Regulatory Considerations and Management Practices for the commercial-scale release of

transgenic mosquitoes in Brazil

Dr. Paulo Paes de Andrade

Federal University of Pernambuco Recife – Brazil

Colombo Sri Lanka September 2014

Dengue world distribution

Evolution of the incidence of dengue fever in Brazil

Incidence (per 100,000 people) 0 0<100 100 to 300

300 to thousand

> thousand

Source: http://atuabio.blogspot.com.br/2013/02/dengue.html

Source: http://portal.saude.gov.br/portal/arquivos/pdf/dados_dengue_classica_2012_at032013.pdf

Dengue cases in Brazil : 1990 - 2012

1 million cases/ year Overall population: 200 million

Sanitary inspection

Environmental management

Information and communication

Complexity in control logistics

+

+

Both agencies and urban inhabitants

involved

Expected individual contributions

A new control strategy to be added to the existing ones: genetically modified RIDL Aeades aegypti

The repressor is tetracycline, a semi- synthetic antibiotics used in animal husbandry

Source: http://www.oxitec.com/ridl-science/understanding-ridl-science/molecular-biology/

As a consequence of the introduction of large samples of OX513a males, the endemic (wild) population of Aedes aegypti is expected to sharply fall – therefore

also blood-sucking female mosquitoes

This hypothesis has been proved by the results of many controlled field releases in different countries and,

especially, in Brazil

If the systematic release of such insects will reduce dengue transmission remains to be proved, but it is

highly plausible.

Risk assessment of genetically modified OX513aA. Aegypti

General principles of risk assessment, adopted by the official risk assessment agents, including the Brazilian CTNBio

Case by case Comparative (with a non GM similar organism) Step by step Science-based Looks only at biological risks

Risk assessment is usually the duty of a group of scientists/technical assistants skilled on molecular and cell biology, genetics, epidemiology, microbiology, food security, etc. At CTNBio there are 54 members and ca. 12 assistants.

The five steps in risk assessment

An adequate Problem Formulation (and Risk characterization) warrants a successful R.A.

Problem Formulation: the context For a genetically modified OX513a A. Aegypti, released for

commercial use (unconstrained use) in Brazil

Regulatory framework Biology of parental organism Genetic construct Receiving environment Impacted organisms Familiarity History of safe use

Defines responsibilities and general protection goals

Knowledge of gene flow, persistence in the environment, etc.

New proteins, iRNA, knockouts, expression levels, etc.

Biota interacting with the GMO by different mechanisms in area where it will be effectively used

Inferred from the above elements --- list of hazards

Knowledge derived from the use of a non-GM product of similar characteristics

Knowledge derived from the use of the same or very similar GMO in other countries GMO

Problem Formulation: the context For a genetically modified OX513A A. Aegypti, released for

commercial use (unconstrained use) in Brazil

Protection goals: as defined by the law - the environment + human & animal heath --- the goals are far too generic.

From the biology of A. aegypti we know it is found only in urban areas, within or near human dwellings (at least in Brazil) ----- the protection goals must be translated in assessment endpoints existing in this special environment (where the GM mosquito will also be released)

A. aegypti is highly anthropophilic and transmit diseases only to a few human and non-human primates (not existing in Brazilian urban areas). It does not mate wit other native mosquito species (and essentially with no other mosquito)

Problem Formulation: the context (ctn.)

No animal feeds exclusively on A. aegypti (or on any mosquito species). Those feeding on them ARE NOT VALUED SPECIES and, therefore, are not protection goals, per se.

As a consequence, there are no plausible assessment endpoints except the human being

What are the issues (list of hazards) for human beings, keeping in mind that only the DIRECT biological impact of the GM mosquito is considered in risk assessment? (Impacts of the technology are the subject of risk analysis)

Allergy and toxicity potential of the new proteins expressed in OX513A

New infectious agents being transmitted by the GM Aedes aegypti (no scientific basis yet, the Precautionary Principle adverts… non sense assuming as real such a speculation!)

Problem Formulation: the context (ctn.) Allergy and potential toxicity of new mosquito proteins

Humans don’t usually eat mosquitoes. So, what is the route of exposure to the mosquito proteins?

