A method for rapid and high-yield production of the tick-borne encephalitis virus E and DIII recombinant proteins in E. coli with preservation of the antigenic properties

Tick-borne encephalitis virus (TBEV) is a member of the Flavivirus genus and is the main pathogenic arbovirus circulating in Europe, Russia and China. The envelope (E) protein is exposed on the viral surface and is the main antigen that is employed in diagnostic tests based on the detection of protein-specific antibodies from serum samples of infected individuals. The high degree of similarity among the E proteins of flaviviruses can, in some cases, lead to cross-reactivity and false-positive results in serological tests. Increased specificity in the detection of positive sera for different Flavivirus infections is often obtained by using a portion of the E protein, namely, the DIII domain. Different strategies and expression systems have been described for E and DIII protein production. Here, we present the optimization of an easy and fast method for TBEV E and DIII antigen production and partial purification from E. coli inclusion bodies. The antigenic properties of the produced antigens are retained, as validated by ELISAs with anti-TBEV murine sera as well as sera from infected human patients. The potential applications of both proteins as diagnostic reagents were confirmed.