RSV is a major cause of severe lower respiratory infection in infants and young children. With no vaccine yet available, it is important to clarify mechanisms of disease pathogenesis. Since indoleamine-2,3-dioxygenase (IDO) is an immunomodulatory enzyme and is upregulated with RSV infection, we studied it in vivo during infection of BALB/c mice and in vitro in A549 cells. RSV infection upregulated IDO transcripts in vivo and in vitro. IDO siRNA decreased IDO transcripts ~2 fold compared to control siRNA after RSV infection but this decrease did not affect RSV replication. In the presence of IFN-γ, siRNA-induced a decrease in IDO expression that was associated with an increase in virus replication and increased levels of IL-6, IL-8, CXCL10 and CCL4. Thus, our results show IDO is upregulated with RSV infection and this upregulation likely participates with IFN-γ in inhibition of virus replication and suppression of some host cell responses to infection.

RSV是婴幼儿严重下呼吸道感染的主要原因。由于尚无可用的疫苗，弄清疾病的发病机理很重要。由于吲哚胺-2,3-双加氧酶（IDO）是免疫调节酶和被上调与RSV感染，我们研究了其在体内的BALB / c小鼠的感染过程中和在体外在A549细胞中。RSV感染在体内和体外上调了IDO转录本。与RSV感染后的对照siRNA相比，IDO siRNA降低了IDO转录本约2倍，但这种降低并不影响RSV复制。在存在IFN-γ的情况下，siRNA导致IDO表达下降，这与病毒复制的增加以及IL-6，IL-8，CXCL10和CCL4的水平升高有关。因此，我们的结果表明IDO受到RSV感染的上调，而这种上调可能与IFN-γ一起参与了病毒复制的抑制和某些宿主细胞对感染的反应的抑制。