According to a recent study, up to 390 million people are infected with Dengue virus (DENV) each year throughout the world, with 25% developing a clinical illness. The study, which examines the complicated dynamics of DENV, emphasizes the role that different immune responses have in creating dengue outbreaks. Â
The Aedes mosquito carries both DENV and ZIKV, and this study investigates the links between the two viruses. In 2013 and 2014, ZIKV merged with DENV hotspots in Latin America. Antibody-dependent enhancement (ADE) is a mechanism in which some people who have been exposed to DENV or ZIKV develop permanent immunity. Still, others have minimal protection against subsequent infections and illnesses. Â
Several models have been created to describe the cyclical and chaotic character of dengue outbreaks in endemic nations. Rather than measuring the number of infections a person has had, the authors of this study propose a unique SIRS-type model that measures immunity using antibody titer. This unique technique will investigate the influence of repeated dengue virus exposure on disease spread. Â
Although it was previously considered that immunity could be maintained even after two or four infections, new immunological studies have questioned this long-held belief. According to the findings, the presence of viremia and a decrease in antibody titers following a second infection indicate homologous DENV reinfections. Future DENV infection can be decreased by building immunity through repeated exposure to the same or a different serotype. Â
The study uses data from Nicaragua, where DENV and ZIKV outbreaks have occurred. By reconstructing the model using estimates from antibody titers acquired in Nicaraguan cohorts, the researchers show that huge increases and declines in antibody titers occur during big Zika and dengue epidemics, particularly in highly exposed groups, including adults. Â
These findings call into question the concept of permanent immunity and give a more complex picture of dengue dynamics. The findings reveal a link between low dengue case rates and increased community risk due to diminishing immunity in formerly immune groups. This increasing vulnerability will almost certainly result in significant dengue epidemics in the coming years. Â
The findings of this study might have consequences for the dengue vaccine in the future. Despite the fact that current immunizations give excellent protection for seropositive children, the findings of this study show that boosters may be required to maintain optimal protective immunity and avert outbreaks. Potential interactions between mosquito-borne viruses, such as the effect of Zika virus infection on modifying DENV herd immunity, are also investigated. Â
Finally, the study reveals the importance of developing and declining immunity in the development of dengue epidemics, revealing the intricate dynamics of DENV. The findings provide light on the complex link between the human immune response and viral transmission, leading to better dengue control techniques. Â
Journal Reference Â
Aogo, R. A., Zambrana, J. V., Sanchez, N., Ojeda, S., Kuan, G., Balmaseda, A., … Katzelnick, L. C. (2023). Science Translational Medicine, 15(722). doi:10.1126/scitranslmed.adi1734Â
