Design and Analysis of Rhesus Cytomegalovirus IL-10 Mutants as a Model for Novel Vaccines against Human Cytomegalovirus

Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America.
PLoS ONE (Impact Factor: 3.23). 11/2011; 6(11):e28127. DOI: 10.1371/journal.pone.0028127
Source: PubMed


Human cytomegalovirus (HCMV) expresses a viral ortholog (CMVIL-10) of human cellular interleukin-10 (cIL-10). Despite only ∼26% amino acid sequence identity, CMVIL-10 exhibits comparable immunosuppressive activity with cIL-10, attenuates HCMV antiviral immune responses, and contributes to lifelong persistence within infected hosts. The low sequence identity between CMVIL-10 and cIL-10 suggests vaccination with CMVIL-10 may generate antibodies that specifically neutralize CMVIL-10 biological activity, but not the cellular cytokine, cIL-10. However, immunization with functional CMVIL-10 might be detrimental to the host because of its immunosuppressive properties.
Structural biology was used to engineer biologically inactive mutants of CMVIL-10 that would, upon vaccination, elicit a potent immune response to the wild-type viral cytokine. To test the designed proteins, the mutations were incorporated into the rhesus cytomegalovirus (RhCMV) ortholog of CMVIL-10 (RhCMVIL-10) and used to vaccinate RhCMV-infected rhesus macaques. Immunization with the inactive RhCMVIL-10 mutants stimulated antibodies against wild-type RhCMVIL-10 that neutralized its biological activity, but did not cross-react with rhesus cellular IL-10.
This study demonstrates an immunization strategy to neutralize RhCMVIL-10 biological activity using non-functional RhCMVIL-10 antigens. The results provide the methodology for targeting CMVIL-10 in vaccine, and therapeutic strategies, to nullify HCMV's ability to (1) skew innate and adaptive immunity, (2) disseminate from the site of primary mucosal infection, and (3) establish a lifelong persistent infection.

