While in our study we did not identify by immunofluorescence the presence of ZPBP2 in sperm from either fertile or subfertile TB stallions, a potential confirmation of reduced zona pellucida-binding protein function in sperm from subfertile TB stallions was their reduced ability to bind to porcine ZP after incubation under capacitating conditions (Fig. 7). This evidence concerns the gene ZPBP2 and tuberculosis.