Vitellogenin is an acute phase protein with bacterial-binding and inhibiting activities.

Previous studies have shown that vitellogenin (Vg) is an immune-relevant molecule, but its potential immunological role in vivo remains obscure. We demonstrated here that injection of lipopolysaccharide (LPS) and lipoteichoic acid (LTA) into male Danio rerio rapidly induced a significant up-regulation of Vg at both transcriptional and translational levels, and that serum Vg produced was able to bind to both Escherichia coli and Staphylococcus aureus and to inhibit their growth in a dose-dependent manner. All these data suggest that serum Vg in zebrafish D. rerio is an acute phase protein with bacterial-binding and inhibiting activities. It also bolsters the notion that factors normally involved in control of female reproduction are linked with immunity in organisms that rely on Vg for oocyte development.