Serological cross-reactive responses against heterologous FMDVs. A two-dimensional (2D) virus neutralization test was performed using sera from six cows vaccinated with the rHN, rHN/NXVP1 or rHN/TURVP1 vaccine at 28 dpv. The dotted line indicates the cut-off value of 0.3. Three experiments were performed independently, and the mean r1 values were obtained from three replicates of six animals. Error bars indicate SDs from the mean.