Ethical, legal and social issues of genetically modifying insect vectors for public health

Public health concerns over gene-drive mosquitoes: will future use of gene-drive snails for schistosomiasis control gain increased level of community acceptance?

With the advent of CRISPR (clustered regularly interspaced short palindromic repeat)-based gene drive, present genetic research in schistosomiasis vector control envisages the breeding and release of transgenic schistosome-resistant (TSR) snail vectors to curb the spread of the disease. Although this approach is still in its infancy, studies focussing on production of genetically modified (GM) mosquitoes (including gene-drive mosquitoes) are well advanced and set the pace for other transgenic vector research. Unfortunately, as with other GM mosquitoes, open field release of gene-drive mosquitoes is currently challenged in part by some concerns such as gene drive failure and increased transmission potential for other mosquito-borne diseases among others, which might have adverse effects on human well-being. Therefore, not only should we learn from the GM mosquito protocols, frameworks and guidelines but also appraise the applicability of its current hurdles to other transgenic vector systems, such as the TSR snail approach. Placing these issues in a coherent comparative perspective, I argue that although the use of TSR snails may face similar technical, democratic and diplomatic challenges, some of the concerns over gene-drive mosquitoes may not apply to gene-drive snails, proposing a theory that community consent will be no harder and possibly easier to obtain for TSR snails than the experience with GM mosquitoes. In the future, these observations may help public health practitioners and policy makers in effective communication with communities on issues regarding the use of TSR snails to interrupt schistosomiasis transmission, especially in sub-Saharan Africa.

Locally Fixed Alleles: A method to localize gene drive to island populations

Invasive species pose a major threat to biodiversity on islands. While successes have been achieved using traditional removal methods, such as toxicants aimed at rodents, these approaches have limitations and various off-target effects on island ecosystems. Gene drive technologies designed to eliminate a population provide an alternative approach, but the potential for drive-bearing individuals to escape from the target release area and impact populations elsewhere is a major concern. Here we propose the “Locally Fixed Alleles” approach as a novel means for localizing elimination by a drive to an island population that exhibits significant genetic isolation from neighboring populations. Our approach is based on the assumption that in small island populations of rodents, genetic drift will lead to alleles at multiple genomic loci becoming fixed. In contrast, multiple alleles are likely to be maintained in larger populations on mainlands. Utilizing the high degree of genetic specificity achievable using homing drives, for example based on the CRISPR/Cas9 system, our approach aims at employing one or more locally fixed alleles as the target for a gene drive on a particular island. Using mathematical modeling, we explore the feasibility of this approach and the degree of localization that can be achieved. We show that across a wide range of parameter values, escape of the drive to a neighboring population in which the target allele is not fixed will at most lead to modest transient suppression of the non-target population. While the main focus of this paper is on elimination of a rodent pest from an island, we also discuss the utility of the locally fixed allele approach for the goals of population suppression or population replacement. Our analysis also provides a threshold condition for the ability of a gene drive to invade a partially resistant population.

Biological control of pests and a social model of animal welfare

This paper considers the sociocultural implications of biological pest control that sit at the cusp of managing an invasive species for conservation or productivity (i.e. a 'natural enemy') and socially driven 'manipulating life' arguments. We consider the role of perceived humaneness or, more accurately, animal welfare as it relates to managing invasive species from a scientific and social perspective. In order to highlight and articulate particular nuances and standards across different pest control contexts, we use three case examples (feral cats, wild rabbits, and invasive cane toads) and explore where biological pest control and animal welfare interests intersect. The paper summarises key scientific welfare concerns and then extends the literature to also examine key social characteristics of each pest management scenario, including lay perceptions of animal welfare, the sociocultural context that pests exist within, and overarching psychological factors contributing to public sentiment, including perceived risks. The subsequent descriptive model presented is useful in articulating core sociocultural beliefs relative to each case and how these antecedent associations and attitudes about an animal influence subsequent beliefs about a pest management strategy and ultimately acceptance of the management approach. The model can inform invasive species management policies and highlight key sociocultural factors likely to influence public responses. The model also informs interdisciplinary science designed to develop acceptable and socially responsible biocontrol strategies that consider public perceptions of animal welfare and cultural appropriateness.

