Down-regulation of proteasome 20S subunit beta 5 inhibits the intracellular replication of Rickettsia rickettsii in host cells

Abstract:

[Objective] This paper aims to explore the influence of host proteasome 20S subunit beta 5 (PSMB5) on the intracellular growth and reproduction of the Gram-negative obligate intracellular parasite Rickettsia rickettsii.[Methods] We transfected Vero and THP-1 cells with PSMB5-specific small interfering RNA (siRNA) (si-PSMB5 group), non-specific siRNA (negative control group), and solution (Mock group), respectively. Then, we verified the down-regulation of PSMB5 by RT-qPCR and Western blotting assay. Subsequently, we infected the transfected cells with R. rickettsii (multiplicity of infection=0.1) and detected R. rickettsii proliferation by light microscopy, indirect immunofluorescence staining, and RT-qPCR.[Results] Compared with the negative control and Mock control, si-PSMB5 significantly down-regulated the mRNA and protein levels of PSMB5 in host cells and R. rickettsii load in si-PSMB5-transfected cells was significantly reduced after R. rickettsii infection.[Conclusion] Down-regulation of host PSMB5 gene inhibits the intracellular growth of R. rickettsii.