Abstract
Inhibitors of viral disassembly or RNA and protein synthesis, viral disassembly intermediates (infectious subviral particles, ISVP), binary ethylenimine-inactivated virions, and viral particles lacking genomic double-stranded (ds) RNA (empty particles) were used to assess the expression of interleukin-1β (IL-1β) mRNA in chicken (chIL-1β) macrophages in response to avian reovirus. The results demonstrate that two distinct expression patterns of chIL-1β mRNA mediated by different steps in viral replication were found. Viral disassembly was required for the induction of a rapid, transient expression pattern of chIL-1β mRNA that was rapidly induced at 30 min, with maximal levels reached by 2 h, and fell to a low level within 6 h post-inoculation, while viral RNA synthesis rather than protein translation, which was subsequent to membrane penetration, was required to induce a stable, sustained expression pattern of chIL-1β mRNA that occurred at and after 6 h post-inoculation. In addition, the induction of chIL-1β mRNA expression by the empty particles and ISVP was extremely weak, compared with the active dsRNA+ virions or binary ethylenimine-inactivated virions, suggesting that the presence of dsRNA, even if transcriptionally inactive, may be an important factor in this response.
Oligonucleotide primers used for RT-PCR in this study are available with the online version of this paper.