Update on
Antimicrobial Research
Prepared for Florida Citrus
Industry Annual Conference
Bonita Springs, FL
June 12, 2014
Requirements for Management
• Slow spread of disease – CHMA and insect
control
• Treat existing infected trees
• Protect new plantings
• Provide long-term sustainable genetic and
biological solutions
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Requirements for Management
• ✔ Slow spread of disease – CHMA and psyllid
control
– Stewardship of existing products
– Label expansions
– Bee health - coordination
– New insect control actives
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Requirements for Management
• Treat existing infected trees
– Enhanced nutritionals
– Plant growth regulators
– Naturally occurring microbes
– Thermal therapy
– Antibacterial compounds
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Outline
• Perspective – science, business, regulatory,
market aspects of current challenge
• Definitions – different languages
• Resources available today
• What have we learned?
• Pipeline of bactericides
• From where will the next products come?
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Some Definitions
• Antibacterial treatments
• Bactericides and Pesticides
– Biopesticides (Microbial and Biochemical)
– Antibiotics
• Use pattern, residues, tolerance or exemption
• Science
– evidence over opinions, assumptions explicit,
bounds what is known as well as what is
unknown, creates technology options
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Probability
Time to Market - Present Investment
Vector
Pathogen
Host
3 YR
6 YR
9 YR
Time
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Bactericides for Crops
• To our knowledge in all of US there are only
three bactericides approved for use on food
crops (excluding copper); Oxytetracycline,
Streptomycin and Kasugamycin
• This problem is much bigger than citrus but it
is ours to solve
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Registration of a New Active
• A partial list of studies required by EPA
(Additional agencies may include USDA-APHIS, FDA, CDC)
–(GLN 835.1240) Soil Column Leaching and (GLN 835.2410)
Photodegradation of Parent and Degradates in Soil, (GLN
835.6100) Terrestrial Field Dissipation
–(GLN 835.4200) Anaerobic Soil Metabolism, (GLN 835.4100)
Aerobic Soil Metabolism, (GLN 835.4300) Aerobic Aquatic
Metabolism and (GLN 835.4400) Anaerobic Aquatic
Metabolism
–(GLN 835.2120) Hydrolysis of Parent and Degradates as a
Function of pH at 25° C and (GLN 835.2240) Direct
Photolysis Rate of Parent and Degradates in Water
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Registration of a New Active
• Some more EPA data requirements
– (GLN 850.1025) Oyster Acute Toxicity, (GLN 850.1035)
Mysid Acute Toxicity, (GLN 850.1075) Saltwater Fish Acute
Toxicity, (GLN 850.1075) Freshwater Fish Acute
Toxicity,(GLN 850.1300) Freshwater Invertebrate Life Cycle,
(GLN 850.2300) Avian Reproduction, (GLN 850.1010)
Freshwater Invertebrates Acute Toxicity
– (GLN 850.4100) Terrestrial Plant Toxicity – Tier 1 Seedling
Emergence, (GLN 850.4150) Terrestrial Plant Toxicity – Tier
1 Vegetative Vigor, (GLN 850.4400) Aquatic Plant Toxicity –
Tier 1 Vascular, (GLN 850.5400) Aquatic Plant Toxicity –
Tier 1 Nonvascular
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Registration of a New Active
• Further animal EPA data requirements
– (GLN 850.2100) Avian Oral Toxicity, (GLN 850.2200) Avian
Dietary Toxicity
– (GLN 850.3020) Honeybee Acute Contact Toxicity
• Human health
– (GLN 870.7800) Immunotoxicity
– Resistance studies with human pathogens planned for
frequency of resistance determination
• Other studies as directed…
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Citrus Greening Disease (Huonglongbing)
SEARCH FOR
AGRICULUTRAL
THERAPEUTICS
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Biological Assays
• Graft-based assay
– Infected scion soaked in test solution and grafted
onto uninfected rootstock, follow by PCR
– Slow, low-throughput
– Evidence of efficacy in planta and first look at
phyto-toxicity
– Open contest with InnoCentive™ promotion
• Liberibacter crescens culture-based assay
– Much faster, higher-throughput followed by in
planta confirmation on CLas
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Prior Results
• Compounds screened
– ~100+ by graft graft assay and
– ~400+ by culture assay
• Wide variety of categories of chemicals
– Antibiotics and agricultural antibiotics
– Polycation polymers
– Biopesticides, plant essential oils, terpenoids
– New actives and non-antibiotic derivatives
– Host immune modulators
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What are we looking for?
