The BZLF1 Homolog of an Epstein-Barr-Related γ-Herpesvirus Is a Frequent Target of the CTL Response in Persistently Infected Rhesus Macaques

Abstract

Although CD8+ T lymphocytes targeting lytic infection proteins dominate the immune response to acute and persistent EBV infection, their role in immune control of EBV replication is not known. Rhesus lymphocryptovirus (rhLCV) is a γ-herpesvirus closely related to EBV, which establishes persistent infection in rhesus macaques. In this study, we investigated cellular immune responses to the rhLCV BZLF1 (rhBZLF1) homolog in a cohort of rhLCV-seropositive rhesus macaques. rhBZLF1-specific IFN-γ ELISPOT responses ranging between 56 and 3070 spot-forming cells/106 PBMC were detected in 36 of 57 (63%) rhesus macaques and were largely mediated by CD8+ T lymphocytes. The prevalence and magnitude of ELISPOT responses were greater in adult (5–15 years of age) rather than juvenile macaques (<5 years of age), suggesting that rhBZLF1-specific CTL increase over time following early primary infection. A highly immunogenic region in the carboxyl terminus of the rhBZLF1 protein containing overlapping CTL epitopes restricted by Mamu-A*01 and other as yet unidentified MHC class I alleles was identified. The presence of a robust CD8+ T lymphocyte response targeting this lytic infection protein in both rhesus macaques and humans suggests that these CTL may be important for immune control of EBV-related γ-herpesvirus infection. These data underscore the utility of the rhLCV-macaque model for studies of EBV pathogenesis.

Measuring T-cell responses against LCV and CMV in cynomolgus macaques using ELISPOT: Potential application to non-clinical testing of immunomodulatory therapeutics

“…Using the IFN-g ELISPOT, CMV-reactive T-cells were detected at approximate frequencies in the range of &500-3000 SFC/10 6 PBMC (1/2000 to 1/300, respectively), and LCV-reactive T-cell frequencies in the range of &50-500 SFC/10 6 PBMC (1/20 000 to 1/2000, respectively). The frequencies we detect are similar to those reported in rhesus macaques for CMV (Ambagala et al, 2011;Kaur et al, 2002;Pitcher et al, 2002) and LCV (Fogg et al, 2005(Fogg et al, , 2006, as well as those reported in humans for CMV and EBV (Hislop et al, 2007;Tan et al, 1999;Waldrop et al, 1997), indicating that cynomolgus macaques are similar to rhesus macaques and humans with regards to the size of the memory T-cell pool specific for CMV and LCV.…”

IRF7 activation by Epstein–Barr virus latent membrane protein 1 requires localization at activation sites and TRAF6, but not TRAF2 or TRAF3

“…Indeed, the potentially oncogenic EBNA2, EB-NALP, EBNA3, EBNA3C, and LMP1 latency III transformation program may have not evolved without LMP1 induction of IFNmediated innate and adoptive immune responses (24). This latter hypothesis can be tested by infection of Rhesus macaques with Rhesus EBV, which has been reverse-genetically modified so as to express a dominant-negative inhibitor of LMP1 mediated IRF7 activation (52,53).…”

Animal models of Epstein Barr virus infection

“…Nevertheless, cell-mediated and humoral immune responses against rhLCV have been reported in macaques; however, their protective value remains unexplored in this in vivo system (Fogg et al, 2005;Fogg et al, 2006;Orlova et al, 2011a;Orlova et al, 2011b). The difficulty in manipulating the macaque immune system to interrogate the functional relevance of rhLCVspecific immune responses points to the limitation of this in vivo system.…”