Screening of PRRSV- and ASFV-encoded proteins involved in the inflammatory response using a porcine iGLuc reporter

摘要

Inflammasome plays a major role in innate immune responses by activating caspase-1, resulting in secretion of interleukin-1 beta (IL-1 beta) and inflammatory pathologic responses. IL-1 beta release is widely used as an indirect readout to study inflammasome activation. Here we report an iGLuc reporter (pro-IL-1 beta-Gluc) of pig origin to monitor cytosolic pro-IL-1 beta cleavage and mature IL-1 beta release. Based on the iGLuc reporter, we reconstructed the inflammasome system in vitro and screened PRRSV- and ASFV-encoded proteins involved in regulating inflammasome activation. We found that three non-structural proteins (nsps) of PRRSV, nsp1 beta, nsp2 and nsp5, activate the NLRP3 inflammasome, and four nsps of PRRSV, nsp1 alpha, nsp7, nsp10 and nsp11, inhibit NLRP3 inflammasome activation, of which nsp10 and nsp11 have a highly significant inhibitory effect. In addition, we also found that four ASFV-encoded proteins, S183L, E199L, 061R and I7L activate the inflammatory response and four ASFV-encoded proteins, I226L, A151R, NP419L and QP383R, inhibit the inflammatory response. Our results provide a highly sensitive and high-throughput tool to screen for proteins that regulate inflammasome activation in vitro.