Heterotypic Serologic Responses after Yellow Fever Vaccination; Detection of Persons with Past St. Louis Encephalitis or Dengue

Abstract

Antibody responses after 17D yellow fever (YF) vaccination in persons with no known previous arbovirus infection or only prior vaccination, were compared with similar measurements in those who had recovered from St. Louis encephalitis (SLE) or dengue. All of the eight subjects infected with SLE virus 20 to 69 months before, and five of eight with dengue six to 19 months earlier had a broad heterotypic hemagglutination-inhibiting (HI) antibody response to all eight antigens used, whereas the nine uninfected and the six prior vaccinated individuals developed HI antibodies to YF alone. Three persons with past dengue but with no changes in HI antibody titer after vaccination, had prevaccination HI antibody titers of 1:40 or more to at least one of the arbovirus antigens; only one of the five dengue subjects with HI antibody increases had prevaccination titers of this level. By contrast, the prevaccination titers in persons who had recovered from SLE infection were unrelated to their subsequent serologic responses. In addition to a heterotypic response, those who had recovered from both diseases had a greater homotypic response than did the others. HI antibodies to group B arboviruses were measured in 38 Miccosukee Indians of South Florida before and after 17D yellow fever vaccination. Initially, antibodies were present in only three individuals. Following vaccination all Indians showed a YF response and 14 developed a heterotypic response similar to that of persons with past SLE infection and dengue. The CF antibody responses after vaccination in general followed the same pattern as the HI responses but were at considerably low levels and were more variable. There was no firm correlation with prior group B arbovirus exposure and heterotypic CF responses. It is concluded that YF vaccination is a potent tool to recall past elevated HI titers of SLE and dengue antibodies for epidemiologic purposes in order to detect populations in which outbreaks of group B arbovirus infections have previously occurred and may recur.