Abstract
Both virulent and live-attenuated porcine reproductive and respiratory syndrome virus (PRRSV) strains can establish persistent infection in lymphoid tissues of pigs. To investigate the mechanisms of PRRSV persistence, we performed a transcriptional analysis of inguinal lymphoid tissue collected from pigs experimentally infected with an attenuated PRRSV strain at 46 days post infection. A total of 6404 differentially expressed genes (DEGs) were detected of which 3960 DEGs were upregulated and 2444 DEGs were downregulated. Specifically, genes involved in innate immune responses and chemokines and receptors associated with T-cell homing to lymphoid tissues were down regulated. As a result, homing of virus-specific T-cells to lymphoid tissues seems to be ineffective, evidenced by the lower frequencies of virus-specific T-cell in lymphoid tissue than in peripheral blood. Genes associated with T-cell exhaustion were upregulated. Likewise, genes involved in the anti-apoptotic pathway were upregulated. Collectively, the data suggested that the live-attenuated PRRSV strain establishes a pro-survival microenvironment in lymphoid tissue by suppressing innate immune responses, T-cell homing, and preventing cell apoptosis.
Highlights
Porcine reproductive and respiratory syndrome virus (PRRSV) is a positive sense, single strandedRNA virus that belongs to the family Arteriviridae, under the order Nidovirales [1]
The attenuated porcine reproductive and respiratory syndrome virus (PRRSV) strain designated CON90 used in this study was recovered from an infectious cDNA clone constructed using viral RNA extracted from the attenuated CON-P90 [27]
The results demonstrate that all five pigs in this study were persistently infected with the attenuated PRRSV strain CON90
Summary
Porcine reproductive and respiratory syndrome virus (PRRSV) is a positive sense, single strandedRNA virus that belongs to the family Arteriviridae, under the order Nidovirales [1]. Porcine reproductive and respiratory syndrome virus (PRRSV) is a positive sense, single stranded. PRRSV was originally classified into two types: type 1 or PRRSV-1, which originated in Europe, and type 2 or PRRSV-2, which originated in North America. The International Committee on Taxonomy of Viruses (ICTV) recently updated the arterivirus taxonomic structure in which PRRSV-1 and PRRSV-2 are respectively classified as two species: Betaarterivirus Suid 1 and Betaarterivirus. PRRSV infects pigs of all ages; clinical manifestations are more severe when the virus infects pregnant sows and young pigs, causing reproductive failure and respiratory distress, respectively (reviewed in [3]). PRRSV is endemic in most swine producing countries worldwide, causing significant economic losses to swine producers [4].
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