Lymphatic Type 1 Interferon Responses Are Critical for Control of Systemic Reovirus Dissemination

Abstract

Mammalian orthoreovirus (reovirus) spreads from the site of infection to every organ system in the body via the blood. However, mechanisms that underlie reovirus hematogenous spread remain undefined. Non-structural protein σ1s is a critical determinant of reovirus bloodstream dissemination that is required for efficient viral replication in many types of cultured cells. Here, we used the specificity of the σ1s protein for promoting hematogenous spread as a platform to uncover a role for lymphatic type-1 interferon (IFN-1) responses in limiting reovirus systemic dissemination. We found that replication of a σ1s-deficient reovirus was restored to wild-type levels in cells with defective type-1 interferon α-receptor (IFNAR1) signaling. Reovirus spreads systemically following oral inoculation of neonatal mice, whereas the σ1s-null virus remains localized to the intestine. We found that σ1s enables reovirus spread in the presence of a functional IFN-1 response, as the σ1s-deficient reovirus disseminated comparably to wild-type virus in IFNAR1-/- mice. Lymphatics are hypothesized to mediate reovirus spread from the intestine to the bloodstream. IFNAR1 deletion from cells expressing lymphatic vessel endothelium receptor-1 (LYVE-1), a marker for lymphatic endothelial cells, enabled the σ1s-deficient reovirus to disseminate systemically. Together, our findings indicate that IFN-1 responses in lymphatics limit reovirus dissemination. Our data further suggest that the lymphatics are an important conduit for reovirus hematogenous spread. IMPORTANCE Type-1 interferons (IFN-1) are critical host responses to viral infection. However, the contribution of IFN-1 responses to control of viruses in specific cell and tissue types is not fully defined. Here, we identify IFN-1 responses in lymphatics as important for limiting reovirus dissemination. We found that nonstructural protein σ1s enhances reovirus resistance to IFN-1 responses, as a reovirus mutant lacking σ1s was more sensitive to IFN-1 than wild-type virus. In neonatal mice, σ1s is required for reovirus systemic spread. We used tissue-specific IFNAR1 deletion in combination with the IFN-1-sensitive σ1s-null reovirus as a tool to test how IFN-1 responses in lymphatics affect reovirus systemic spread. Deletion of the type-1 interferon α-receptor (IFNAR1) in lymphatic cells using Cre-lox technology enabled dissemination of the IFN-1-sensitive σ1s-deficient reovirus. Together, our results indicate that IFN-1 responses in lymphatics are critical for controlling reovirus systemic spread.

Infection-induced lymphatic zippering restricts fluid transport and viral dissemination from skin

“…Similar mechanisms have been proposed in encephalitic flavivirus infection, where IFN-λ reduces blood-brain barrier permeability and viral transport (Lazear et al, 2015). These data also add to recent findings that viruses may specifically subvert the lymphatic vasculature to disseminate via lymph (Phillips et al, 2021), together indicating that the lymphatic vasculature is a critical innate barrier to viral dissemination from peripheral tissue.…”

The M2 Gene Is a Determinant of Reovirus-Induced Myocarditis

“…We also assessed virulence following intracranial (IC) inoculation. Similar to oral inoculation, T1 reoviruses also disseminate systemically following IC inoculation (28,29). Like we observed following oral inoculation, T1L/T3DM2 produced higher viral titers at earlier time points and had higher peak viral loads compared to T1L in each organ when virus was introduced IC ( .…”

Infection-Induced Dermal Lymphatic Zippering Restricts Viral Dissemination from Skin and Promotes Anti-Viral CD8+ T Cell Expansion

“…We previously also demonstrated that host type I IFN sensing was required for reduced fluid transport and viral sequestration following VACV scarification (Loo et al, 2017), however, whether type I IFNs act through lymphatic-specific changes in junctional morphology remains to be explored. These data add to recent findings that viruses may also specifically acquire mechanisms to subvert the lymphatic vasculature to mediate dissemination from the site of infection (Phillips et al, 2020). The nonstructural protein s1s expressed by orthoreovirus suppresses type I IFN responses in LECs and may result in direct release of viable virions into lymph driving dissemination.…”

“…The nonstructural protein s1s expressed by orthoreovirus suppresses type I IFN responses in LECs and may result in direct release of viable virions into lymph driving dissemination. In the absence of s1s, LEC-derived type I IFN responses limit orthoreovirus dissemination from the intestine (Phillips et al, 2020). Together this work indicates that the lymphatic vasculature is a critical barrier to viral dissemination from peripheral non-lymphoid tissue.…”