Date Full Report Received06/04/2008
Date Abstract Report Received06/04/2008
Funded ByNational Pork Board
Porcine Reproductive and Respiratory Syndrome (PRRS) affects porcine industry globally and brings a significant economic loss in the agricultural sector. It is reported that both European and North American strains of PRRSV circulate in respective local pig farms. Although several PRRS vaccines, including both modified Lelystad virus and killed virus, are currently available in the market, the efficacy of these vaccines is mainly based on the genetically diverged field strains of PRRSV and do not confer protection against a virulent heterologous strain. Specific vaccine against designated strains maybe a solution, but it is found that some strains of PRRSV isolated from field failed to propagate in cell culture making the vaccine production difficult. In this project a PRRSV-susceptible cell-line derived from African green monkey kidney cell, MARC-145, are modified to enhance the susceptibility to various strains of PRRSV and thus the propagation efficiency of the virus. The cells were transfected with porcine sialoadhesin, recently shown to be a putative PRRSV receptor. These modified cells were infected with locally isolated PRRSV strains and the replication efficiency will be assessed and evaluated. Both EU and NA PRRSV strains were employed in the experiment. The result shows that expression of porcine sialoadhesin in MARC-145 cells did not facilitate a higher proliferation rate than in the wild-type MARC-145 cells. The reason may be due to that the virus strains used in the experiments propagate well in the MARC-145, therefore the enhancement brought by the addition of sialoadhesin may not be significantly shown. To further characterize the effect of porcine sialoadhesin in MARC-145, a virus strain that cannot grow well in MARC-145 should be isolated and employed in this experiment. Nevertheless, successful transformant may still provide an insight into vaccine production against specific PRRSV strains.