Figure 1.

Humoral immune response. Serum samples collected at different time points (weeks 2, 6 and 13) were tested using Plaque‐Reduction Neutralization Test (PRNT). Each serum sample was tested with either the Orthopoxviruses (OPV) Abatino (circle) or the LV reference vaccinia strain (triangle). The PRNT titre was assessed as the serum dilution causing 50% PFU reduction compared with the PFU of virus controls, using the Reed and Muench method for calculation. Serial twofold dilutions of sera were used