Children who have experienced multiple cases of dengue virus develop a robust army of dengue-fighting T cells, according to a groundbreaking study led by scientists at the La Jolla Institute for Immunology (LJI). This research, published in JCI Insights, suggests these T cells are essential in building immunity against the dengue virus. Children who have experienced two or more dengue infections are far less likely to show significant symptoms upon subsequent infections, highlighting the role of T cells in viral immunity.

Dengue virus, which infects up to 400 million people annually, has no widely available therapies or vaccines. As the virus spreads into new regions, including Southern California, the urgency to develop effective vaccines and treatments has become critical. In 2023, California reported its first-ever case of locally acquired dengue virus, with Los Angeles County reporting 12 additional cases and San Diego County confirming two. The expansion of dengue into areas where the population has not previously been exposed changes the dynamic of the virus’s impact and the need to develop effective vaccines.

“Dengue virus is expanding into areas where the majority of people have never seen the virus,” said Weiskopf, a member of LJI’s Center for Vaccine Innovation. “That will change the game.”

In their study, scientists at LJI aimed to understand the role of T cells in managing dengue virus infection. The immune system must carefully balance its response to the virus to avoid complications. A weak T cell response can make combating infection difficult, while an aggressive response can lead to harmful inflammation and potentially fatal complications.

Researchers studied 71 children in Managua, Nicaragua, a region endemic to dengue virus. Since 2004, Eva Harris, Ph.D., Director of the Center for Global Public Health at UC Berkeley, has collaborated with Nicaraguan scientists to study dengue infections in this cohort. By regularly monitoring the children’s antibodies and responses, researchers can detect dengue exposure.

It was discovered that the number of dengue-fighting T cells in these children increased with each infection, leading to better management of subsequent infections. Children with multiple dengue infections were significantly less likely to exhibit clinical symptoms, while those infected only once had a higher chance of showing symptoms during a later infection. Overall, this data show strong evidence that T cells may help reduce severity during different types of mosquito-borne viruses, not just dengue.

“There’s a lot more work to be done,” said Weiskopf, emphasizing the need for continued research into harnessing T cells’ power to combat dengue virus. Weiskopf’s team is not alone in this endeavor. Many institutions across the United States and globally are collaborating to fight this growing threat. For example, in Florida, researchers from the University of Florida and the Florida Department of Health are working to develop a local T cell-based vaccination strategy to supplement current prevention techniques, emphasizing the practical use of local troop to manage the virus.

As dengue continues to spread, it is critical to understand that this viral threat does not discriminate and can affect anyone, regardless of age or location. From the Hawaii and Florida facing dengue outbreaks in the past, the threat was contained—so we know it is possible.

Public Health Implications and Community Efforts

The spread of dengue in California underscores the need for community vigilance. Community education programs, such as those run by the Los Angeles County Department of Public Health, aim to educate residents on mosquito-prevention strategies, including the use of repellents, removing standing water, and wearing protective clothing. For California, whose climate aligns with the dengue-carrying mosquito genus Aedes —common in equatorial climates, it is critical to understand.

While the study publications indicate promising advancements, it is essential to remain cautious and address potential criticisms. Skeptics may argue that potential vaccines could be as costly as ever, particularly as we embark on the age of the coronavirus pandemic. Moreover, we must consider the potential side effects of the vaccines themselves, which may involve long-term complications.

La Jolla Institute of Immunology is amongst a long list of reserarch centers within the US investing locally and internationally to find out what cutting-edge science can tell us about real-world applications, and dengue is pushing the leading edge.