Technoscience and Biodiversity Conservation

The discovery of CRISPR/Cas9 has opened new avenues in gene editing. This system, usually considered as molecular scissors, permits the cutting of the DNA at a targeted site allowing the introduction of new genes or the removal or the modification of existing ones. The genome-editing, involving gene drive or not, is then considered with a strong interest in a variety of fields ranging from agriculture to public health and conservation biology. Given its controversial aspects, it is then no surprise that actors in biodiversity conservation do express conflicting views on this emerging and disruptive technology. The positions are ranging from a request for a moratorium to the will to test and deploy it in strategies aiming at eradicating invasive species of mammals on islands. Reviewing some of its recent developments brings light on the conflicts of interest, the financial support, and lobbying currently occurring in this growing field of biotechnology. While an optimistic view on the use of gene drive for ecosystem conservation was first promoted by several molecular biologists, the risks and uncertainties associated have now led to some reservations. Overall, the eventual use of this novel approach for conservation raises concerns related to the engagement of the public, the communication between scientists, and the public and the risk of a manufactured consent. There are also a series of essential ethical and philosophical questions on the relations we have with Nature that needs to be answered.

Teilhard de Chardin's oeuvre within an ongoing discussion of a gene drive release for public health reasons

Within the domain of public health, vector-borne diseases are among the most vehemently discussed issues. Recent scientific breakthroughs in genome editing technology provided a solution to this issue in the form of a gene drive that might decrease and even eradicate vector-borne diseases. Gene drives are engineered, and designed genes that can break typical inheritance rules and be passed to almost all of the carrier's offspring. This genome editing and gene drive technology has become a powerful tool for ecological and environmental engineering, through which man can manipulate his surroundings, adjusting it to himself and directly mastering evolution and the ecosystem. Although the gene drive technology has been perceived as promising in the public health domain, ecological implications of its use are not to be underestimated. The primary aim of this paper is to overcome the ongoing discussion which mostly focuses on whether priority should be given to the environment or to public health, and to find an adequate answer and solution. In this quest to find the proper answer and solution, Pierre Teilhard de Chardin's thought might be useful, especially his concepts of the biosphere and the noosphere which may provide some clarifications as to why we are at the moment so cautious with gene drive technology and how we need to move towards a better common future on earth.

Effect of Irradiation Doses on Sterility and Biological Security in a Genetically Modified Strain of the Mediterranean Fruit Fly (Diptera: Tephritidae)

The genetically modified strain of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) VIENNA 8 1260, was developed from the genetic sexing strain VIENNA 8. It has two molecular markers that exhibit red fluorescence in the body and green fluorescence in testis and sperm. These traits offer a precise tool to discriminate between mass-reared and wild males, increasing the effectiveness of sterile insect technique. The reproductive performance of the VIENNA 8 1260 and VIENNA 8 D53- (without the D53 inversion introduced to prevent recombination) was compared at different irradiation doses. The general effect of irradiation on VIENNA 8 1260 followed the same patterns documented in previous publications for VIENNA 8 D53-. Irradiation doses of 80 Gray or greater reduced fertility and induced high levels of sterility in wild females. Fecundity reduction was higher in VIENNA 8 1260 than in VIENNA 8 D53- females. Vertical transmission of the fluorescence gene was confirmed up to the F4 generation. Substerilization in the VIENNA 8 1260 could jeopardize the usefulness of the transgenic strain due to the possible vertical transfer of the fluorescence transgene from the sterile males to the wild flies. A biologically safe higher irradiation dose could result in reduced competitiveness of the VIENNA 8 1260 strain. Mating and remating experiments suggest that Mediterranean fruit fly females exhibit a relative precedence in the use of the sperm: though both sperms are mixed, sperm from the remating is spent first. Results suggest a lower fitness of VIENNA 8 1260 sperm, when compared with sperm from a nonfluorescent bisexual strain, which is consistent with the lower reproductive performance documented for the VIENNA 8 1260 strain.

