Autophagy enhances the replication of Peste des petits ruminants virus and inhibits caspase-dependent apoptosis in vitro

Abstract

Peste des petits ruminants (PPR) is an acute and highly contagious disease in small ruminants that causes significant economic losses in developing countries. An increasing number of studies have demonstrated that both autophagy and apoptosis are important cellular mechanisms for maintaining homeostasis, and they participate in the host response to pathogens. However, the crosstalk between apoptosis and autophagy in host cells during PPRV infection has not been clarified. In this study, autophagy was induced upon virus infection in caprine endometrial epithelial cells (EECs), as determined by the appearance of double- and single-membrane autophagy-like vesicles, LC3-I/LC3-II conversion, and p62 degradation. We also found that PPRV infection triggered a complete autophagic response, most likely mediated by the non-structural protein C and nucleoprotein N. Moreover, our results suggest that autophagy not only promotes the replication of PPRV in EECs but also provides a potential mechanism for inhibiting PPRV-induced apoptosis. Inhibiting autophagosome formation by wortmannin and knocking down the essential autophagic proteins Beclin-1 and ATG7 induces caspase-dependent apoptosis in EECs in PPRV infection. However, inhibiting autophagosome and lysosome fusion by NH4Cl and chloroquine did not increase the number of apoptotic cells. Collectively, these data are the first to indicate that PPRV-induced autophagy inhibits caspase-dependent apoptosis and thus contributes to the enhancement of viral replication and maturity in host cells.

Autophagy induction by the pathogen receptor NECTIN4 and sustained autophagy contribute to peste des petits ruminants virus infectivity

“…We previously reported that autophagy enhances PPRV replication and inhibits caspase-dependent apoptosis in vitro [37]. We also showed that the binding and entry of PPRV into EECs profoundly affects early cellular gene expression [46].…”

“…Two-way ANOVA; *P < 0.05; **P < 0.01; ***P < 0.001; # P > 0.05. strategies to manipulate autophagy and improve viral infectivity [16,51]. Moreover, we previously reported that the PPRV-H, PPRV-N and PPRV-C proteins increase LC3-II levels and highly co-localize with LC3-positive fluorescent puncta in host cells [37]. To further validate the molecular mechanisms of IRGM and HSPA1A in both PPRV-induced autophagy and viral particle formation, we first analyzed whether IRGM interacted with viral proteins in host cells.…”

“…Vaccine delivery/attenuated MeV infection induces a specific pathway of early autophagy induction involving CD46 (CYT-1)-GOPC, which initiates autophagosome formation by interacting with BECN1 [17]. Increasing evidence suggests that several members of the Morbillivirus genus, including MeV [33], CDV [35] and PPRV [36,37], can utilize an autophagic mechanism to facilitate replication. Importantly, several MeV proteins have been reported to be able to interact with autophagy-associated proteins, which could contribute to modulation of the late wave of autophagy [16,38,39].…”

“…Nevertheless, Morbillivirus species have evolved molecular strategies to counteract autophagy, escaping this process or even exploiting it to improve their own infectivity [33]. We previously reported that autophagy not only promotes PPRV replication in caprine endometrial epithelial cells (EECs) but also acts as a potential mechanism to inhibit PPRV-induced apoptosis [37]. The PPRV-H, PPRV-N and PPRV-C proteins significantly promote the autophagy pathway [37].…”

“…We previously reported that autophagy not only promotes PPRV replication in caprine endometrial epithelial cells (EECs) but also acts as a potential mechanism to inhibit PPRV-induced apoptosis [37]. The PPRV-H, PPRV-N and PPRV-C proteins significantly promote the autophagy pathway [37]. Furthermore, we previously showed that PPRV enters EECs via the caveolae-mediated endocytosis pathway [45].…”