Yellow Fever Vaccination: Unveiling the Mechanisms Behind Strong Immune Responses

Yellow fever vaccination with the live-attenuated YF17D vaccine is renowned for its exceptional efficacy, providing long-lasting immunity with a single dose. Despite its proven success, scientists are still exploring how this vaccine induces such a robust immune response. Recent research conducted by a team led by Professor Anne Krug at Ludwig Maximilian University of Munich's Biomedical Center, in collaboration with Professor Simon Rothenfußer from LMU University Hospital, sheds light on this question.

The study focused on how specific immune cells—dendritic cells (DCs) and monocytes—react to the vaccine. Researchers analyzed these cells in the blood of over 200 healthy adults both before and after vaccination. They observed that post-vaccination, many of these immune cells exhibited activation through interferons, messenger molecules critical to antiviral defenses.

A key discovery was the increased presence of the cell surface molecule SIGLEC-1 on certain immune cells within the first week after vaccination. This molecule's upregulation was associated with the rapid development of protective antibodies against the yellow fever virus, highlighting its potential role as a biomarker for effective immune responses.

The findings suggest that interferon-induced activation of dendritic cells and monocytes plays a vital role in establishing immunity. Understanding these mechanisms not only explains the vaccine's potency but also offers insights that could aid in developing new vaccines capable of providing swift protection, especially advantageous during emerging epidemics.

This research, published in the Proceedings of the National Academy of Sciences, emphasizes the importance of innate immune responses in vaccine efficacy. The identification of SIGLEC-1 as a potential biomarker could streamline future vaccine studies and enhance our ability to predict vaccine-induced protection.

Source: https://medicalxpress.com/news/2025-05-yellow-fever-vaccination-strong-immune.html