Syndecan-4, a PRRSV attachment factor, mediates PRRSV entry through its interaction with EGFR

• Syndecan-4 is a PRRSV attachment factor in MACR-145 cells.
• EGFR interacts with syndecan-4 in MACR-145 cells.
• SDC4-EGFR interaction is important for PRRSV entry in MARC-145 cells.

The causative agent of porcine reproductive and respiratory syndrome is the PRRS virus (PRRSV), an enveloped, single-stranded and positive-sense RNA virus. The host factors and mechanisms that are involved in PRRSV entry are still largely unknown. In our present studies, we found that syndecan-4, one of the heparan sulfate proteoglycans, plays a critical role in PRRSV entry, especially in PRRSV attachment. Moreover, EGFR interacts with syndecan-4 in MACR-145 cells and disruption of their interaction impaired PRRSV entry. Furthermore, EGFR inhibitor AG1478 or syndecan-4 derived peptide SSTN87-131 inhibited syndecan-4 endocytosis induced by PRRSV entry. Altogether, syndecan-4, a PRRSV attachment factor, mediated PRRSV entry by interacting with EGFR.