Examining the Species-Specificity of Rhesus Macaque Cytomegalovirus (RhCMV) in Cynomolgus Macaques

Abstract

Cytomegalovirus (CMV) is a highly species-specific virus that has co-evolved with its host over millions of years and thus restricting cross-species infection. To examine the extent to which host restriction may prevent cross-species research between closely related non-human primates, we evaluated experimental infection of cynomolgus macaques with a recombinant rhesus macaque-derived CMV (RhCMV-eGFP). Twelve cynomolgus macaques were randomly allocated to three groups: one experimental group (RhCMV-eGFP) and two control groups (UV-inactivated RhCMV-eGFP or media alone). The animals were given two subcutaneous inoculations at week 0 and week 8, and a subset of animals received an intravenous inoculation at week 23. No overt clinical or haematological changes were observed and PBMCs isolated from RhCMV-eGFP inoculated animals had comparable eGFP- and IE-1-specific cellular responses to the control animals. Following inoculation with RhCMV-eGFP, we were unable to detect evidence of infection in any blood or tissue samples up to 4 years post-inoculation, using sensitive viral co-culture, qPCR, and Western blot assays. Co-culture of urine and saliva samples demonstrated the presence of endogenous cynomolgus CMV (CyCMV) cytopathic effect, however no concomitant eGFP expression was observed. The absence of detectable RhCMV-eGFP suggests that the CyCMV-seropositive cynomolgus macaques were not productively infected with RhCMV-eGFP under these inoculation conditions. In a continued effort to develop CMV as a viral vector for an HIV/SIV vaccine, these studies demonstrate that CMV is highly restricted to its host species and can be highly affected by laboratory cell culture. Consideration of the differences between lab-adapted and primary viruses with respect to species range and cell tropism should be a priority in evaluating CMV as vaccine vector for HIV or other pathogens at the preclinical development stage.

Cross-Species Rhesus Cytomegalovirus Infection of Cynomolgus Macaques

“…Since the induction of T cell responses is a highly sensitive indicator of viral infection, this result indicates that RhCMV 68–1 was unable to infect MCM (Fig 6B, top row). This result is consistent with previously published results, which showed lack of immune responses, viral shedding, and viral replication upon inoculation of MCM with RhCMV 68–1 [24]. …”

“…We show that RhCMV 68–1 and RhCMV 68–1.2 both replicate in cultured primary MCM fibroblasts, supporting previous reports of cross-species CMV infections in vitro [5]. However, we did not observe RhCMV 68–1 infection of MCM in vivo , supporting the previous findings of Marsh et al [24]. In contrast, RhCMV 68–1.2 established a productive infection as measured by generation of transgene-specific T cell immunity and shedding of virus in urine.…”

“…al . recently reported that RhCMV 68–1, the strain used to construct our vaccine vectors, is incapable of infecting Mauritian cynomolgus macaques (MCM), a population with simplified MHC genetics [20–24]. These results cast doubt on CM as a surrogate model for testing of RhCMV vaccine vectors.…”

Primary Tree Shrew Dermis Fibroblasts Support Lytic Replication of Human Cytomegalovirus

“…The species specificity of HCMV is the result of coevolution with human host that the interplay between the virus and the Chinese tree shrew would affect its cross-species infection. Although the mechanism of cross-species barrier of HCMV is still unknown, studies on other CMVs have implied that multiple factors play a part in this process [21][22][23][24][25][26]. On the viral side, UL128 and UL130 which are the subunit of pentameric complex in the viral envelope helped rhesus macaques CMV (RhCMV) infect cynomolgus macaques both in vitro and in vivo [26].…”

A critical analysis of the cynomolgus macaque, Macaca fascicularis, as a model to test HIV-1/SIV vaccine efficacy

“…However, CMV strains are extremely host restricted and unsuccessful attempts at infecting cynomolgus macaques with rhesus CMV [107] necessitated the characterization of a CMV (CyCMV) that is unique to cynomolgus macaques [108,109]. Cynomolgus macaques are used in kidney transplantation studies [110], evaluation of pharmacological safety [111], bone remodelling and osteoporosis [112], cardiovascular research [113] and viral pathogenesis [114,115].…”