Through the bite of female OX513A.

To keep in mind: Males are released (although a small percentage (<2/1000) of females is also present) and will be around for a few days (<5 days). Males do not bite However, the exposure could be extended (how much?) if the lethal trait fails (reasons may be speculated) Both the TA protein and the fluorescent marker protein are expressed In minute amounts in the salivary glands.

Hence, the likelihood of exposure to sizable amounts of the proteins is very low. Moreover, both proteins do not have allergenic epitopes and do not bear similarities to known toxins. Hence, harm extension --- if any, will be marginal.

Likelihood and consequence have to be estimated (or classified) (last step of Problem formulation or, in some cases, Risk characterization)

Risk classification (or risk estimation)

Once the likelihood and the extension of harm(also called consequences) are estimated, it is possible to classify the risk for the first proposed hazard (the proteins in the saliva).

Risk composition

• Usually, more than one hazard is considered in the R.A.

• Indeed, the initial list of hazards may be quite extensive…

• Some hazards do not materialize in risks as there are no plausible pathways to harm connecting the hazard to a defined harm to an assessment endpoint.

• For those hazards that can´t be discarded as unrealistic a pathway to harm can be constructed as a tool to estimate likelihood of occurrence of the final harm (this is typically done in risk characterization).

• For the saliva proteins it was rather simple to estimate likelihoods.

• For hazards connected to harm by many steps it may be worth constructing a full pathway to harm (there may exist more than one such pathway for each harm: the risk assessor must decide which is the most probable, based on scientific data available.

Risk of Causing Harm

(negative impact on

human health)

Escape from conditional

lethality

Yes

Expansion of the escaping

GM population

Transference of the transgene

to local non-GM A. aegypti

strains

No meaningful increased risk

Enhanced fitness of the new

populations

No

Yes Yes Yes

No No No

GM mosquito (A.aegypti)

P1 P2 P3 Pt

No meaningful increased risk

No meaningful increased risk

No meaningful increased risk

Example of a multi-step pathway to harm – OX513a A. aegypti

General hypothesis: the transgene does not work properly (there may be different reasons for that) and may be transferred to the local A. aegypti population, leading to new strains of mosquitoes with enhanced ability to transmit the disease.

Enhanced ability to transmit

pathogens

Yes

No

P4

No meaningful increased risk

Other hazards for the GM mosquito case

a) Failure of the construct to kill the mosquitoes – harm? (Direct biological impact, therefore related to R.A.

As commented before, as the trait is not fully expressed, it may warrant the survival of a small fraction of the released GM insects.

Would surviving GM mosquitoes differentially harm human beings or the environment?

CTNBio answer was: the likelihood that such survivors constitute even a very small fraction of the existing A. aegypti population is very small and the potential harm is marginal, if any. Therefore, the risk is negligible.

The same conclusion is valid for the survival due to breeding places contaminated by tetracycline, an imaginary issue (i.e., implausible hazard) frequently found in the internet.

Other hazards for the GM mosquito case (ctn.)

a) Occupation of ecological niches made vacant by the control of A. aegypti populations – main candidate: A. albopictus (Impact on health due to technology issues, not related to R.A.)

In this case, it is not the presence, but precisely the absence of Ae.aegypti that may be a risk --- not R.A, but risk analysis !!!!.

Does A. albopictus compete for the same breeding places of A. aegypti? The answer is: seldom

Does A. albopictus spread in Brazilian cities or neighborhoods still free from A.aegypti? The answer is clearly no.

Are there reports of such opportunistic niche occupation? The answer is: no unquestionable report.

CTNBio answer to this issue (although unrelated to risk assessment) was: there seems to be no reason to believe that the technology would bring more risks that not adopting it.

Risk assessment is a robust process and leads to consistent results, both for GM plants and for other GMOs

The RIDL OX513A Aedes aegypti strain does not pose significant risk for the environment or for human/animal health in Brazil

An adequate regulatory framework allows the adoption of biotechnology without bringing new risks for the environment or for human/animal health