Identification of host proteins that interact with non-structural proteins-1α and -1β of PRRSV-1

Porcine reproductive and respiratory syndrome viruses (PRRSV) are responsible for the most important infectious disease affecting the global pig industry, causing respiratory disease in piglets and reproductive failure in sows. Both species of PRRSV (PRRSV-1 and −2) are rapidly evolving and existing vaccines are failing to control the PRRS panzootic. PRRSV produces 16 non-structural proteins (NSPs) that are involved in viral replication and/or modulating the host immune response. Previous studies have shown that PRRSV NSP1α and NSP1β modulate host cell responses; however, the underlying molecular mechanisms remain to be fully elucidated. PRRSV-1 strains predominate in Europe but have been studied far less than PRRSV-2, therefore, this project aims to identify and characterise novel PRRSV-1 NSP1-host protein interactions. NSP1α and NSP1β from a representative PRRSV-1 subtype 1 strain (215-06) were screened using the yeast-2-hybrid (y-2-h) system and a cDNA library generated from porcine alveolar macrophages – the primary target cell of PRRSV-1. The screens identified 62 and 127 putative binding partners for NSP1α and NSP1β, respectively. Potential binding partners involved in IFN signalling, the NF-κB pathway, ubiquitination and nuclear transport have been selected for confirmation and characterisation. Identifying and characterising these novel interactions will increase our understanding of how PRRSV-1 NSP1α/β modulates the host cellular immune response, which could subsequently be exploited to rationally attenuate PRRSV-1 as a basis for improved vaccines.