Anti-TGEV Miller Strain Infection Effect of Lactobacillus plantarum Supernatant Based on the JAK-STAT1 Signaling Pathway

Wang, Kai; Ran, Ling; Yan, Tao; Niu, Zheng; Kan, Zifei; Zhang, Yiling; Yang, Yang; Xie, Luyi; Huang, Shilei; Yu, Qiuhan; Wu, Di; Song, Zhenhui

Finally, the transcriptional levels of ISGs in the Lp-1s treatment group were different at different time points. MX1 and MX2 reached their peak at 24 h, while the transcriptional levels of the two ISGs decreased at 48 h after TGEV infection. The transcription levels of PKR, ZAP, OASL and ISG15 were positively correlated in groups. We speculated that the decrease in MX1 and MX2 mRNA transcription levels within 48 h after Lp-1s treatment might be related to the cycle of infected cells. The expression of ISGs of gene silenced STAT1 decreased as a whole compared to the groups which no knock down STAT1, indicating that STAT1 could affect downstream ISGs. While the ISGs of TGEV infected group treated with Lp-1s showed an upward trend, which further confirmed that Lp-1s could activate downstream ISGs. To further explore the difference in the intracellular response of Lp-1s treated IPEC-J2 cells to TGEV infection, we detected the changes in ZAP and PKR protein levels. The level of the ZAP protein in the Lp-1s and TGEV groups was consistent with its transcription level at the time point. Although the level of the ZAP protein in Lp-1s treated cells was significantly higher than that in the TGEV infection group, the difference in the transcription level of ZAP was significantly lower than that in the TGEV infection group. These results suggested that after Lp-1s treatment, the IFN-β and JAK-STAT1 signaling pathways induced in the cells are enhanced, and the expression of the ZAP protein is still limited, suggesting that other factors have an impact on the transcriptional regulation of ZAP. The protein level of PKR was consistent with its mRNA transcription level. There was no significant difference in the p-PKR/PKR values between the two groups at 24 and 48 h; however, the p-PKR/β-tubulin protein values were in line with our expectations. The results showed that the p-PKR level in the Lp-1s group was significantly higher than that in the TGEV group, and correlated positively with time. Therefore, we believe that the increase in p-PKR is mainly determined by the expression of the PKR protein.