Enhancement of antiviral activity of egg yolk antibodies against Chinese sacbrood virus

Chinese sacbrood virus (CSBV) poses a serious threat to the apiculture of China. Although several approaches have been attempted to control CSBV infection, their applications have been greatly limited in practical breeding of honeybees due to poor effectiveness. Egg yolk antibodies (EYA) have shown a promising protection for bees against CSBV infection. This study was conducted to produce high titer EYA and then further improve their antiviral effect. Among three vaccination groups, the EYA titer in graphene oxide-chitosan group was highest (1.591 ± 0.145), in Freund's group was modest (1.195 ± 0.040), and in white oil group was lowest (1.058 ± 0.056). After three injections of each vaccine in hens, EYA were produced at the highest level with a 14-day period. After application of EYA for more than two years in actual bee breeding, prevention and treatment assays showed that EYA confered 98.9 to 100% protection from CSBV infection. The mortality of the control group reached to a range of 91.2 to 100%. This study demonstrated that the high titer EYA have been successfully prepared with significant anti-CSBV activity and that these antibodies may feasibly be used for CSBV treatment to meet the practical needs of apiculture.