Deciphering the involvement of innate immune factors in the development of the host response to PRRSV vaccination

Abstract

The natural response of pigs to porcine reproductive and respiratory syndrome virus (PRRSV) infections and vaccinations needs to be altered so that better protection is afforded against both homologous and heterologous challenges by this pathogen. To address this problem, real-time gene expression assays were coupled with cytokine Elispot and protein analyses to assess the nature of the anti-PRRSV response of pigs immunized with modified live virus (MLV) vaccine. Although T helper 1 (Th1) immunity was elicited in all vaccinated animals, as evidenced by the genesis of PRRSV-specific interferon-gamma secreting cells (IFNG SC), the overall extent of the memory response was variable and generally weak. Peripheral blood mononuclear cells (PBMC) isolated from these pigs responded to PRRSV exposure with a limited increase in their expression of the Th1 immune markers, IFNG, tumor necrosis factor-alpha and interleukin-15 (IL15), and a reduction in the quantity of mRNAs encoding the innate and inflammatory proteins, IL1B, IL8 and IFNA. Efforts to enhance Th1 immunity, by utilizing an expression plasmid encoding porcine IFNA (pINA) as an adjuvant, resulted in a temporary increase in the frequency of PRRSV-specific IFNG SC but only minor changes overall in the expression of Th1 associated cytokine or innate immune marker mRNA by virus-stimulated PBMC. Administration of pINA, however, did correlate with decreased IL1B secretion by cultured, unstimulated PBMC but had no effect on their ability to release IFNG. Thus, while exogenous addition of IFNA during PRRSV vaccination has an impact on the development of a Th1 immune response, other alterations will be required for substantial boosting of virus-specific protection.

Transcriptome analysis of porcine PBMCs after in vitro stimulation by LPS or PMA/ionomycin using an expression array targeting the pig immune response

“…The chemokines IL8, CXCL5, CXCL3 and CXCL2 have chemotaxis for neutrophils whereas the chemokines CCL2 and CCL8 have a broader chemotaxis spectrum specific for T, dendritic and NK cells as well as monocytes and basophils [38]. Up-regulation of IL8 has already been reported in pig PBMCs [39,40] and amnion [41] after bacterial infection. In human, stimulation of PBMCs with LPS induces the secretion of CCL2 [42], CXCL3 and CXCL2 [43].…”

Salmonella entericaserovar Typhimurium-infected pigs with different shedding levels exhibit distinct clinical, peripheral cytokine and transcriptomic immune response phenotypes

“…Assays were performed in duplicate. The amplification conditions are described by Royaee et al 19 Ct values were obtained from each individual amplification curve using a standardized baseline value for each gene and averaged for each gene to determine the Ct values, as previously described. 18 Average Ct for RPL32 (housekeeping gene) in each sample was subtracted from each corresponding average target gene Ct, producing ÁCt values.…”

Immunodominant epitopes in nsp2 of porcine reproductive and respiratory syndrome virus are dispensable for replication, but play an important role in modulation of the host immune response

“…Real-time PCR for immune marker gene detection was performed as described previously (Royaee et al, 2004;Dawson et al, 2005). Samples were evaluated for expression of selected immune genes encoding targeted immune markers for innate immunity: IFN-a, IFN-b, IL-1b, IL-6, IL-8; Th1 immunity: IFN-c, IL-12b, IL-15, IL-18, TNF-a; and regulatory Tcell responses: IL-10; and the control housekeeping L32 ribosomal protein gene (RPL32).…”