Attenuation of the Adaptive Immune Response in Rhesus Macaques Infected with Simian Varicella Virus Lacking Open Reading Frame 61

Abstract

dVaricella zoster virus (VZV) is a neurotropic alphaherpesvirus that causes chickenpox during primary infection and establishes latency in sensory ganglia. Infection of rhesus macaques (RM) with the homologous simian varicella virus (SVV) recapitulates hallmarks of VZV infection. We have shown that an antisense transcript of SVV open reading frame 61 (ORF61), a viral transactivator, was detected most frequently in latently infected RM sensory ganglia. In this study, we compared disease progression, viral replication, immune response, and the establishment of latency following intrabronchial infection with a recombinant SVV lacking ORF61 (SVV⌬ORF61) to those following infection with wild-type (WT) SVV. Varicella severity and viral latency within sensory ganglia were comparable in RMs infected with SVV⌬ORF61 and WT SVV. In contrast, viral loads, B and T cell responses, and plasma inflammatory cytokine levels were decreased in RMs infected with SVV⌬ORF61. To investigate the mechanisms underlying the reduced adaptive immune response, we compared acute SVV gene expression, frequency and proliferation of dendritic cell (DC) subsets, and the expression of innate antiviral genes in bronchoalveolar lavage (BAL) samples. The abundance of SVV transcripts in all kinetic classes was significantly decreased in RMs infected with SVV⌬ORF61. In addition, we detected a higher frequency and proliferation of plasmacytoid dendritic cells in BAL fluid at 3 days postinfection in RMs infected with SVV⌬ORF61, which was accompanied by a slight increase in type I interferon gene expression. Taken together, our data suggest that ORF61 plays an important role in orchestrating viral gene expression in vivo and interferes with the host antiviral interferon response. V aricella zoster virus (VZV) is a neurotropic human alphaherpesvirus that causes chickenpox (varicella) during primary infection. VZV establishes a life-long latent infection in sensory ganglia, including the trigeminal and dorsal root ganglia. Reactivation of VZV leads to herpes zoster (HZ; shingles), which is estimated to affect 1 million individuals each year in the United States and can result in significant morbidity and occasionally mortality in aged and immunocompromised individuals (1-4). Reactivation of VZV is generally believed to be due to a decline in T cell immunity (5-10); however, the viral genes that control the switch between latent and lytic replication remain unknown. This is due in part to the fact that VZV is strictly a human pathogen, and animal models of VZV infection recapitulate only certain aspects of pathogenesis. We have previously shown that rhesus macaques (RMs) infected with simian varicella virus (SVV) display the hallmarks of VZV infection in humans, including generalized varicella, development of cellular and humoral immunity, and establishment of latency (11).Utilizing this model, we previously found that SVV open reading frame 61 (ORF61) was the most prevalent transcript detected during latency in sensory ganglia (12). Interestingly, SVV ORF61 ...

Robust pro-inflammatory and lesser anti-inflammatory immune responses during primary simian varicella virus infection and reactivation in rhesus macaques

“…High levels of pro-inflammatory mediators IFN-γ, IL-6, MCP-1, IP-10 and I-TAC and anti-inflammatory cytokine IL-1Ra were seen at 4–14 dpi in all five monkeys. Our results confirm and extend a recent report of increased levels of IL-6, IFN-γ and IL-1Ra during primary SVV infection in rhesus macaques (Meyer et al 2013), findings consistent with a strong pulmonary innate immune response to SVV after respiratory exposure. IFN-γ is produced by lymphocytes during primary varicella zoster virus infection (Arvin et al 1986) and suppresses VZV replication in vitro (Rabalais et al 1989).…”

The ORF61 Protein Encoded by Simian Varicella Virus and Varicella-Zoster Virus Inhibits NF-κB Signaling by Interfering with IκBα Degradation

“…Thus, ORF61 might be responsible for eliminating residual phosphorylated IB␣ that escaped the upstream inhibitory mechanism. Deletion of ORF61 alone thus does not restore NF-B-mediated innate immunity, which might explain why SVV lacking ORF61 was still able to establish primary and latent infection in rhesus macaques, as reported by Meyer et al (81). However, SVV with ORF61 deleted displayed reduced viral gene expression in vivo, which could either be related to the transactivator function of ORF61 or due to increased expression of antiviral genes that suppress viral gene expression.…”

“…However, SVV with ORF61 deleted displayed reduced viral gene expression in vivo, which could either be related to the transactivator function of ORF61 or due to increased expression of antiviral genes that suppress viral gene expression. In addition, there was an increased frequency of plasmacytoid dendritic cells in the bronchoalveolar lavage (BAL) fluid and an increase in IFN-␤ gene expression in SVV⌬ORF61-infected animals (81). Enhanced recruitment of dendritic cells and enhanced cytokine expression could be the direct result of increased NF-B activity by infected cells due to lack of ORF61 inhibition, or lack of ORF61 could indirectly affect innate immune responses by reduced transactivation of other viral genes that interfere with innate signaling pathways, such as IE62 (80) and ORF63 (82,83).…”

Impact of irradiation and immunosuppressive agents on immune system homeostasis in rhesus macaques

“…JAK inhibitor (tofacitinib citrate, CP-690550 citrate; Selleckchem, Houston, TX, USA) at 15 mg/kg diluted in 0Á5% methylcellulose was given for 5 consecutive days by oral gavage [29]. Each cohort consisted of four animals, which is the minimum number of animals needed to achieve sufficient power to detect a statistically significant difference in various immunological parameters following SVV infection [37,[56][57][58][59]. The necropsy schedules were based on the return of white blood cell (WBC) counts to baseline levels and the cessation of lymphocyte proliferation.…”