Update on cytomegalovirus in transplant recipients: new agents, prophylaxis, and cell-mediated immunity

Reexploring cytomegalovirus serology in allogeneic hematopoietic cell transplantation

PURPOSE OF REVIEW

Discuss the recent evidence on cytomegalovirus (CMV) serology in allogeneic hematopoeic cell transplant (HCT) recipients.

RECENT FINDINGS

Whereas the role CMV-specific cellular mediated immunity has recently emerged as an important factor of CMV DNAemia posttransplant, the value of CMV serology has remained unchanged through decades, associated with donor selection and posttransplant prophylactic and monitoring strategies. In this review, we describe and discuss the emerging reports on the association between the magnitude of pretransplant CMV immunoglobulin G (IgG) titer and the posttransplant incidence of CMV DNAemia, as CMV IgG titer could become an additional tool in CMV risk assessment in the future.

SUMMARY

Pretransplant recipient CMV serology may have significant implications in posttransplant CMV reactivation in allogeneic HCT recipients.

Evaluation of an automated real-time transcription-mediated amplification (TMA) assay for detection and quantification of cytomegalovirus DNA in different clinical specimens

BACKGROUND

Reliable and fast detection and quantification of human cytomegalovirus (CMV) DNA in various diagnostic specimens is essential for care of immunocompromised or congenitally infected individuals.

OBJECTIVES

To evaluate the analytical and clinical performance of the Panther Aptima® CMV (Hologic) quantitative real-time transcription mediated amplification (TMA) assay.

STUDY DESIGN

Performance of the TMA assay run on the Hologic Panther Fusion was analysed for 32 proficiency testing samples and 21 quantitative reproducibility panel samples; additionally, we compared results of TMA assay and routine quantitative real-time PCR assays ("PCR-A"= Biomérieux CMV R-gene® or "PCR-B"= Laboratory-developed CMV-PCR) in 518 diagnostic specimens (254 plasma, 120 EDTA whole blood, 43 urine, 45 amniotic fluid and 56 breast milk) at two university hospital laboratories.

RESULTS

All proficiency panel samples were correctly identified and quantified by the TMA assay; replicate testing of the reproducibility panel samples showed good reproducibility within and between the two laboratories. Sensitivity in plasma and WB was higher for the TMA assay detecting low-level CMV-DNAemia in samples tested negative by routine PCR. Quantitative CMV-DNAemia values correlated well between TMA and real-time PCR. Similarly, urine, AF and BM specimens showed a high rate of concordant results (91%, 98% and 98%, respectively) among TMA and PCR with good correlation of quantitative values.

CONCLUSION

The performance of the Aptima® CMV TMA assay for viral blood load testing compared well to established real-time PCRs. In addition, it can be useful for diagnostics in urine, amniotic fluid and breast milk specimens.

Letermovir Rescue Therapy in Kidney Transplant Recipients with Refractory/Resistant CMV Disease

(1) Background: CMV infections remain a problem after kidney transplantation, particularly if patients are refractory or resistant (r/r) to treatment with valganciclovir (VGCV) or ganciclovir (GCV). (2) Methods: In a single-center retrospective study, kidney transplant recipients (KTR) receiving letermovir (LTV) as rescue therapy for VGCV-/GCV-r/r CMV disease were analyzed regarding CMV history, immunosuppression, and outcomes. (3) Results: Of 201 KTR treated for CMV between 2017 and 2022, 8 patients received LTV following treatment failure with VGCV/GCV. All patients received CMV prophylaxis with VGCV according to the center's protocol, and 7/8 patients had a high-risk (D+/R-) CMV constellation. In seven of eight cases, rising CMV levels occurred during prophylaxis. In seven of eight patients, a mutation in UL97 associated with a decreased response to VGCV/GCV was detected. In four of eight patients, LTV resulted in CMV clearance after 24 ± 10 weeks (16-39 weeks), two of eight patients stabilized at viral loads <2000 cop/mL (6-20 weeks), and two of eight patients developed LTV resistance (range 8-10 weeks). (4) Conclusion: LTV, which is currently evaluated for CMV prophylaxis in kidney transplantation, also shows promising results for the treatment of patients with VGCV/GCV resistance despite the risk of developing LTV resistance. Additional studies are needed to further define its role in the treatment of patients with CMV resistance.

