A new class of antibodies is capable of neutralizing all 4 forms of dengue virus, which causes an estimated 400 million infections annually and can lead to shock, hemorrhage, and death (Dejnirattisai W et al. Nat Immunol. doi:10.1038/ni.3058 [published online December 15, 2014]).
Although infection with 1 form of the virus leads to lifelong protection against that specific form, it does not protect against (and can often enhance the severity of) secondary infection by one of the other 3.
Hampton T. Antibody Class Neutralizes Multiple Forms of Dengue Virus. JAMA. 2015;313(5):455. doi:10.1001/jama.2015.47