*2.9. Humoral Immune Response*

The immune response to the injected constructs was assessed 10 days after the second immunization. The activity of antibodies against HCV proteins in mouse sera was determined by indirect ELISA, as described previously [30]. As secondary antibodies, we used antibodies against mouse Ig isotypes IgG1 and IgG2a conjugated to HRP (Jackson Immunoresearch Laboratories, Cambridge, UK). As the serum titer in ELISA, we used the reciprocal of the highest serum dilution, at which the optical density was 2 times higher than that for the control group.
