Rhesus CMV: an emerging animal model for human CMV

Human CMV is the predominant infectious cause of congenital birth defects and an opportunistic pathogen in immunosuppressed individuals, including AIDS patients. Most individuals are infected early during their life followed by life-long latent infection. During this latent phase, frequent reactivation and antigen production continue to stimulate the immune system. While the immune response is able to control the virus, it is unable to eradicate it. Moreover, super-infection by different CMV strains has been observed despite a strong immune response. Long-term immune stimulation by CMV has also been implicated in immune senescence and chronic conditions such as atherosclerosis. CMVs are highly species-specific and the relatedness of CMV genomes exactly mirrors the relatedness of their hosts. Thus, each CMV species is highly adapted to its respective host species, but is unable to infect other, even closely related hosts. While fascinating from an evolutionary perspective, this host restriction prevents studying HCMV in experimental animals. Exceptions are severely immunocompromised mice, e.g. SCID mice, or SCID/NOD mice, which might allow partial reconstitution of CMV infection in rodents. More practical however, is to study CMVs in their natural host, e.g. murine, rat or guinea pig CMVs. However, while these small animal models have many advantages, such as the availability of inbred animals as well as lower cost, the limited homology of the viral genomes with HCMV limits the functional analysis of homologous gene products. The closest relative to HCMV is chimpanzee CMV (CCMV), but this is not a practical animal model since chimps are a protected species, extremely expensive and of very limited availability. In contrast, rhesus macaques are a more widely used experimental animal species and, while more distant than CCMV, rhesus CMV (RhCMV) contains most of the HCMV gene families thus allowing the study of their role in acute and latent CMV infection. In this review we will discuss the current state of developing RhCMV as a model for HCMV.     

AA‐type amyloidosis in association with non‐Hodgkin's lymphoma following CMV viremia: Autopsy case

Amyloidosis in non‐Hodgkin's lymphoma (NHL) is known to be of the AL type, and AA‐type amyloidosis in NHL is extremely rare. Herein is reported an autopsy case of follicular lymphoma that transformed to diffuse large B‐cell lymphoma (DLBCL) in a relapse associated with systemic AA amyloidosis. CMV infection in an immunocompromised state with chemotherapy against DLBCL may have been involved in amyloid accumulation. The serum amyloid A (SAA)1 gene polymorphism, SAA1.2/1.3, might have also been another factor in this case, considering the risk of AA amyloidosis in Japanese patients with rheumatoid arthritis.     

Why the elderly appear to be more severely affected by COVID‐19: The potential role of immunosenescence and CMV

The significantly higher mortality rates seen in the elderly compared with young children during the coronavirus disease 2019 (Covid‐19) pandemic is likely to be driven in part by an impaired immune response in older individuals. Cytomegalovirus (CMV) seroprevalence approaches 80% in the elderly. CMV has been shown to accelerate immune ageing by affecting peripheral blood T cell phenotypes and increasing inflammatory mediated cytokines such as IL‐6. The elderly with pre‐existing but clinically silent CMV infection may therefore be particularly susceptible to severe Covid‐19 disease and succumb to a cytokine storm which may have been promoted by CMV. Here, we evaluate the potential role of CMV in those with severe Covid‐19 disease and consider how this relationship can be investigated in current research studies.     

Evaluation of the new LIAISON® CMV IgG,IgM and IgG Avidity II assays

BackgroundThe diagnosis of CMV infection is challenging and the quality of serological laboratory testing is critical, especially in pregnancy and in the determination of transplant recipients and donors serostatus.ObjectivesEvaluate the performances of the new LIAISON^® CMV II line: LIAISON^® CMV IgG II, LIAISON^® CMV IgM II and LIAISON^® CMV IgG Avidity II in comparison with the routine methods used in our laboratory.Study designThe evaluation of LIAISON^® CMV IgG II and LIAISON^® CMV IgM II was performed on both prospective routine samples and retrospective selected samples for a total of 383 sera. CMV IgG avidity was assessed with 88 samples.ResultsThe overall agreement was 98.8% for the IgG and 95% for the IgM on the routine population. On selected retrospective samples, excellent agreement was found in the seronegative and past infection groups. In the recent infection group, discordances were observed in 7.1% of IgG and 13.1% of IgM. No recent infection was missed with LIAISON^®. Avidity agreement with VIDAS^® was 81%. On 51 sera with a known time of infection, no high avidity was found in the group infected for less than 3 months and 82% of the samples showed a high avidity in the group infected for more than 3 months.ConclusionThe performances of the fully automated LIAISON^® CMV II line assays are comparable to those of the reference methods used in our lab for both prospective and selected populations. This new CMV line is a useful tool for the diagnosis of CMV infections and CMV immune status in clinical settings     