• HLB treatment; effects on tree symptoms
through CLas titre reduction
• Sources: Solutions Page, Research, Companies
• Chemical properties
– MW:
– Log Kow:
– pKa:
< 450 g/mol preferably < 250 g/mol
2 to 4
2 to 6.5 preferably 3 to 5.5
• Volume of phloem: 10 ft tree, 1000 L
• ? pH: 8.0 – 6.0 stylectomy vs fractionation
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Relationships
• Looking inside the box…
– Companies, facilitate turn-key screening
• Looking outside the box…
– Repurpose products with regulatory advantage
– Failed antibiotics with good safety profiles
– 25(b) minimal risk pesticides
– All commercial compounds fitting our chemical
profile and having existing tolerances on other
food crops
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Current Testing Resources
Liquid Culture Assay on L. crescens ➪ MIC90
(Dr. Erik Triplett Laboratory)
Citrus Flush Assay on C. asiaticus ➪ Confirmation
(Dr. Claudio Gonzalez)
Trunk Injection ➪ Dose
(Dr. Nian Wang)
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Requirements and Results
Liquid Culture Assay on L. crescens ➪ MIC90
< 1 mg of compound, ~ 2 weeks for results
Citrus Flush Assay on C. asiaticus ➪ Confirmation
~ 100 mg of material, ~ 1 month
Trunk Injection ➪ Dose
> 10 gr of material, 2-7 months
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Risk Remaining at this Stage
• Technical
– Commercial scale delivery, efficacy, phytotoxicity
•
•
•
•
Cost
Regulatory
Commercial Partner(s)
Market acceptance
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Build on Success–Expanding Teams
• Pivot our focus – connecting corporations
• Sponsored research base from CRDF and
others, researchers, reviewers, public solutions
• Improved communication; knowledge and data
sharing between and within grower, researcher,
government, corporate sectors
• CRDF Board and Committees; RMC, CPDC, IRCC
• Research pipeline now enhanced with
government funding $21mm MAC, $25mm SCRI
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What comes next?
1. Field trials with top priority
Category of Compounds
Description
Partner
Antibiotics
Oxytetracycline
Streptomycin
(Kasugamycin?)
Commercial
GRAS-like
Plant Essential Oils
Natural Products
– cymene, carvacrol, etc.
CRDF-sponsored
formulation research
2. Field trials with major challenges
Category of Compounds
Description
Partner
Agricultural Antibiotics
Zhongshengmycin
Validoxylamine A
Source? - Research
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3. Field trials with commercial partners
Category of Compounds
Description
Partner
Biopesticides
Surfactin (lipopetides)
Company C
Host Immune Modifiers
One marketed compound
One pipeline compound
Company C
4. Development pipeline
Category of Compounds
Description
Partner
Polycation polymers
Proprietary biodegradable polymers
Company D
Bacterial protein target
LdtR
Lead refinement
- Highly active, no human homolog,
transcription regulator, essential
role in cell wall remodeling
Company D
Company D
(Wang)
Lead refinement
- Highly active, no human homolog,
protein secretion, essential role in
effector secretion
Non-antibiotic derivatives
Tetracycline derivatives
Company E
(Gonzalez)
Bacterial protein target
SecA
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Acknowledgements:
Bob Shatters, USDA-Ft. Pierce, FL
Ed Stover, USDA-Ft. Pierce, FL
Chuck Powell, UF-Ft. Pierce, FL
Ping Duan, USDA-Ft. Pierce, FL
Muqing Zhang, UF-Ft. Pierce, FL
Eric Triplett, UF-Gainesville, FL
Brij Moudgil, UF-Gainesville, FL
Parvesh Sharma, UF-Gainesville, FL
Nian Wang, UF-Lake Alfred, FL
Claudio Gonzalez, UF-Gainesville, FL
Mark Nelson, Echelon Corp.
Jim Dukowitz, Technology Innovation Group
Harold Browning, Jim Syvertsen, CRDF
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Contact:
catp@citrusrdf.org
solutions@citrusrdf.org
tom.turpen@innovationmatters.com
THANK-YOU
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