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Available from: Christopher Allen, Jun 20, 2014
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    • "An alternative approach to develop a vaccine whereby mutated versions of viral IL-10 unable to bind to the IL-10R but still able to stimulate production of anti-viral IL-10-neutralizing antibodies has also been investigated. Immunization of seronegative animals with mutated forms of viral IL-10 prior to challenge with RhCMV resulted in decreased viral replication both locally (at the site of RhCMV infection) and systemically (with reduced viral shedding in bodily fluids; Logsdon et al., 2011; Eberhardt et al., 2013). "
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    ABSTRACT: Human cytomegalovirus (HCMV), a clinically important β-herpesvirus, is a master of evasion and modulation of the host immune system, including inhibition of a number of dendritic cell (DC) functions. DCs play a central role in co-ordination of the immune response against pathogens and any disturbance of DCs functions can result in a cascade effect on a range of immune cells. Recently, the HCMV gene UL111A, which encodes viral homologs of human interleukin 10, has been identified as a strong suppressor of a number of DCs functions. In this mini review, we focus on HCMV-encoded viral IL-10-mediated inhibitory effects on DCs and implications for the development of an effective HCMV vaccine.
    Frontiers in Microbiology 07/2014; 5. DOI:10.3389/fmicb.2014.00337 · 3.99 Impact Factor
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    • "This theoretical possibility could apply to most vIL-10s that are quite divergent in sequence from the host IL-10. To address this concept using the RhCMV model (Yue & Barry, 2008), inactive RhCMV vIL-10 mutants were designed as antigen candidates and shown to induce the production of neutralizing antibodies specific to vIL-10 (not cross-reacting with host IL-10) (de Lemos Rieper et al., 2011; Logsdon et al., 2011). The ability of such an antigen candidate to interfere with persistent RhCMV infection (establishment or maintenance) has not yet been tested. "
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    ABSTRACT: Many viruses have evolved strategies to deregulate the host immune system. These strategies include mechanisms to subvert or recruit the host cytokine network. Interleukin-10 (IL-10) is a pleiotropic cytokine that has both immunostimulatory and immunosuppressive properties. However, its key features relate mainly to its capacity to exert potent immunosuppressive effects. Several viruses have been shown to up regulate the expression of cellular IL 10 (cIL-10), with, in some cases, enhancement of infection by suppression of immune functions. Other viruses encode functional orthologues of cIL-10, called viral IL-10s (vIL-10s). The present review is devoted to these virokines. To date, vIL-10 orthologues have been reported for 12 members of the family Herpesviridae, two members of the family Alloherpesviridae, and seven members of the family Poxviridae. Study of vIL-10s demonstrated several interesting aspects on the origin and the evolution of these viral genes; such as for example, the existence of multiple (potentially up to 9) independent gene acquisition events at different times during evolution, viral gene acquisition resulting from recombination with cellular genomic DNA or cDNA derived from cellular mRNA, and the evolution of cellular sequence in the viral genome to restrict the biological activities of the viral orthologues to those beneficial for the virus life cycle. In this review, various aspects of the vIL 10s described to date are reviewed, including their genetic organization, protein structure, origin, evolution, biological properties and potential in applied research.
    Journal of General Virology 11/2013; 95(Pt_2). DOI:10.1099/vir.0.058966-0 · 3.18 Impact Factor
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    • "Thus, there is extensive precedent to focus on rhcmvIL-10 and cmvIL-10 as central players in primate CMV natural history. The potential viability of using rhcmvIL-10 in a vaccine was recently described for rhcmvIL-10 [40]. Structural biology was used to engineer biologically inactive mutants of rhcmvIL-10 that do not bind to the IL-10 high-affinity receptor and, therefore, lack wild-type functional activity. "
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    ABSTRACT: Considerable evidence has accumulated that multiple viruses, bacteria, and protozoa manipulate interleukin-10 (IL-10)-mediated signaling through the IL-10 receptor (IL-10R) in ways that could enable establishment of a persistent microbial infection. This suggests that inhibition of pathogen targeting of IL-10/IL-10R signaling could prevent microbial persistence. Human cytomegalovirus (HCMV) and rhesus cytomegalovirus (RhCMV) express a viral interleukin-10 (cmvIL-10 and rhcmvIL-10, respectively) with comparable immune modulating properties in vitro to that of their host's cellular IL-10 (cIL-10). A prior study noted that rhcmvIL-10 alters innate and adaptive immunity to RhCMV in vivo, consistent with a central role for rhcmvIL-10 during acute virus-host interactions. Since cmvIL-10 and rhcmvIL-10 are extremely divergent from the cIL-10 of their respective hosts, vaccine-mediated neutralization of their function could inhibit establishment of viral persistence without inhibition of cIL-10. As a prelude to evaluating cmvIL-10-based vaccines in humans, the rhesus macaque model of HCMV was used to interrogate peripheral and mucosal immune responses to rhcmvIL-10 in RhCMV-infected animals. ELISA were used to detect rhcmvIL-10-binding antibodies in plasma and saliva, and an IL-12-based bioassay was used to quantify plasma antibodies that neutralized rhcmvIL-10 function. rhcmvIL-10 is highly immunogenic during RhCMV infection, stimulating high avidity rhcmvIL-10-binding antibodies in the plasma of all infected animals. Most infected animals also exhibited plasma antibodies that partially neutralized rhcmvIL-10 function but did not cross-neutralize the function of rhesus cIL-10. Notably, minimally detectable rhcmvIL-10-binding antibodies were detected in saliva. This study demonstrates that rhcmvIL-10, as a surrogate for cmvIL-10, is a viable vaccine candidate because (1) it is highly immunogenic during natural RhCMV infection, and (2) neutralizing antibodies to rhcmvIL-10 do not cross-react with rhesus cIL-10. Exceedingly low rhcmvIL-10 antibodies in saliva further suggest that the oral mucosa, which is critical in RhCMV natural history, is associated with suboptimal anti-rhcmvIL-10 antibody responses.
    PLoS ONE 05/2012; 7(5):e37931. DOI:10.1371/journal.pone.0037931 · 3.23 Impact Factor
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