is known to have antimicrobial properties.

The genome is not sequenced yet.

Attempts have been made to find antimicrobial peptides – mostly unsuccessful.

How to purify an antimicrobial peptide.

http://img1.etsystatic.com/005/0/6998440/il_fullxfull.372374857_mn7m.jpg

One precious tube

of alligator or

crocodile blood.

Now what?

BioProspecting: A new way to

purify an antimicrobial peptide

obtain antimicrobial peptides from

many kinds of natural samples.

Blood, urine, saliva, etc.

“Bio-prospecting”.

quickly capture new antimicrobial

peptides from samples

use advanced modern biochemical

technologies

Nanomaterials & Nanoparticles

Advanced Mass Spectrometry to

identify antimicrobial peptides.

http://images1.wikia.nocookie.net/__cb20110901171834/minecraft-tutorials/images/7/72/5995531-1-.jpg

BioProspecting

Recover particle w/ harvested peptides.

Large Volume Complex Sample

(eg Crocodile Blood)

Concentrated, Isolated Peptides

Small peptides trapped (and protected)

Sieving Shell

Binding core

BioProspector Particle

New Crocodile Peptide

Using multiple techniques, we identified a new Crocodile

Antimicrobial peptide.

We called it “CHOMP”

It kills lots of different bad bacteria in the lab.

It is similar, but not identical, to a known “class” of antimicrobial

peptides.

http://ars.els-cdn.com/content/image/1-s2.0-S1074552110004813-gr1.jpg

Our Dream….

“CROCOSILLIN”

Summary:

It is critical to conserve antibiotics as a precious resource.

We have to work urgently to develop new antibiotics.

We have to be creative in how we find new antibiotics.

http://blogs.smithsonianmag.com/science/files/2011/07/crocodile_smile.jpg

Recent Publications

Acknowledgements

Scott Dean

Frank Delatour

Stephanie Barksdale

Myung Chung

Collaborators:

Dr. Barney Bishop, Department of Chemistry, George Mason

University

Dr. Joel Schnur, College of Science, George Mason

University

Funding: DTRA “Translational Peptides for Personnel

Protection”