Predictive value of cytomegalovirus viraemia for the occurrence of CMV organ involvement in AIDS

In HIV-infected patients, the presence of cytomegalovirus (CMV) viraemia is predictive of the development of acquired immunodeficiency syndrome (AIDS), but it is not known whether it predicts further occurrence of CMV organ involvement. To assess the predictive value of CMV viraemia in the occurrence of CMV organ involvement, CMV blood cultures were performed at the onset of AIDS in 71 patients. They were prospectively followed up for at least 6 months, with a mean of 16.6 +/- 7 months (6-36 months). CMV viraemia was present in 28/71 patients (39.5%) at the onset of AIDS. CMV organ involvement occurred in 18/71 patients (25.4%) after 8.7 +/- 3.3 months. Fourteen of the 28 patients (50%) with early CMV viraemia developed CMV organ involvement after 7.7 +/- 6.3 months as compared with 4/43 patients (9.3%) who were not viraemic at the onset of AIDS with a mean follow-up of 11.8 +/- 3.8 months (P less than 0.001). At the time of CMV organ involvement, CMV viraemia, however, was present in 94.4% of the cases. No differences in survival was observed between initially viraemic and non-viraemic patients. No difference has found in mean CD4 cell count between viraemic and non-viraemic patients. This high predictive value of early CMV viraemia in AIDS for the occurrence of CMV organ involvement underlines the need for repeated search for CMV organ involvement when CMV viraemia is detected, and for less toxic antiviral drugs that might be used earlier.     

Asymptomatic CMV infections in long‐term renal transplant recipients are associated with the loss of FcRγ from LIR‐1+ NK cells

While it is established that cytomegalovirus (CMV) disease affects NK‐cell profiles, the functional consequences of asymptomatic CMV replication are unclear. Here, we characterize NK cells in clinically stable renal transplant recipients (RTRs; n = 48) >2 years after transplantation. RTRs and age‐matched controls (n = 32) were stratified by their CMV serostatus and the presence of measurable CMV DNA. CMV antibody or CMV DNA influenced expression of NKG2C, LIR‐1, NKp30, NKp46, and FcRγ, a signaling adaptor molecule, on CD56^dim NK cells. Phenotypic changes ascribed to CMV were clearer in RTRs than in control subjects and affected NK‐cell function as assessed by TNF‐α and CD107a expression. The most active NK cells were FcRγ^–LIR‐1⁺NKG2C^– and displayed high antibody‐dependent cell cytotoxicity responses in the presence of immobilized CMV glycoprotein B reactive antibody. However, perforin levels in supernatants from RTRs with active CMV replication were low. Overall we demonstrate that CMV can be reactivated in symptom‐free renal transplant recipients, affecting the phenotypic, and functional profiles of NK cells. Continuous exposure to CMV may maintain and expand NK cells that lack FcRγ but express LIR‐1.     

Determination of CMV placentitis

 Cytomegalovirus (CMV) infection constitutes an important cause of intrauterine death. In the present study CMV infection of placentas resulting from intrauterine deaths was assessed by immunohistochemistry and by the polymerase chain reaction (PCR). Among 32 cases of chronic villitis examined, 7 were found by PCR to be associated with CMV infection, although light microscopic examination revealed only 3 of them, while 4 had shown positive immunohistochemical staining. In conclusion, CMV may be considered to be a relatively common cause of placentitis, and PCR is a helpful tool in confirming the nature of the disease. Received: 24 June 1997 / Accepted: 10 September 1997     

