The porcine reproductive and respiratory syndrome virus requires trafficking through CD163-positive early endosomes, but not late endosomes, for productive infection.

The porcine reproductive and respiratory syndrome virus (PRRSV) enters its target cell via clathrin-mediated endocytosis. Using dominant-negative Rab5 and Rab7 mutants, we show that upon internalization, PRRSV enters early endosomes but does not continue through the endocytic pathway to late endosomes. This was confirmed via colocalization experiments visualizing PRRSV and markers for different compartments of the endocytic pathway. Furthermore, it was shown that PRRSV colocalizes with its internalization receptor, sialoadhesin, on the cell surface and beneath the plasma membrane, while CD163 and PRRSV only meet in early endosomes.