Human parainfluenza virus type 3 upregulates ICAM-1 (CD54) expression in a cytokine-independent manner.

Human parainfluenza virus type 3 (HPIV3) causes bronchiolitis, pneumonia, and croup in newborns and infants. Several studies have implicated intercellular adhesion molecule-1 (ICAM-1) in inflammation during infection by viruses. In this study, we investigated the potential for HPIV3 to induce ICAM-1 in HT1080 cells. FACS analysis showed that HPIV3 strongly induced ICAM-1 expression in these cells. The ICAM-1 induction was significantly reduced when the virions were UV inactivated prior to infection, indicating that ICAM-1 induction was mostly viral replication dependent. Culture supernatant of HPIV3-infected cells induced ICAM-1 at an extremely low level, indicating that virus-induced cytokines played only a minor role in the induction process. Consistent with this, potent inducers of ICAM-1 such as IFN-gamma, TGF-beta, and TNF-alpha were absent in the culture supernatant, but a significant amount of IFN type 1 was present. By using U2A cells, which are defective in IFN type I signaling, we confirmed that ICAM-1 induction by HPIV3 occurred in a JAK/STAT signaling-independent manner. These data strongly indicate that HPIV3 induces ICAM-1 directly by viral antigens in a cytokine-independent manner; this induction may play a role in the inflammation during HPIV3 infection.