PASSIVE AND PROTECTIVE IMMUNITY IN DUCKLINGS ELICITED BY A PARVOVIRUS SUBUNIT VACCINE WITH CpG ADJUVANT

We previously demonstrated that ducks immunized with recombinant VP2 protein (rVP2) of parvovirus in conjunction with CpG oligodeoxynucleotides (ODN) containing three copies of GACGTT motifs had significantly ([Formula: see text]) increased antibody titer, splenocyte proliferation index, amount of CD4[Formula: see text] and CD8[Formula: see text] cells, and mRNA expression of cytokines (IFN-[Formula: see text], IFN-[Formula: see text], IL-6, and IL-8) in comparison with those immunized with rVP2 plus aluminum hydroxide. In the present study, ducklings hatched from eggs produced by ducks immunized with rVP2 and various adjuvants were used to analyze the passive immunity of maternal antibodies followed by an experimental challenge with live parvovirus. Results indicated that the titer of VP2-specific antibodies and the body weight of ducklings produced from ducks immunized with rVP2[Formula: see text]CpG ODN were significantly ([Formula: see text]) higher than those of ducklings from other groups at day 7 after the challenge. The autopsy report revealed that ducklings in groups other than rVP2[Formula: see text]CpG ODN and rVP2[Formula: see text]mock had hemorrhage in the liver and intestinal mucous at 11 days after the challenge, and the presence of parvovirus was confirmed by PCR using parvovirus-specific primers. Therefore, immunizing ducks with rVP2[Formula: see text]CpG ODN containing three copies of GACGTT motifs is able to enhance the passive immunity, which protects their ducklings from parvovirus infection.