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Updated: May 9, 2026
A Seamless Cloning Approach for Porcine Reproductive and Respiratory Syndrome Virus Expression Vector Construction
Published on: May 17, 2024
Experimental infection and comparative genomic analysis of a highly pathogenic PRRSV-HBR strain at different passage
Yanwu Wei1, Shengbin Li, Liping Huang
1Division of Swine Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, PR China.
Abstract:
A highly pathogenic strain of porcine reproductive and respiratory syndrome virus (PRRSV-HBR) was passaged on Marc-145 cells for 125 passages. In order to elucidate the change in virulence of PRRSV-HBR strain during the process of passage in vitro, swine infection experiment was performed with the viruses of low (F5 and F10) and high passage (F125). In addition, to identify the mutations related to the change in virulence of PRRSV-HBR strain, we compared and analyzed the genomic sequences of the F5, F10 and F125 of the strain. The virulence of F125 was significantly lower than that of F5 in the virus-infected pigs. In comparison with F5 and F125, there were 45 amino acids (aa) mutations and a deletion of 2 continuous aa by means of the virus genome sequence analysis. For these mutations, 33 aa (73.3%) occurred in the viral nonstructural proteins and the other 12 aa (26.7%) were contained in the viral structural proteins. Of the mutations, only 15 aa (33.3%) appeared in F10 and 30 aa (66.7%) occurred during passage from F10 to F125. The data showed that the latter 30 aa mutations were probably associated with attenuation of PRRSV-HBR strain, and that the change in virulence of the virus was determined by multiple alterations both in the structural and nonstructural genes. The virulence of PRRSV-HBR strain was remarkably attenuated after serial passages, and it can be used as vaccine candidate for control of the PRRS.
Insights
Serial passage of a highly pathogenic porcine reproductive and respiratory syndrome virus (PRRSV-HBR) in vitro significantly reduced its virulence in pigs. Genomic analysis revealed mutations likely responsible for this attenuation, suggesting its vaccine potential for PRRS control.
Area of Science:
- Virology
- Animal Health
- Molecular Biology
Background:
- Porcine reproductive and respiratory syndrome virus (PRRSV) poses a significant threat to swine health.
- Understanding PRRSV attenuation mechanisms is crucial for developing effective control strategies.
Purpose of the Study:
- To investigate the change in virulence of a highly pathogenic PRRSV strain (PRRSV-HBR) after extensive in vitro passaging.
- To identify genetic mutations associated with PRRSV-HBR attenuation.
Main Methods:
- Serial in vitro passaging of PRRSV-HBR on Marc-145 cells up to 125 passages.
- Swine infection experiments using low (F5, F10) and high (F125) passage viruses.
- Comparative genomic sequence analysis of PRRSV-HBR strains at different passage levels.
Main Results:
- The high-passage PRRSV-HBR (F125) exhibited significantly reduced virulence in pigs compared to the low-passage strain (F5).
- Genomic analysis identified 45 amino acid mutations and a 2-amino acid deletion between F5 and F125.
- A majority of mutations (73.3%) occurred in nonstructural proteins, while 33.3% of mutations appeared by F10, and 66.7% occurred between F10 and F125.
Conclusions:
- Serial in vitro passaging leads to significant attenuation of PRRSV-HBR.
- Accumulated mutations, particularly those occurring during later passages, are likely responsible for the observed attenuation.
- The attenuated PRRSV-HBR strain shows potential as a vaccine candidate for controlling PRRS.