A role for vector control in dengue vaccine programs

Development and deployment of a successful dengue virus (DENV) vaccine has confounded research and pharmaceutical entities owing to the complex nature of DENV immunity and concerns over exacerbating the risk of DENV hemorrhagic fever (DHF) as a consequence of vaccination. Thus, consensus is growing that a combination of mitigation strategies will be needed for DENV to be successfully controlled, likely involving some form of vector control to enhance a vaccine program. We present here a deterministic compartmental model to illustrate that vector control may enhance vaccination campaigns with imperfect coverage and efficacy. Though we recognize the costs and challenges associated with continuous control programs, simultaneous application of vector control methods coincident with vaccine roll out can have a positive effect by further reducing the number of human cases. The success of such an integrative strategy is predicated on closing gaps in our understanding of the DENV transmission cycle in hyperedemic locations.

Engaging scientists: An online survey exploring the experience of innovative biotechnological approaches to controlling vector-borne diseases

Background

Pioneering technologies (e.g., nanotechnology, synthetic biology or climate engineering) are often associated with potential new risks and uncertainties that can become sources of controversy. The communication of information during their development and open exchanges between stakeholders is generally considered a key issue in their acceptance. While the attitudes of the public to novel technologies have been widely considered there has been relatively little investigation of the perceptions and awareness of scientists working on human or animal diseases transmitted by arthropods.

Methods

Consequently, we conducted a global survey on 1889 scientists working on aspects of vector-borne diseases, exploring, under the light of a variety of demographic and professional factors, their knowledge and awareness of an emerging biotechnology that has the potential to revolutionize the control of pest insect populations.

Results

Despite extensive media coverage of key developments (including releases of manipulated mosquitoes into human communities) this has in only one instance resulted in scientist awareness exceeding 50 % on a national or regional scale. We document that awareness of pioneering releases significantly relied on private communication sources that were not equally accessible to scientists from countries with endemic vector-borne diseases (dengue and malaria). In addition, we provide quantitative analysis of the perceptions and knowledge of specific biotechnological approaches to controlling vector-borne disease, which are likely to impact the way in which scientists around the world engage in the debate about their value.

Conclusions

Our results indicate that there is scope to strengthen already effective methods of communication, in addition to a strong demand by scientists (expressed by 79.9 % of respondents) to develop new, creative modes of public engagement.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-015-0996-x) contains supplementary material, which is available to authorized users.

Engineered mosquitoes to fight mosquito borne diseases: not a merely technical issue

Malaria, dengue and other mosquito-borne diseases pose dramatic problems of public health, particularly in tropical and sub-tropical countries. Historically, vector control has been one of the most successfully strategies to eradicate some mosquito-borne diseases, as witnessed by malaria eradication in Mediterranean regions such as Italy and Greece. Vector control through insecticides has been used worldwide; unfortunately, it is losing effectiveness due to spread of resistances. Control of mosquito-borne diseases through field-releases of genetically engineered mosquitoes is an innovative and now feasible approach. Genetically modified mosquitoes have already been released into the wild in some regions, and protocols for this release are on hand in others. Local authorities are vigilant that transgenic insects in the field are safe for human and animal populations, and the public engagement in every control program is assuming a central role.

Scientists and public involvement: a consultation on the relation between malaria, vector control and transgenic mosquitoes

Among the hopes for vector-based malaria control, the use of transgenic mosquitoes able to kill malaria parasites is seen as a potential way to interrupt malaria transmission. While this potential solution is gaining some support, the ethical and social aspects related to this high-tech method remain largely unexplored and underestimated. Related to those latter points, the aim of the present survey is to determine how scientists working on malaria and its vector mosquitoes perceive public opinion and how they evaluate public consultations on their research. This study has been performed through a questionnaire addressing questions related to the type of research, the location, the nationality and the perception of the public involvement by scientists. The results suggest that even if malaria researchers agree to interact with a non-scientific audience, they (especially the ones from the global North) remain quite reluctant to have their research project submitted in a jargon-free version to the evaluation and the prior-agreement by a group of non-specialists. The study, by interrogating the links between the scientific community and the public from the perspective of the scientists, reveals the importance of fostering structures and processes that could lead to a better involvement of a non specialist public in the actual debates linking scientific, technological and public health issues in Africa.