Expression of the tick-borne encephalitis virus NS1 gene in Gram-negative bacteria from the mouse nasopharynx

Bacteria were isolated from the nasopharynx of BALB/c mice and electroporat ed with pUR290(NS1)(2) containing two copies of tick-borne encephalitis vir us (TBEV, strain Sofjin) NS1 under the control of the lac promoter. The pla smid persisted in transformants for at least ten passages. The NS1 gene exp ression was detected in Gram-negative enterobacteria by immunoblotting with monoclonal antibodies against the TBEV nonstructural glycoprotein NS1. Rec ombinant NS1 was detected in bacterial cells and in the culture medium. Int ranasal immunization with recombinant bacteria caused antibodies against NS 1 to appear in the serum of BALB/c mice. However, the humoral immune respon se to NS1 failed to protect mice from a TBEV challenge.