Reversing the Dogma to find a Solution for Dengue and other Arboviruses

For much of the twentieth century, mosquito-borne diseases occupied an uneasy place in global health: too widespread to ignore, yet often overshadowed by other infectious threats. Today, orthoflaviviruses such as dengue, Zika, and yellow fever continue to impose a substantial burden across the tropics, with Latin America experiencing recurrent epidemics that strain health systems and affect millions of people. The region's warm climate, rapid urbanization, and the widespread presence of Aedes mosquitoes have made arboviruses a persistent public health challenge. 

Climate change may further amplify it. Rising temperatures and altered rainfall patterns are expanding the geographic range and seasonal activity of disease vectors, raising concerns that arboviruses could emerge in new locations or intensify in areas where they are already endemic. Diseases once considered geographically restricted may therefore acquire renewed relevance, highlighting the need for stronger surveillance, more effective interventions, and a deeper understanding of the viruses themselves. 

Among these pathogens, dengue has proven particularly difficult to defeat. Since its viral nature was recognized in the early twentieth century, researchers have pursued vaccines and antiviral treatments through multiple scientific eras, from classical virology to modern molecular biology. Yet dengue's four distinct serotypes, combined with the complex immune responses they provoke, have made the development of broadly effective and universally safe vaccines exceptionally challenging. While important advances have been achieved, including licensed vaccines and improved diagnostics, a definitive cure remains elusive, underscoring how much is still to be learned about the virus and its interactions with both human and mosquito hosts.

Progress against these diseases increasingly depends on sophisticated molecular tools that reveal how viruses replicate, evolve, and interact with their hosts and vectors. In 2025, UNU-BIOLAC supported a specialized training course on the molecular biology and biotechnology of mosquito-borne viruses, coordinated by Dr. Juan Ernesto Ludert León of CINVESTAV, with a focus on using infectious clones as a platform for studying orthoflaviviruses and other arboviruses of regional importance. The course highlighted the growing role of these technologies in vaccine development, antiviral discovery, and fundamental virology research.

In this interview, Dr. Ludert discusses why infectious clones have become indispensable tools for investigating orthoflaviviruses and how strengthening regional capacities in this area could accelerate innovation against some of Latin America's most enduring infectious diseases.

UNU-BIOLAC: What is the rationale behind designing infectious clones for studying orthoflaviviruses? What sets them apart from other viruses to require such a complex process?

JL: The dengue virus and other orthoflaviviruses' genomes (such as Zika virus or Yellow fever virus) are composed of a single-stranded RNA molecule of positive polarity (positive polarity means that it can be translated directly in the ribosomes, just like a cellular mRNA), that encodes for a single polyprotein that later is cut by cellular and viral proteases to generate 10 mature viral proteins (that is to say that the dengue genome is monocystronic, encoding a single open reading frame). All this is to illustrate that the genomes of orthoflaviviruses are impossible to manipulate with currently available technology.  For example, it is not possible to shut down the expression of any particular dengue virus protein without shutting down the expression of all the other 9 proteins. In addition, mutations can not be introduced directly into RNA molecules. And here is where infectious clones come in very handy! An infectious clone is a DNA copy of the viral RNA genome and is thus amenable to manipulation. Using infectious clone mutations to affect the function of any particular viral protein can be engineered without affecting the function of the rest of the proteins, which is very valuable.  Another advantage of infectious clones is that they can be engineered to express, in addition to the viral proteins, other proteins that will allow for the easy detection of follow up of the virus; for example, fluorescence proteins (mCherry) that will allow easy detection of the virus under the fluorescence microscope, or proteins that emit light (luciferase) and can be use for detection of the virus in semi-automated systems like an ELISA or even inside a mouse. Infectious clones are then very useful for studying viral protein functions, virus tropism in mosquitoes or mice, or even for performing large-scale drug (antiviral) screenings.  

UNU-BIOLAC: If Latin America had access to a full set of capabilities (Human and technological) in this area, what do you think would be the first biotechnological applications that could be achieved?

JL: Two of the main biotechnological applications in the area will be vaccine development (live attenuated vaccines) for the dengue virus and other important viruses for the region, also with RNA genomes (like Zika virus, or Mayaro virus), and in the search for active compounds with antiviral activity (either synthetic compounds, or, as is the case in the region, from natural products).  

UNU-BIOLAC: What were the most interesting research approaches that you got to know during the course last year?

JL: Course participants were interested in learning about infectious clones for multiple applications: some were interested in the identification of compounds with antiviral activities derived from plants, other for the implementation of massive diagnostic techniques, and still others, like us, in the study of viral protein functions and the identification of cell factors necessary for virus replication, which will lead to the identification of new antiviral targets.