Tick-borne encephalitis virus (TBEV) causes one of the most important inflammatory diseases of the central nervous system, namely severe encephalitis in Europe and Asia. Since the 1980s tick-borne encephalitis is known in Mongolia with increasing numbers of human cases reported during the last years. So far, however, data on TBEV strains are still sparse. We herein report the isolation of a TBEV strain from Ixodes persulcatus ticks collected in Mongolia in 2010. Phylogenetic analysis of the E-gene classified this isolate as Siberian subtype of TBEV. The Mongolian TBEV strain showed differences in virus titers, plaque sizes, and growth properties in two human neuronal cell-lines. In addition, the 10,242 nucleotide long open-reading frame and the corresponding polyprotein sequence were revealed. The isolate grouped in the genetic subclade of the Siberian subtype. The strain Zausaev (AF527415) and Vasilchenko (AF069066) had 97 and 94 % identity on the nucleotide level. In summary, we herein describe first detailed data regarding TBEV from Mongolia. Further investigations of TBEV in Mongolia and adjacent areas are needed to understand the intricate dispersal of this virus.

Abstract. Immediately before deployment (Fall 2012) and after deployment (Spring 2013) in support of United Nations peacekeeping operations, Mongolian Armed Forces medical personnel obtained serum samples from the first contingent of Mongolian peacekeepers deploying to South Sudan to monitor serologic evidence of exposure to diseases that cause acute febrile illness. A total of 632 paired samples were tested for IgG antibody for the following (number of seroconversions in parentheses): Rickettsia (spotted fever and typhus groups) (25), West Nile fever virus (WNV) (23), Coxiella burnetii (causative agent of Q fever) (12), dengue virus (8