Updates in hematopoietic cell transplant and cellular therapies that enhance the risk for opportunistic infections

BACKGROUND

Infectious disease physicians may be asked to evaluate and manage a variety of infections in immunocompromised hosts undergoing hematopoietic cell transplant (HCT) and cellular therapies. Over the last decade, several advances in cellular therapy have occurred, with implications for the types of infectious complications that may be seen.

AIMS

The purpose of this review is to update the infectious disease physician on newer advances in HCT and cellular therapy, including haploidentical transplant, expanding indications for transplant in older individuals and children, and chimeric antigen receptor T-cells. We will review how these advances might influence infectious disease complications following HCT. We will also provide a perspective that infectious disease physicians can use to evaluate the degree of immune suppression in an individual patient to help determine the type of infections that may be encountered.

Raf1 promotes successful Human Cytomegalovirus replication and is regulated by AMPK-mediated phosphorylation during infection

Raf1 is a key player in growth factor receptor signaling, which has been linked to multiple viral infections, including Human Cytomegalovirus (HCMV) infection. Although HCMV remains latent in most individuals, it can cause acute infection in immunocompromised populations such as transplant recipients, neonates, and cancer patients. Current treatments are suboptimal, highlighting the need for novel treatments. Multiple points in the growth factor signaling pathway are important for HCMV infection, but the relationship between HCMV and Raf1, a component of the mitogen-activated protein kinase (MAPK) cascade, is not well understood. The AMP-activated protein kinase (AMPK) is a known regulator of Raf1, and AMPK activity is both induced by infection and important for HCMV replication. Our data indicate that HCMV infection induces AMPK-specific changes in Raf1 phosphorylation, including increasing phosphorylation at Raf1-Ser621, a known AMPK phospho-site, which results in increased binding to the 14-3-3 scaffolding protein, an important aspect of Raf1 activation. Inhibition of Raf1, either pharmacologically or via shRNA or CRISPR-mediated targeting, inhibits viral replication and spread in both fibroblasts and epithelial cells. Collectively, our data indicate that HCMV infection and AMPK activation modulate Raf1 activity, which are important for viral replication.

Overlapping Infection by Strongyloides spp. and Cytomegalovirus in the Immunocompromised Host: A Comprehensive Review of the Literature

Strongyloides and cytomegalovirus co-infections are rarely reported, even though they are distinguished by high morbidity and mortality, especially in immunocompromised hosts. We narratively reviewed the literature on reported cases of Strongyloides and CMV co-infections in immunosuppressed patients. Most cases occurred in males with a median age of 47 (IQR, 37-59). Strongyloides/CMV co-infections occurred among immunocompromised hosts, especially in solid organ transplants and hematological or rheumatological diseases. Most of the patients underwent a course of steroid treatment before the diagnosis of co-infections. Other common immunomodulatory agents were tacrolimus and mycophenolate. The first clinical manifestations of co-infections were mainly gastrointestinal, followed by respiratory symptoms. CMV was, in most patients, co-infected with an isolated reactivation, although Strongyloides manifested especially as hyperinfection syndrome. Ganciclovir and ivermectin are the mainstays of CMV and Strongyloides treatment. However, the treatment mortality reported in this narrative review is around 52.4%. Interestingly secondary bacterial infections are common in CMV/Strongyloides-infected patients.