生物素─链霉亲和素系统在检测巨细胞病毒抗体中的应用

本文用自制ＣＭＶ抗原和生物素－链霉亲和素系统试剂，通过最适条件的对比，建立了检测人血清中抗巨细胞病毒ＩｇＭ、ＩｇＡ类抗体的ＢＳＡ－ＥＬＩＳＡ，并与普通ＥＬＩＳＡ作比较，结果表明，ＢＳＡ－ＥＬＩＳＡ的非特异性吸附明显低于普通ＥＬＩＳＡ，与普通ＥＬＩＳＡ相比，抗体效价分别提高５和７倍，阳性率分别提高６８％和１５３．５％。在实际工作中曾用ＢＳＡ－ＥＬＩＳＡ检测临床样品１６５份，就所得结果进行分析。表明ＢＳＡ－ＥＬＩＳＡ检测ＣＭＶＩｇＭ和ＩｇＡ可提高特异性和灵敏度，值得推广应用。     

生物素─链霉亲和素系统在检测巨细胞病毒抗体中的应用

本文用自制ＣＭＶ抗原和生物素－链霉亲和素系统试剂，通过最适条件的对比，建立了检测人血清中抗巨细胞病毒ＩｇＭ、ＩｇＡ类抗体的ＢＳＡ－ＥＬＩＳＡ，并与普通ＥＬＩＳＡ作比较，结果表明，ＢＳＡ－ＥＬＩＳＡ的非特异性吸附明显低于普通ＥＬＩＳＡ，与普通ＥＬＩＳＡ相比，抗体效价分别提高５和７倍，阳性率分别提高６８％和１５３．５％。在实际工作中曾用ＢＳＡ－ＥＬＩＳＡ检测临床样品１６５份，就所得结果进行分析。表明ＢＳＡ－ＥＬＩＳＡ检测ＣＭＶＩｇＭ和ＩｇＡ可提高特异性和灵敏度，值得推广应用。     

Brain‐resident memory CD8+ T cells induced by congenital CMV infection prevent brain pathology and virus reactivation

Congenital HCMV infection is a leading infectious cause of long‐term neurodevelopmental sequelae. Infection of newborn mice with mouse cytomegalovirus (MCMV) intraperitoneally is a well‐established model of congenital human cytomegalovirus infection, which best recapitulates the hematogenous route of virus spread to brain and subsequent pathology. Here, we used this model to investigate the role, dynamics, and phenotype of CD8⁺ T cells in the brain following infection of newborn mice. We show that CD8⁺ T cells infiltrate the brain and form a pool of tissue‐resident memory T cells (T_RM cells) that persist for lifetime. Adoptively transferred virus‐specific CD8⁺ T cells provide protection against primary MCMV infection in newborn mice, reduce brain pathology, and remain in the brain as T_RM cells. Brain CD8⁺ T_RM cells were long‐lived, slowly proliferating cells able to respond to local challenge infection. Importantly, brain CD8⁺ T_RM cells controlled latent MCMV and their depletion resulted in virus reactivation and enhanced inflammation in brain.     

Natural killing (NK) of cytomegalovirus (CMV)-infected fibroblasts: a comparison between two strains of CMV, uninfected fibroblasts, and K562 cells

Spontaneous cytolysis of uninfected human fibroblasts (HF), K562 cells, and HF cells infected with cytomegalovirus (CMV) was associated with nonadherent peripheral blood leukocytes (PBL) that passed through a nylon wool column, and rosetted with sheep erythrocytes at low affinity; cytolysis was further associated with enriched preparations of large granular lymphocytes (LGL). The Leu-7 marker did not correlate as a cell phenotype with functional activity in normal donors. The HF cells infected with the AD169 strain of CMV were as sensitive to cytolysis as K562 cells, although the kinetics of cytolysis differed; HF cells infected with the Davis strain of CMV were generally less sensitive to cytolysis than uninfected fibroblasts. Equivalent amounts of interferon were detected in NK assays containing Davis targets, AD169 targets, or K562 cells; interferon was not detected in NK assays of HF cells. Neither uninfected nor infected HF cells competed effectively against 51Cr-labeled K562 cells in cold competition experiments; K562 cells, however, competed effectively against 51Cr-labeled AD169-CMV targets. Uninfected HF cells were efficient competitors of AD169-CMV targets. Davis-CMV-infected cells were less effective, however, than uninfected HF cells in competition experiments, suggesting that fewer receptors for NK cells were present on these targets.     

