Recombinant Murine Gamma Herpesvirus 68 Carrying KSHV G Protein-Coupled Receptor Induces Angiogenic Lesions in Mice

Abstract

Human gamma herpesviruses, including Kaposi’s sarcoma-associated herpesvirus (KSHV) and Epstein-Barr virus (EBV), are capable of inducing tumors, particularly in in immune-compromised individuals. Due to the stringent host tropism, rodents are resistant to infection by human gamma herpesviruses, creating a significant barrier for the in vivo study of viral genes that contribute to tumorigenesis. The closely-related murine gamma herpesvirus 68 (γHV68) efficiently infects laboratory mouse strains and establishes robust persistent infection without causing apparent disease. Here, we report that a recombinant γHV68 carrying the KSHV G protein-coupled receptor (kGPCR) in place of its murine counterpart induces angiogenic tumors in infected mice. Although viral GPCRs are conserved in all gamma herpesviruses, kGPCR potently activated downstream signaling and induced tumor formation in nude mouse, whereas γHV68 GPCR failed to do so. Recombinant γHV68 carrying kGPCR demonstrated more robust lytic replication ex vivo than wild-type γHV68, although both viruses underwent similar acute and latent infection in vivo. Infection of immunosuppressed mice with γHV68 carrying kGPCR, but not wild-type γHV68, induced tumors in mice that exhibited angiogenic and inflammatory features shared with human Kaposi’s sarcoma. Immunohistochemistry staining identified abundant latently-infected cells and a small number of cells supporting lytic replication in tumor tissue. Thus, mouse infection with a recombinant γHV68 carrying kGPCR provides a useful small animal model for tumorigenesis induced by a human gamma herpesvirus gene in the setting of a natural course of infection.

Species-Specific Deamidation of cGAS by Herpes Simplex Virus UL37 Protein Facilitates Viral Replication

“…Murine gamma herpesvirus 68 (MHV68) viruses were propagated in BHK21 cells (Zhang et al, 2015b). Herpes simplex virus 1 (HSV-1) WT and UL37C819S recombinant viruses were propagated using Vero cells.…”

Extracellular vesicles: novel vehicles in herpesvirus infection

“…There are few available models for KSHV, but in a mouse model of KSHV and in patients with KSHVassociated malignancies, exosomal miRNAs of the host and those encoded by KSHV, including the miR-17-92 cluster, were successfully detected. Furthermore, the characterization and analysis of exosomal miRNAs, their targets, and endothelial cells revealed that exosomes containing a wide variety of miRNAs play a functional biological role in signaling pathways linked to the pathogenesis of KSHV and its phenotypic characteristics (Chugh et al, 2013;Zhang et al, 2015a). Hence, distinct exosomal miRNAs are expected to represent a portion of the paracrine signaling mechanism, which is the hallmark of KSHV tumorigenesis.…”

Hijacking GPCRs by viral pathogens and tumor

“…An elegant study employed an endothelial cell specific retroviral delivery system to demonstrate that the expression of vGPCR, among multiple suspected KSHV oncogenes, was sufficient to induce KS-like tumors in mice [29]. Murine gamma herpesvirus 68 (γHV68) carrying KSHV vGPCR, rather than murine γHV68 GPCR (mGPCR), induced angiogenic lesions in virus-infected mice, offering a murine model of viral oncogenesis in the context of true viral infection [30]. Together, these studies support that KSHV vGPCR may significantly contribute to the sarcomagenesis of KSHV-infected patients.…”

“…It is only expressed in a small subset of cells (∼5%) in human KS or KS-like lesions in model animals [25, 29, 30, 33]. To reconcile this paradox, it is postulated that dysregulated abortive lytic replication may permit the expression of a subset of lytic genes, including vGPCR, to avoid late gene expression and lysis of host cells.…”

“…In contrast to its KSHV homologue, γHV68 mGPCR doesn't have constitutive activity [30, 42] and it has an HRC motif rather than the conventional DRY motif. Interestingly, KSHV vGPCR has a VRY motif, rather than a DRY motif and the V142D revertant mutation didn't alter the constitutive activity of vGPCR [43].…”