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Abstract
Type I interferons (IFN) are potent inducers of an anti-viral state in response to infection and have been demonstrated to inhibit cytomegalovirus (CMV) replication both in vitro and in vivo. CMV, like all herpes viruses, has the capacity to establish lifelong infections of host through the establishment of latency. As the very early stages of viral entry can trigger IFN responses we investigated the impact of IFN on the establishment of latent human CMV (HCMV) in myeloid progenitor cells. Here we show that priming of myeloid THP1 cells with type I IFN prior to infection skews infection towards a more efficient establishment of latency. This is evidenced by detection of reduced lytic gene expression, increased latent gene expression, and increased levels of reactivation following differentiation. Blockade of IFN signalling with neutralising antibodies antagonised the latent phenotype suggesting that endogenous IFN production upon infection contributed to the effect observed. Intriguingly, whilst both IFNα2 and IFNβ can drive latent infection individually, their effects were dose-dependent and demonstrated a biphasic impact on the establishment of latency, with the highest doses of IFN preventing both lytic and latent infection. These data demonstrate that the HCMV derives an unexpected benefit from IFN production. They support a hypothesis that, although anti-viral in nature, concentration-specific effects of IFN may be evident in the cells which can modulate different outcomes post infection in persistent viruses such as HCMV. Future work is identifying the IFN concentration-specific effects responsible for a cellular environment that favours the establishment of latency.
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