Novel and potent antiviral strategies against porcine coronaviruses infection

Coronavirus infection has threatened human and animal health for a long time.
Despite multiple efforts, porcine coronavirus has caused large financial losses in the
global swine industry. Thus, identifying novel and potent strategies to combat porcine
coronaviruses and elucidating the underlying mechanisms are urgently needed. We
aim to develop two strategies to control coronaviruses infection. The first strategy
focuses on discovering a method to control viral cell receptors, thereby closing the
door to viral entry and combating viral infections. The second strategy is to elucidate
the mechanism of inflammatory responses induced by porcine coronavirus,
identifying critical host factors involved, and thereby developing methods to
effectively control the viral infection.
1. Potassium molybdate blocks APN-dependent coronavirus entry by
degrading receptor via PIK3C3-mediated autophagy
Aminopeptidase N (APN) is one of the most important receptors of coronavirus.
Modulating APN expression can represent a novel approach for controlling APNdependent coronaviruses and their variants infection. Here, we found that a chemical
compound potassium molybdate (PM) negatively regulates APN expression by
inducing PIK3C3-mediated autophagy against APN-dependent coronavirus
internalization, including transmissible gastroenteritis virus (TGEV) and porcine
respiratory coronavirus (PRCV). Furthermore, PM can promote PIK3C3-BECN1-
ATG14 complex assembly to induce autophagic degradation of APN by upregulating
PIK3C3 Ser249 phosphorylation. Lastly, pig experiments also confirmed that PM can
trigger PIK3C3-mediated autophagic degradation of APN to restrict TGEV
pathogenicity in vivo without toxicity. Our findings underscore the promising
potential of PM as an effective agent against APN-dependent coronavirus and
potentially emerging viral diseases entry.
2. Inhibition of HIF-1α restricts TGEV replication and mitigates virus-induced
inflammation.
In the second part of research explores the mechanism of inflammatory responses
induced by porcine coronaviruses. We developed intestinal organoids to investigate
immune responses to virus infection, which can better represent the physiological
environment compared with well-established cell lines. In addition, the results
demonstrated that inflammatory responses induced by TGEV infection were regulated
by the RIG-I/NF-κB/HIF-1α/glycolysis axis in apical-out porcine organoids and in
pigs. Our findings contribute to understanding the mechanism of intestinal
inflammation upon viral infection and highlight apical-out organoids as a
physiological model to mimic virus-induced inflammation.
Apart from its role in inflammation, HIF-1α was shown to facilitate TGEV infection
by targeting viral replication, which was achieved by restraining type I and type III
interferon (IFN) production. In vivo experiments in piglets demonstrated that the HIF-
1α inhibitor BAY87-2243 (BAY87) significantly reduced HIF-1α expression and
inhibited TGEV replication and pathogenesis by activating IFN expression. In
summary, we unveiled that HIF-1α can be a novel antiviral target and BAY87 can be
a candidate drug against TGEV replication in vitro, ex vivo, and in vivo.6
In conclusion, this thesis provides two novel and potent antiviral strategies against
porcine coronaviruses infection. First of all, we unveil that PM can control cell
receptor APN expression to block APN-dependent coronavirus entry by PIK3C3-
mediated autophagy. In addition, inhibition of HIF-1α restricts TGEV replication and
mitigates virus-induced inflammation. These studies provide new directions for the
prevention and control of porcine coronaviruses.