Strongyloides spp. and Cytomegalovirus Co-Infection in Patient Affected by Non-Hodgkin Lymphoma

To our knowledge, we have described the first case of Strongyloides/Cytomegalovirus (CMV) concomitant infection that occurred in a European country. The patient was a 76-year-old woman affected by relapsed non-Hodgkin lymphoma who presented interstitial pneumonia with a rapidly progressive worsening of respiratory insufficiency, leading to cardiac dysfunction and consequent death. CMV reactivation is a common complication in immunocompromised patients, while hyperinfection/disseminated strongyloidiasis (HS/DS) is rare in low endemic regions, but has been widely described in Southeast Asia and American countries. HS and DS are two consequences of the failure of infection control by the immune system: HS is the uncontrolled replication of the parasite within the host and DS the spreading of the L3 larvae in organs other than the usual replication sites. Only a few cases of HS/CMV infection have been reported in the literature, and only in one patient with lymphoma as an underlying disease. The clinical manifestations of these two infections overlap, usually leading to a delayed diagnosis and a consequent poor outcome.

Comparison of intracellular cytokine staining versus an ELISA-based assay to assess CMV-specific cell-mediated immunity in high-risk kidney transplant recipients

The best method for monitoring cytomegalovirus (CMV)-specific cell-mediated immunity (CMV-CMI) among high-risk kidney transplant (KT) recipients remains uncertain. We assessed CMV-CMI by intracellular cytokine staining (ICS) by flow cytometry and a commercial interferon (IFN)-γ release assay (QuantiFERON®-CMV [QTF-CMV]) at posttransplant months 3, 4, and 5 in 53 CMV-seropositive KT recipients that had received induction therapy with antithymocyte globulin (ATG) and a 3-month course of valganciclovir prophylaxis. The discriminative capacity (areas under receiver operating characteristics curve [auROCs]) and diagnostic accuracy to predict immune protection against CMV infection from the discontinuation of prophylaxis to month 12 were compared between both methods. There was significant although moderate correlations between CMV-specific IFN-γ-producing CD8⁺ T-cell counts enumerated by ICS and IFN-γ levels by QTF-CMV at months 3 (rho: 0.493; p = 0.005) and 4 (rho: 0.440; p = 0.077). The auROCs for CMV-specific CD4⁺ and CD8⁺ T-cells by ICS were nonsignificantly higher than that of QTF-CMV (0.696 and 0.733 vs. 0.678; p = 0.900 and 0.692, respectively). The optimal cut-off of ≥0.395 CMV-specific CD8⁺ T-cells yielded a sensitivity of 86.4%, specificity of 54.6%, positive predictive value of 79.2% and negative predictive value of 66.7% to predict protection. The corresponding estimates for QTF-CMV (IFN-γ levels ≥0.2 IU/mL) were 78.9%, 37.5%, 75.0%, and 42.9%, respectively. The enumeration of CMV-specific IFN-γ-producing CD8⁺ T-cells at the time of cessation of prophylaxis performed slightly better than the QTF-CMV assay to predict immune protection in seropositive KT recipients previously treated with ATG.

Polygenic Innate Immunity Score to Predict the Risk of Cytomegalovirus Infection in CMV D+/R- Transplant Recipients. A Prospective Multicenter Cohort Study

Several genetic polymorphisms of the innate immune system have been described to increase the risk of cytomegalovirus (CMV) infection in transplant patients. The aim of this study was to assess the impact of a polygenic score to predict CMV infection and disease in high risk CMV transplant recipients (heart, liver, kidney or pancreas). On hundred and sixteen CMV-seronegative recipients of grafts from CMV-seropositive donors undergoing heart, liver, and kidney or pancreas transplantation from 7 centres were prospectively included for this purpose during a 2-year period. All recipients received 100-day prophylaxis with valganciclovir. CMV infection occurred in 61 patients (53%) at 163 median days from transplant, 33 asymptomatic replication (28%) and 28 CMV disease (24%). Eleven patients (9%) had recurrent CMV infection. Clinically and/or functionally relevant single nucleotide polymorphisms (SNPs) from TLR2, TLR3, TLR4, TLR7, TLR9, AIM2, MBL2, IL28, IFI16, MYD88, IRAK2 and IRAK4 were assessed by real time polymerase chain reaction (RT-PCR) or sequence-based typing (PCR-SBT). A polygenic score including the TLR4 (rs4986790/rs4986791), TLR9 (rs3775291), TLR3 (rs3775296), AIM2 (rs855873), TLR7 (rs179008), MBL (OO/OA/XAO), IFNL3/IL28B (rs12979860) and IFI16 (rs6940) SNPs was built based on the risk of CMV infection and disease. The CMV score predicted the risk of CMV disease with an AUC of the model of 0.68, with sensitivity and specificity of 64.3 and 71.6%, respectively. Even though further studies are needed to validate this score, its use would represent an effective model to develop more robust scores predicting the risk of CMV disease in donor/recipient mismatch (D+/R-) transplant recipients.

