Analysis of the swine tracheobronchial lymph node transcriptomic response to infection with a Chinese highly pathogenic strain of porcine reproductive and respiratory syndrome virus

Laura C Miller,Kay S Faaberg,Darrell O Bayles,Jamie N Henningson,Kelly M Lager,Andrew Arbogast,Marcus E Kehrli,Han-Chun Yang,Damarius Fleming,Sarah N Schlink,Baoqing Guo

doi:10.1186/1746-6148-8-208

Abstract

BackgroundPorcine reproductive and respiratory syndrome virus (PRRSV) is a major pathogen of swine worldwide. Emergence in 2006 of a novel highly pathogenic PRRSV (HP-PRRSV) isolate in China necessitated a comparative investigation into the host transcriptome response in tracheobronchial lymph nodes (TBLN) 13 days post-infection with HP-PRRSV rJXwn06, PRRSV strain VR-2332 or sham inocula. RNA from each was prepared for next-generation sequencing. Amplified library constructs were directly sequenced and a list of sequence transcripts and counts was generated using an RNAseq analysis pipeline to determine differential gene expression. Transcripts were annotated and relative abundance was calculated based upon the number of times a given transcript was represented in the library.ResultsMajor changes in transcript abundance occurred in response to infection with either PRRSV strain, each with over 630 differentially expressed transcripts. The largest increase in transcript level for either virus versus sham-inoculated controls were three serum amyloid A2 acute-phase isoforms. However, the degree of up or down-regulation of transcripts following infection with HP-PRRSV rJXwn06 was greater than transcript changes observed with US PRRSV VR-2332. Also, of 632 significantly altered transcripts within the HP-PRRSV rJXwn06 library 55 were up-regulated and 69 were down-regulated more than 3-fold, whilst in the US PRRSV VR-2332 library only 4 transcripts were up-regulated and 116 were down-regulated more than 3-fold.ConclusionsThe magnitude of differentially expressed gene profiles detected in HP-PRRSV rJXwn06 infected pigs as compared to VR-2332 infected pigs was consistent with the increased pathogenicity of the HP-PRRSV in vivo.

Highlights

Porcine reproductive and respiratory syndrome virus (PRRSV) is a major pathogen of swine worldwide
The magnitude of differentially expressed gene profiles detected in HP-PRRSV rJXwn06 infected pigs as compared to VR-2332 infected pigs was consistent with the increased pathogenicity of the HP-PRRSV in vivo
This question was resolved when porcine high fever disease (PHFD) was reproduced in China with virus derived from an infectious clone of the JX143 PRRSV isolate [18] demonstrating that PRRSV isolates with a common genetic motif had a causal role in PHFD leading to this lineage of virus being called highly pathogenic PRRSV (HP-PRRSV)

Summary

Introduction

Porcine reproductive and respiratory syndrome virus (PRRSV) is a major pathogen of swine worldwide. Emergence in 2006 of a novel highly pathogenic PRRSV (HP-PRRSV) isolate in China necessitated a comparative investigation into the host transcriptome response in tracheobronchial lymph nodes (TBLN) 13 days post-infection with HP-PRRSV rJXwn, PRRSV strain VR-2332 or sham inocula. There was still a question as to whether there was some unknown agent in the PRRSV preparations that increased the severity of the clinical disease over what was expected for a “routine” PRRSV infection This question was resolved when PHFD was reproduced in China with virus derived from an infectious clone of the JX143 PRRSV isolate [18] demonstrating that PRRSV isolates with a common genetic motif had a causal role in PHFD leading to this lineage of virus being called highly pathogenic PRRSV (HP-PRRSV). The objective of this report was to investigate gene expression profiles in porcine tracheobronchial lymph node (TBLN) during viral infection with HP-PRRSV rJXwn strain alongside of US PRRSV strain VR-2332 at a snapshot of 13 days post-infection using bioinformatics

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