Abstract

A fusion gene encoding glycoprotein 5 (GP5) of porcine reproductive and respiratory syndrome virus (PRRSV) truncated trans-membrane regions was constructed successfully through a linker-based reconstruction strategy and overlap polymerase chain reaction (PCR). High-level expression of the truncated GP5 protein with a molecular weight of 16 kDa was obtained in Escherichia coli BL21 (DE3) through subcloning of the gene into a prokaryotic expression vector pET-28a. Western blot indicated that the truncated GP5 protein could react specifically with pig positive serum against PRRSV and anti-His₆ mAb, respectively. After recovering from inclusion bodies through nickel affinity purification and refolding by gradient dialysis, the truncated GP5 protein showed high specific reaction to the PRRSV positive serum in enzyme-linked immunosorbent assay (ELISA) and was used to immunize BALB/c mice. Immunoperoxidase monolayer assay (IPMA) indicated that mouse polyclonal antibody could react apparently with MARC-145 cells infected with PRRSV as pig positive serum against PRRSV did. Thus, the truncated GP5 was demonstrated to have good immunogenicity and would be very useful for PRRSV antibody detection as well as for vaccine development.

Key words: Overlap polymerase chain reaction (PCR), truncated GP5 protein, heterologous expression, immunogenicity.