The immunogenicity of DNA constructs co-expressing GP5 and M proteins of porcine reproductive and respiratory syndrome virus conjugated by GPGP linker in pigs
Journal
Veterinary Microbiology
Journal Volume
146
Journal Issue
3-4
Pages
189-199
Date Issued
2010
Author(s)
Chia, M.-Y.
Hsiao, S.-H.
Chan, H.-T.
Huang, P.-L.
Tsai, Y.-C.
Lin, C.-M.
Abstract
The heterodimer of glycoprotein 5 (GP5) and non-glycosylated matrix protein (M) is the leading target for the development of new generation of vaccines against porcine reproductive and respiratory syndrome virus (PRRSV) infection. It has been demonstrated that DNA vaccine co-expressing GP5 and M proteins as a fusion protein aroused better immunogenicity than that expressing GP5 or M alone, but it was no better than the DNA vaccine co-expressing GP5 and M proteins with two different promoters. Altered natural conformation of the co-expressed GP5 and M fusion protein was considered as the major cause. Glycine-proline-glycine-proline (GPGP) linker can minimize the conformational changes in tertiary structure and provide flexibility of the peptide chain. The objective of this study was to evaluate whether the immunogenicity of DNA constructs co-expressing GP5 and M proteins linked by GPGP could be enhanced in pigs. Three recombinant DNA constructs expressing GP5/M fusion protein without GPGP linker (pcDNA-56), GP5/M fusion protein conjugated by GPGP linker (pcDNA-5L6), and M/GP5 fusion protein conjugated by GPGP linker (pcDNA-6L5) were established. Sixteen PRRSV-free pigs were randomly assigned to four groups and inoculated intramuscularly with 3 consecutive doses of 500μg of empty vector pcDNA3.1, pcDNA-56, pcDNA-5L6 or pcDNA-6L5 each at a 2-week interval followed by challenge with 5×105 TCID50 PRRSV at 3 weeks after the final inoculation. All pcDNA-56-, pcDNA-5L6-, and pcDNA-6L5- but not pcDNA-3.1-inoculated pigs developed neutralizing antibodies (NAs) 3 weeks after the final inoculation and a gradual increase in NA titers after PRRSV challenge, indicating that pigs inoculated with these DNA constructs could establish a sufficient immune memory. The pcDNA-5L6- and pcDNA-6L5-inoculated pigs displayed lower level and shorter period of viremia and lower tissue viral load following PRRSV challenge than did the pcDNA-56-inoculated pigs. The strategy of co-expressing GPGP-linked GP5 and M fusion protein may be a promising approach for future PRRSV vaccine development, possibly via the improvement of natural conformation of the target fusion protein. ? 2010 Elsevier B.V.
Subjects
GP5/M heterodimers; GPGP linker; Pigs; PRRSV
SDGs
Other Subjects
DNA vaccine; glycine; glycoprotein P; glycoprotein P 5; hybrid protein; M protein; proline; unclassified drug; animal experiment; Arterivirus; article; DNA immunization; expression vector; immunogenicity; molecular cloning; nonhuman; nucleotide sequence; porcine reproductive and respiratory syndrome; protein conformation; protein expression; protein tertiary structure; recombinant plasmid; viremia; virus load; 5'-Guanylic Acid; Animals; Antibodies, Neutralizing; Antibodies, Viral; Plasmids; Porcine Reproductive and Respiratory Syndrome; Porcine respiratory and reproductive syndrome virus; Swine; Vaccines, DNA; Viral Envelope Proteins; Viral Load; Viral Matrix Proteins; Viral Vaccines; Viremia; Porcine respiratory and reproductive syndrome virus; Suidae
Type
journal article