Transcript Dr. P. Balakrishna Murthy - IGMORIS

New Challenges in Toxicity/Safety Studies
with Biotech Based Products
Dr.P.Balakrishna Murthy, Ph.D., D.Sc.,
Director
International Institute of Biotechnology And Toxicology (IIBAT)
(A GLP Certified Lab)
Padappai – 601 301, Kancheepuram Dist., Tamil Nadu, India
Phone:04111-274246/274266; Fax:04111-274455
E-Mail: [email protected]
Risk Analysis
Biosafety and Bioethics
• Impacts of biotechnology on human, animal,
plant health and the environment.
• Biotechnology product risk assessment needs
larger scientific capacity
Biotech Products
• Types of Biotech products
•
•
•
•
Crop/Food
Drugs
Gene therapy products
Vaccines
• Characteristics of biotech products
• Impact of production, process, quality on safety
Scientific Issues Concerned to
Biotech Based Products
• Alterations in the coding sequence of the cloned
gene
• Alterations in the chemical/protein structure
• Contaminants
• Adventitious agents
• Stability
• Environmental effects
Crop Biotechnology Developments
Crop Biotechnology
Input Traits
Insects / Disease
Resistance
Output Traits
Herbicide
Tolerance
Yield and
Quality
Chemical
Production
Bt Cotton
Vit. A rice
1980
onwards
1995
onwards
Agronomic Characteristics
Plant
Biochemistry
2000
onwards
Plant
Physiology
Transgene Insertion in Plant DNA
Delivery of DNA
in to cell
Integration of transgenes via natural
Pathway of DNA recombination
Deletions/insertions in recombination
Locus/Typical bias for gene-rich regions
Creation of new
genetic variability
Unintended effects
Toxicological Issues in Transgenic Food
Known toxins
Legumes – lectins and glycosides
Crucifera – glucosinolates
Cucumber – cucurbitin
Chickpea - lathyrogens
Gene transfer – increase toxin production
Reasons for Unintended Effects
• Random integration of transgenes
• Insertional mutagenesis
• Disruption of endogenous gene
functions
– Gene activation/inactivation
– Production of new proteins
changes in
* enzymes
* metabolites
* phenotype
Safety Assessment of Transgenic Food
Unintended Effects
Specific analysis
Targeted approach
Profiling techniques
Non-targeted approach
Targeted Approval - Animal Studies
Identification of hazard/risk
Tolerance limits
Acute & long term toxic effects
ADI, NOEL
Risk predictions to man
Animal Toxicity Studies*
Whole
animal,
food/gene/protein
whole
Appropriate
controls/traditional hybrid
food/Non-GM
Acute studies - LD50,
Skin/Allergy reaction
Feeding
trials
in
rat/rabbit/goat - 90 days clinical,
hematological,
biochemical,
immunological, necropsy &
detailed HP.
* GLP Compliance
Animal Studies
Acute/Short-term
– Oral, dermal, inhalation
– Short-term reactions/clinical
symptoms/mortality
– LD50
Sub-Acute
_ 90 day feeding studies
_ NOEL
Chronic
_ Life long feeding study
_ Cancer-transplacental cancer
risk
Others
_ Mutagenic, Allergenic,
Neurotoxic, Reproductive
toxic/embryotoxic/teratogenic
- Immunotoxic
Non-Targeted Approval - Profiling
Techniques
Genomics
DNA microarrays
Proteomics
2-D gel electrophoresis
Metabolomics
NMR, GC-MS, LC-MS
The Safety of Biotech Based Products
Food/Feed
Gene / Protein Safety
and
Environmental Safety
 Gene(s)



 Crop Characteristics
Source(s)
Molecular characterization
Insert / copy number / gene integrity
 Protein(s)

History of safe use and consumption
Function / specificity / mode of action
Levels

Toxicology/ allergenicity testing


Crop Safety



 Environmental Safety
Morphology
Yield
Food/Feed
Composition



Proximate analysis
Key nutrients
Key anti-nutrients
Determination of the Biological Potency
TBL 1
Target
Entire organism
In vivo
In vitro
Skin
Species
Test System
Examples
Human
Challenge of
allergic patients
DBPCFC, open
challenges
Experimental animals
Peroral challenge of
animals
Anaphylactic
response
Human
Skin testing of
allergic patients
Skin prick tests,
intrademal tests
Experimental animals
Actively or
passively sensitized
animals
PCA
Basophil histamine
release, cord blood
basophil histamine
release
Mediator release
Basophils
Humal
Actively or
passively sensitized
basophils + allergen
Basophil or mast
cells
Humanized i.e. transfected
with a human iGE receptor
Passively senstized
cells
Rodents
Histamine or other
Peritoneal mast cells mediator release
Mast cells
RBL-2H3
DNA and Protein Detection Studies
 Broilers
 Layer hens
 Beef
 Dairy
Biotech Based Drugs/Vaccines
Safety Assessment of Gene Therapy Products
• Background to gene therapy
• Principles in design of testing programme
• Distribution and expression of gene and vector
• Pharmacological end points
• Impact of quality and safety
Pharmacogenomics
• Concerned with individual response to drugs based on genetic
make-up
• Pharmacogenomics is a very recent, but fast-moving area of
research, which is likely to revolutionize health care.
• Genetic analysis of individuals, and ready access to a wide range of
drug options
• Finding the most suitable drug and dosage for a specific patient is
done on trial-and-error basis
• Dosage is calculated according to weight of the patient.
• Understanding these process through genetic analysis of individual
patients is likely to lead to more effective treatment and improved
drug development
Requirements of Protein derived
from Modern Biotechnology
• They are from sources with no history of toxicity or allergy
• They do not resemble known toxins or allergens
• They have well understood functions
• They are expressed at low levels (major allergens are usually found
in large amounts in allergenic foods)
• They are rapidly degraded in the stomach (within minutes)
• There is a lack of adverse effects in mice at high levels of
consumption
• Animal feeding studies (such as a 42-day poultry trial) do not
reveal any adverse effects
Biotechnology and the Public
 Overwhelming majority - optomistic about
biotechnology
 Public is seeking unbiased information
 Acceptance improves with brief factual
explanations
 Trusted messengers - doctors, scientists,
nutritionists, farmers, govt. agencies
Source: Hoban 1996, 1999, Hoban and Katic, 1998