The goose parvovirus (GPV) Rep1 protein is both essential for viral replication and a potential target for GPV
diagnosis, but its protein characterization and intracellular localization is not clear. We constructed a recombinant plasmid,
pET28a/GPV-Rep1, and expressed the Rep1 gene in BL21 (DE3) Escherichia coli. A protein approximately 75 kDa
in size was obtained from lysates of E. coli cells expressing the recombinant plasmid. SDS-PAGE analysis showed that after
induction with 0.6 mM isopropyl β-D-thiogalactosidase (IPTG) at 30°C for 5 h, the Rep1 protein was highly overexpressed.
Two methods used to purify proteins, a salinity-gradient elution and Ni-NTA affinity chromatography, were performed.
The amount of Rep1 protein obtained by Ni-NTA affinity chromatography was 41.23 mg, while 119.9 mg of
Rep1 protein was obtained by a salinity-gradient elution from a 1 L E. coli BL21 (DE3) culture. An immunogenicity
analysis showed that the protein could significantly elicit a specific antibody response in immunized goslings compared to
control groups. Antibody titers peaked to 1:5120 (optical density (OD) 450 = 3.9) on day 28 after immunization but had
mean titers of 1:10,240 (OD450 = 4.2) in gosling groups immunized with a commercially available GPV-attenuated vaccine
strain. Experiments examining subcellular localization showed that the Rep1 protein appeared to associate predominantly
with the nuclear membrane, especially during later times of infection. This work provides a basis for biochemical
and structural studies on the GPV Rep1 protein.