Effect of the Glycine-rich region deleted PPV VP2 to the VLPs

Abstract:

The N-terminal of porcine parvovirus (PPV) viral protein 2 (VP2) links a glycine-rich domain which is a cleavage site of PPV VP3.In order to confirm that the glycine-rich domain was essential for the self-assembling of virus-like particles (VLPs).The VP2 gene with glycine-rich domain deleted and the complete VP2 gene were inserted to eukaryotic expression vector pCI-neo and were named pCI-△VP2 and pCI-VP2. Then, pCI-△VP2, pCI-VP2 and pCI-neo were transferred into Vero Cells by liposome and the VLPs was detected by SDS-PAGE, Western blotting, indirect immunofluorescence and immunoelectron microscopy. Furthermore, 56 female Kunming mice were divided into 5 groups and injected intramuscularly with pCI-△VP2, pCI-VP2 and pCI-neo as DNA vaccine, PPV inactivated vaccine and normal saline separately. The peripheral blood of the mice was collected to analyze the subgroups of the peripheral blood mononuclear cell by flow cytometry, to detect the antibody and lymphocyte proliferation by indirect-ELISA and MTT assay separately. The results show that the VLPs were observed both in the pCI-△VP2 and pCI-VP2 transferred Vero Cells. The two VLPs could agglutinate guinea pig erythrocytes. The results also show that both the pCI-△VP2 and pCI-VP2 vaccine induced special cellular and humoral immunity effectively. Those results revealed that the glycine-rich domain is not essential for the VPL’s self-assembling. This study provides a new theoretical evidence for the relationship between the gene structure and protein function of VP2.