A comparison of the immune response induced by DNA or by an inactivated vaccine against tick-borne encephalitis

BALB/c mice were immunized with recombinant plasmid DNA pSVK3-ENS1 and pcDNAI-NS3 containing, respectively, genes E-NS1 and NS3 of tick-borne encephalitis (TBE) virus. Antibodies to TBE virus proteins were detected in the blood sera of the immunized animals by the method of the enzyme immunoassay. Though the titers of virus-specific antibodies in the sera of mice immunized with protein vaccines exceeded those registered after immunization with DNA vaccines, essential protective immunity was observed after the use of both vaccines.     

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

Bacteria were isolated from the nasopharynx of BALB/c mice and electroporated with pUR290(NS1)2 containing two copies of tick-borne encephalitis virus (TBEV) strain Sofjin NS1 under the control of the lac promoter. The plasmid persisted in transformants for at least ten passages. The NS1 gene expression was detected in Gram-negative enterobacteria via immunoblotting with monoclonal antibodies against TBEV nonstructural glycoprotein NS1. Recombinant NS1 was detected in bacterial cells and in the culture medium. Intranasal immunization with recombinant bacteria activated production of antibodies against NS1 in serum of BALB/c mice. The humoral immune response to NS1 failed to protect immunized mice from a TBEV challenge.     

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 electroporated with pUR290(NS1)₂ containing two copies of tick-borne encephalitis virus (TBEV, strain Sofjin) NS1 under the control of the lac promoter. The plasmid persisted in transformants for at least ten passages. The NS1 gene expression was detected in Gram-negative enterobacteria by immunoblotting with monoclonal antibodies against the TBEV nonstructural glycoprotein NS1. Recombinant NS1 was detected in bacterial cells and in the culture medium. Intranasal immunization with recombinant bacteria caused antibodies against NS1 to appear in the serum of BALB/c mice. However, the humoral immune response to NS1 failed to protect mice from a TBEV challenge.     

Interrelations between Ixodes persulcatus ticks and the tick-borne encephalitis virus of the red vole (Clethrionomys rutilis) in western Siberia

We present the data of 12-year survey (1989-2001) of the red vole population in southeastern West Siberia, including estimation of host relative numbers, abundance of immature taiga ticks, and percentage of animals with antigemagglutitnins against tick-borne encephalitis (TBE) virus. We discuss the role of demographic groups of voles as tick's hosts and their participation in the maintenance of TBE causative agent population. The estimation of spontaneous TBE infection rate in summer as well as in winter and early spring seasons, which have been made using a set of molecular-biological, serological and virological methods, demonstrates that a high proportion of red voles maintain non-pathogenic TBE causative agent over a long time, presumably, in the form of persistent infection.