Coronavirus Porcine Epidemic Diarrhea Virus Utilizes Chemokine Interleukin-8 to Facilitate Viral Replication by Regulating Ca2+ Flux

Chemokine production by epithelial cells is crucial for neutrophil recruitment to sites of inflammation during viral Infection. However, the effect of chemokine on epithelia and how chemokine is involved in coronavirus Infection remains to be fully understood. Here, we identified an inducible chemokine interleukin-8 (CXCL8/IL-8), which could promote coronavirus porcine epidemic diarrhea virus (PEDV) Infection in African green monkey kidney epithelial cells (Vero) and Lilly Laboratories cell-porcine kidney 1 epithelial cells (LLC-PK1). IL-8 deletion restrained cytosolic calcium (CA²⁺), whereas IL-8 stimulation improved cytosolic CA²⁺. The consumption of CA²⁺ restricted PEDV Infection. PEDV internalization and budding were obvious reductions when cytosolic CA²⁺ was abolished in the presence of CA²⁺ Chelators. Further study revealed that the upregulated cytosolic CA²⁺ redistributes intracellular CA²⁺. Finally, we identified that G protein-coupled receptor (GPCR)-phospholipase C (PLC)-inositol trisphosphate receptor (IP3R)-store-operated CA²⁺ (SOC) signaling was crucial for enhancive cytosolic CA²⁺ and PEDV Infection. To our knowledge, this study is the first to uncover the function of chemokine IL-8 during coronavirus PEDV Infection in epithelia. PEDV induces IL-8 expression to elevate cytosolic CA²⁺, promoting its Infection. Our findings reveal a novel role of IL-8 in PEDV Infection and suggest that targeting IL-8 could be a new approach to controlling PEDV Infection. IMPORTANCE Coronavirus porcine epidemic diarrhea virus (PEDV) is a highly contagious enteric coronavirus that caused severe economic losses worldwide, and more effort is needed to develop economical and efficient vaccines to control or eliminate this disease. The chemokine interleukin-8 (CXCL8/IL-8) is indispensable for the activation and trafficking of inflammatory mediators and tumor progression and metastasis. This study evaluated the effect of IL-8 on PEDV Infection in epithelia. We found that IL-8 expression improved cytosolic CA²⁺ in epithelia, facilitating PEDV rapid internalization and egress. G protein-coupled receptor (GPCR)-phospholipase C (PLC)-inositol trisphosphate receptor (IP3R)-SOC signaling was activated by IL-8, releasing the intracellular CA²⁺ stores from endoplasmic reticulum (ER). These findings provide a better understanding of the role of IL-8 in PEDV-induced immune responses, which will help develop small-molecule drugs for coronavirus cure.

calcium signaling; infection; interleukin-8; porcine epidemic diarrhea virus; therapy.