Ex vivo monitoring of human cytomegalovirus‐specific CD8+ T‐Cell responses using the QuantiFERON®‐CMV assay in allogeneic hematopoietic stem cell transplant recipients attending an Irish hospital

Reconstitution of human cytomegalovirus (HCMV) T‐cell immunity is crucial in hematopoietic stem cell transplant (HSCT) recipients. The QuantiFERON®‐CMV assay for cellular HCMV‐specific immunity was evaluated in allogeneic HSCT recipients (n = 43) and patients with hematological malignancies (n = 29) attending a tertiary‐care Irish hospital. An intracellular cytokine (ICC) assay correlated with the QuantiFERON®‐CMV assay. Although there was agreement between HCMV seropositivity and QuantiFERON®‐CMV assay, six HCMV seropositive immunosuppressed patients with hematological malignancy had negative QuantiFERON®‐CMV results. The 43 HSCT recipients were classified as high risk (D^?/R⁺) (n = 18), intermediate risk (D⁺/R⁺ and D⁺/R^?) (n = 17), and low risk (D^?/R^?) (n = 8). During episodes of HCMV DNAemia no evidence of HCMV‐specific immunity was found using the QuantiFERON®‐CMV assay. Furthermore, the recovery of HCMV‐specific CD8⁺ T‐cell responses in high‐risk seropositive recipients of matched unrelated donors was severely delayed, a mean of 200 (SD = 117) days compared to 58 (SD = 23) days for sibling donors (P ≤ 0.028). In addition, three patients with late HCMV infection (infection >100 days post‐transplant) had delayed reconstitution of HCMV‐specific CD8⁺ T cells. Interestingly, two recipients (R⁺/D^?) developed rapid immune reconstitution by days 15 and 36 post‐HSCT, suggesting HCMV‐specific T‐cell lymphopoiesis of recipient origin. Levels of CD8⁺ T‐cell immunity in HCMV seropositive HSCT recipients were lowest following HSCT. A high number (33%) of indeterminate results was observed immediately after transplantation. Patients with indeterminate QuantiFERON®‐CMV results had low levels of HCMV‐specific CD8⁺ T cells. J. Med. Virol. 82:433–440, 2010. © 2010 Wiley‐Liss, Inc.     

CMV and natural killer cells: shaping the response to vaccination

Cytomegaloviruses (CMVs) are highly prevalent, persistent human pathogens that not only evade but also shape our immune responses. Natural killer (NK) cells play an important role in the control of CMV and CMVs have in turn developed a plethora of immunoevasion mechanisms targeting NK cells. This complex interplay can leave a long‐lasting imprint on the immune system in general and affect responses toward other pathogens and vaccines. This review aims to provide an overview of NK cell biology and development, the manipulation of NK cells by CMVs and the potential impact of these evasion strategies on responses to vaccination.     

Going beyond serology for stratifying the risk of CMV infection in transplant recipients

Knowledge of donor and recipient (D/R) cytomegalovirus (CMV) serostatus is critical for risk stratification of CMV infection and disease in transplant recipients, particularly in the solid organ transplantation (SOT) setting. Despite its broad availability and the success of it use, the risk stratification based on the D/R serostatus is not free of limitations since there are a nondepreciable number of patients that are not accurately categorized by this approach. In fact, up to 20% of seropositive SOT recipients, classically considered at intermediate risk, develop episodes of CMV infection and disease after transplantation. Here, we provide an overview of additional donor and recipient factors that may have utility in identifying patients at risk for post‐transplant CMV infection. Specifically, we summarize our current understanding regarding the potential use of use CMV‐specific T‐cell‐mediated immunity, neutralizing antibodies and host genetics that may influence the risk of CMV infection and disease. We provide an overview of the benefits and limitations associated with using these immunological factors in risk stratification and propose specific variables that could be analyzed at the pretransplant evaluation to improve the identification of patients with increased individual susceptibility.