Targeting Host Proteins to Impede Rabies Virus (RABV) Replication: Insights into FAK, Hsp90, and Cdc37 Inhibition

Background: In the 21st century, the deadly viral disease rabies continues to claim victims. After entering the cell, the rabies virus (RABV) utilizes growth and transcription factors or certain cell proteins to evade the immune system. Focal adhesion kinase (FAK) is an essential intracellular kinase that positively interacts with the rabies phosphoprotein, which is not only a multifunctional protein with transcription and replication activity but also an interferon (IFN) antagonist, benefiting the RABV. It has been proven that heat shock protein 90 (Hsp90), a crucial cellular chaperone, along with cell division cycle 37 (Cdc37), a co-chaperone of Hsp90 that can function independently, are involved in the maturation, stabilization, and activation of the RABV. When the RABV infects the cell, it exploits FAK, Hsp90, and Cdc37 for its survival and replication. Objectives: This study aims to eliminate the positive effects of FAK, Hsp90, and Cdc37 on the RABV to increase the survival time of RABV-infected cells. Methods: We investigated the effect of FAK inhibition with PF-573,228 and the prevention of Hsp90 or Cdc37 protein expression with shRNAs on the rabies P protein in infected cells. Techniques used in our research included MTT assay, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and Western blot analysis. Results: The results showed a robust decrease in P protein and the titer of the RABV in cells treated with PF-573,228 or transfected with Hsp90 and Cdc37 ShRNAs. However, this did not lead to the complete elimination of P protein expression, indicating that FAK, Hsp90, and Cdc37 are not the only factors the RABV uses for reproduction and survival. Conclusions: According to our results, FAK has the most significant association with rabies P protein during replication, followed by Hsp90 and Cdc37, respectively.