Albinsson et al.
Antibody responses to tick-borne encephalitis virus non-structural protein 1 and whole virus-antigen – a new tool in the assessment of suspected vaccine failure patients
Infect. Ecol. Epidemiol. 2019, 9:1, 1696132, doi: 10.1080/20008686.2019.1696132

TBE vaccines are highly effective. However, vaccine failures have been reported (e.g. see Snapshot week 10/2020). The detection of antibodies directed to TBE virus non-structural protein 1 (NS-1) and/or to the envelope protein (and other structural viral antigens) may help to discriminate, if a patient has developed disease caused by a viral infection (despite vaccination) or if the antibody response is (only) directed to vaccine antigens. NS-1 is not part of the commercially available (killed whole virus) vaccines containing only structural antigens, and thus, vaccinees do not develop antibodies to NS-1.

A Swedish group has analyzed 17 serum samples and 18 CSF samples from 14 patients who had a documented history of TBE vaccination but had clinical and laboratory suspected TBE virus infections. 11 out of 14 patients were found IgM antibody positive to NS-1 in serum or CSF, while all patients tested positive for whole virus antigen. The positive test for NS-1 indicate a current or recent TBE virus infection and testing for NS-1 antibodies may help to identify vaccine failures.

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