Viral Nucleases from Herpesviruses and Coronavirus in Recombination and Proofreading: Potential Targets for Antiviral Drug Discovery

In this review, we explore recombination in two very different virus families that have become major threats to human health. The Herpesviridae are a large family of pathogenic double-stranded DNA viruses involved in a range of diseases affecting both people and animals. Coronaviridae are positive-strand RNA viruses (CoVs) that have also become major threats to global health and economic stability, especially in the last two decades. Despite many differences, such as the make-up of their genetic material (DNA vs. RNA) and overall mechanisms of genome replication, both human herpes viruses (HHVs) and CoVs have evolved to rely heavily on recombination for viral genome replication, adaptation to new hosts and evasion of host immune regulation. In this review, we will focus on the roles of three viral exonucleases: two HHV exonucleases (alkaline nuclease and PolExo) and one CoV exonuclease (ExoN). We will review the roles of these three nucleases in their respective life cycles and discuss the state of drug discovery efforts against these targets.

Managing sepsis in the era of precision medicine: challenges and opportunities

INTRODUCTION

Precision medicine is a medical model in which decisions, practices, interventions and therapies are tailored to the individual patient based on their predicted response or risk of disease. Sepsis is a life-threatening condition characterized by immune system dysregulation whose pathophysiology remains incompletely understood. There is much hope that precision medicine can lead to better outcomes in patients with sepsis.

AREAS COVERED

In this review from a comprehensive literature search in PubMed for English-language studies conducted in adults, we highlight recent advances in the diagnosis and treatment of sepsis of bacterial origin in adults using precision medicine approaches including rapid diagnostic tests, predictive biomarkers, genomic methods, rapid antimicrobial susceptibility testing, and monitoring cell mediated immunity. Challenges and directions for future research are also discussed.

EXPERT OPINION

Current diagnostic testing in sepsis relies primarily on conventional cultures (e.g. blood cultures), which are time-consuming and may delay critical therapeutic decisions. Nonculture-based techniques including nucleic acid amplification technologies (NAAT), other molecular methods (biomarkers), and genomic sequencing offer promise to overcome some of the inherent limitations seen with culture-based techniques.

Pulmonary Complications After Pediatric Stem Cell Transplant

The number of disorders that benefit from hematopoietic stem cell transplantation (HSCT) has increased, causing the overall number of HSCT to increase accordingly. Disorders treated by HSCT include malignancy, benign hematologic disorders, bone marrow failure syndromes, and certain genetic diagnoses. Thus, understanding the complications, diagnostic workup of complications, and subsequent treatments has become increasingly important. One such category of complications includes the pulmonary system. While the overall incidence of pulmonary complications has decreased, the morbidity and mortality of these complications remain high. Therefore, having a clear differential diagnosis and diagnostic workup is imperative. Pulmonary complications can be subdivided by time of onset and whether the complication is infectious or non-infectious. While most infectious complications have clear diagnostic criteria and treatment courses, the non-infectious complications are more varied and not always well understood. This review article discusses pulmonary complications of HSCT recipients and outlines current knowledge, gaps in knowledge, and current treatment of each complication. This article includes some adult studies, as there is a significant paucity of pediatric data.