Flaviviruses comprise important arthropod-transmitted human pathogens, including 
yellow fever (YF), dengue (Den), Japanese encephalitis (JE), West Nile (WN) and 
tick-borne encephalitis (TBE) viruses that have the potential of expanding their 
endemic areas due to global climatic, ecological and socio-economic changes. 
While effective vaccines against YF, JE and TBE are in widespread use, the 
development of a dengue vaccine has been hampered for a long time because of 
concerns of immunopathological consequences of vaccination. Phase III clinical 
trials with a recombinant chimeric live vaccine are now ongoing and will show 
whether the enormous problem of dengue can be resolved or at least reduced by 
vaccination in the future. Unprecedented details of the flavivirus particle 
structure have become available through the combined use of X-ray 
crystallography and cryo-electron microscopy that led to novel and surprising 
insights into the antigenic structure of these viruses. Recent studies provided 
evidence for an important role of virus maturation as well as particle dynamics 
in virus neutralization by antibodies and thus added previously unknown layers 
of complexity to our understanding of flavivirus immune protection. This 
information is invaluable for interpreting current investigations on the 
functional activities of polyclonal antibody responses to flavivirus infections 
and vaccinations and may open new avenues for studies on flavivirus cell biology 
and vaccine design.