Wills, M. | Search bioRxiv

bioRxiv2020

Targeting the latent human cytomegalovirus reservoir with virus specific nanobodies

Latent reservoirs of viral pathogens are significant barriers to eradication of these viruses. During latency, herpesviruses maintain their genome, with little gene expression, making latent infections refractory to current treatments targeting viral replication. In the case of human cytomegalovirus (HCMV), sporadic reactivation events are well controlled by the immune system. However, in immunocompromised or immunosuppressed individuals, HCMV reactivation often results in morbidity in solid organ and stem cell transplant patients. Clearance of the latent reservoir could lower the incidence and severity of HCMV-associated disease. Here, we develop a virus specific nanobody (VUN100b) that partially inhibits signaling of the viral receptor US28. VUN100b treatment partially reverses latency without fully reactivating the virus. Moreover, VUN100b treatment drives recognition and killing of latently infected monocytes by autologous cytotoxic T lymphocytes from HCMV-seropositive individuals. This study shows the potential of VUN100b as a therapy to clear the HCMV latent reservoir of transplant patients.

microbiology↗

bioRxiv2019

Interferon-responsive genes are targeted during the establishment of human cytomegalovirus latency

Human cytomegalovirus (HCMV) latency is an active process which remodels the latently infected cell to optimise latent carriage and reactivation. This is achieved, in part, through the expression of viral genes, including the G-protein coupled receptor US28. Here, we use an unbiased proteomic screen to assess changes in host proteins induced by US28, revealing that interferon-inducible genes are downregulated by US28. We validate that MHC Class II and two PYHIN proteins, MNDA and IFI16, are downregulated during experimental latency in primary human CD14+ monocytes. We find that IFI16 is targeted rapidly during the establishment of latency in a US28-dependent manner, but only in undifferentiated myeloid cells, a natural site of latent carriage. Finally, by overexpressing IFI16, we show that IFI16 can activate the viral major immediate early promoter and immediate early gene expression during latency via NF-{kappa}B, a function which explains why downregulation of IFI16 during latency is advantageous for the virus.\n\nImportanceHuman cytomegalovirus (HCMV) is a ubiquitous herpesvirus which infects 50-100% of humans worldwide. HCMV causes a lifelong subclinical infection in immunocompetent individuals, but is a serious cause of mortality and morbidity in the immunocompromised and in neonates. In particular, reactivation of HCMV in the transplant setting is a major cause of transplant failure and related disease. Therefore, a molecular understanding of HCMV latency and reactivation could provide insights into potential ways to target the latent viral reservoir in at-risk patient populations.

microbiology↗