Roadmap for Vector Transmission Control (VTC)

What are we trying to achieve and why? What is the problem we are trying to solve?

To decrease pathogen load in vectors by increasing vector resistance to pathogen infestation

What are the scientific and technological challenges (knowledge gaps needing to be addressed)?

Determine vector physiological and immunological pathways that decrease pathogen replication in the vector
Co-evolution/symbiotic evolution makes it difficult to disrupt and boost immune response of ticks to pathogens that parasitize the vector, it might be easier to control the vector than it is to control the pathogens within it
Investigating the symbiotic relationship between ticks and their hosts could provide insights into new strategies for tick control. For example, understanding how ticks acquire and transmit pathogens could lead to new approaches for interrupting the transmission cycle.
Need to consider cost-effectiveness and applicability in field by considering delivery and technologies (e.g., micro capsules)
Determine how to stimulate tick innate immunity: can RNAi be used for mosquito larvae, how can we deliver such a stimulus for ticks (spray and micro capsules) – pharmaceuticals
There is limited understanding of the feasibility of using RNA for tick control? How can it be delivered as a commercial product? Need for more effective methods for delivering RNA technology. While there
have been studies on delivering RNA technology to cattle via microcapsules or pharmacological formulations, there is still a need for more effective methods. Further research is needed to identify new delivery methods that can be used commercially and improve treatment outcomes.
There is a need for more research on pathogen competence and symbiosis in insect vectors: While there have been studies on competition between bacteria in flies and symbiosis within tsetse flies, there is still a need for more research on these topics. Further research is needed to better understand how different pathogens interact with each other and with their insect hosts.
Transgenesis has been used to modify both mosquitoes and bacteria, however our understanding of the impact of these modifications on vector capacity is still limited. Further research is needed to determine how transgenesis can be used to reduce disease transmission by insect vectors.
Is it feasible to use application of plasmids for tick control in the field?
Bacterial and viral microbiota/infection can alter the pathogen transmission of the vector

What approaches could/should be taken to address the research question?

Genetically modify vectors to prevent pathogen replication and/or transmission
Analyse natural differences in pathogen concentrations between vector populations (species): it might be that certain vector phenotypes or genotypes are more able to control the pathogen within them
Increase our understanding of innate and acquired resistance of insect vectors: e.g., while it is known that female tsetse flies can develop resistance to viruses and Spiroplasma, our understanding of the mechanisms behind this resistance are still limited. Further research is needed to identify the factors that contribute to innate and acquired
resistance in insect vectors and how this resistance may impact disease transmission.

What else needs to be done before we can solve this need?

Improved our understanding of the vector pathogen interaction including the pathogen cost to the vector

Existing knowledge including successes and failures

Induce systemic tick immunity through gene editing – not practical/feasible
Jasinskas A, Barbour AG (2005). The Fc Fragment Mediates the Uptake of Immunoglobulin G from the Midgut to Hemolymph in the Ixodid Tick Amblyomma americanum (Acari: Ixodidae). Journal of Medical Entomology, Volume 42, Issue 3, 1 May 2005, Pages 359–366,
Zhong J, Jasinskas A, Barbour AG (2007). Antibiotic treatment of the tick vector Amblyomma americanum reduced reproductive fitness. PLoS One 2: e405

Shi et al. 2022 Bidirectional interactions between Arbovirusses and the bacterial and viral microbiota in Aedes aegypti and Culex quinquefqsciatus. mBIO13, 5
Hobson-Peters et al. 2013 A new insect-specific flavivirus from northern Australia suppresses replication of West Nile Virus and Murray Valley Encephalitis Virus in Co-infectde mosquito cells. PLOSone 2013, 8,2 e56534
Hall-Mendelin et al. 2016 The insect-specific Palm Creek virus modulates West Nile virus infection in and transmission by Australian mosquitoes. Parasites and Vectors 9, 414.
Schutz et al 2018 Dual insect specific virus infection limits Arbovirus replication in Aedes mosquito cells. Virology 518, 406-413.