Tick-borne encephalitis (TBE) virus causes severe encephalitis with serious sequelae in humans. An epizootiological survey of wild rodents is effective to detect TBE virus-endemic areas; however, limited serological diagnostic methods are available to detect anti-TBE virus antibodies in wild rodents. In this study, ELISAs for the detection of rodent antibodies against the TBE virus were developed using two recombinant proteins, domain III of the E protein (EdIII) and subviral particles (SPs), as the antigens. As compared with the neutralization test, the ELISA using EdIII had 77.1% sensitivity and 80.0% specificity, and the ELISA using SPs had 91.4% sensitivity and 100% specificity. Furthermore, when the ELISAs were applied to the epizootiological survey in the TBE virus-endemic area, both of the ELISAs was able to detect wild rodents with TBE virus-specific antibodies. This is the first study to show that ELISAs using recombinant antigens can be safe and useful in the detection of TBE virus-infected wild rodents in epizootiological research.Key words E protein, epizootiology, rodents, subviral particles, tick-borne encephalitis.The tick-borne encephalitis (TBE) virus, which belongs to the genus Flavivirus within the family Flaviviridae, causes severe encephalitis with serious sequelae in humans (1). The TBE virus occurs widely across Europe, Russia and Far-Eastern Asia, including Japan (2-6), and more than 10 000 cases of the disease are reported annually. The TBE virus has been subdivided into three subtypes: the far-eastern subtype known to cause Russian spring-summer encephalitis in Russia, the western European subtype known to cause Central European encephalitis in many European countries, and the Siberian subtype. The TBE virus has a significant impact on public health in the endemic regions.The prevalence of the TBE virus in nature depends on the transmission cycles of the interactions among List of Abbreviations: ALP, alkaline phosphatase; DDW, deionized, distilled water; EdIII, domain III of the E protein; OD, optical density; PBST, phosphate-buffered saline containing 0.05% Tween 20; prM, precursor M; P-N, positive-negative difference; RSSE, Russian spring-summer encephalitis; SP, subviral particle; TBE, tick-borne encephalitis.the viruses, their vector ticks and their vertebrate hosts (7). The Ixodes ticks are primary tick vectors that play a crucial role in maintaining the transmission cycle of the TBE virus. The major tick vector for the far-eastern subtype and the Siberian subtype is Ixodes persulcatus and that for the western European subtype is I. ricinus. The most important vertebrate hosts for the TBE virus are rodents that have the highest population densities within an endemic focus (generally Apodemus, Clethrionomys or Microtus species).For the control of the TBE virus infection, it is important to specify the TBE virus-endemic area and design an effective vaccination plan. An epizootiological survey of field rodents is effective in the detection of TBE virusendemic areas; however, l...