Correlation between CMV genotypes, multiple infections with herpesviruses (HHV-6, 7) and development of CMV disease in kidney recipients in Kuwait

Significance of Cytomegalovirus gB Genotypes in Adult Patients Undergoing Hematopoietic Stem Cell Transplantation: Insights from a Single-Centre Investigation

INTRODUCTION

Cytomegalovirus (CMV) infection is a major clinical issue after allogeneic hematopoietic stem cell transplantation (HSCT). The CMV envelope glycoproteins are key in viral pathogenesis; the glycoprotein B (gB) encoded by the UL55 gene might be an important determinant of viral virulence and disease severity marker in patients treated with allogeneic HSCT. Our aim was to investigate the molecular diversity of CMV gB and inquire into the associations between UL55 gene variations and clinical manifestations in adult patients treated with allogeneic HSCT.

RESULTS

The most prevalent genotypes were gB1 and gB4 (11/27, 40.7%). Patients with genotype gB1 infection had earlier platelet engraftment (p < 0.033) and less frequent minimal/measurable residual disease post HSCT than those without this genotype. Patients with gB4 glycoprotein infection had a significantly lower CD4+/CD8+ ratio at D90 (p < 0.026). Interestingly, patients with gB5 glycoprotein infection had shorter overall survival from base condition diagnosis (p < 0.042), as well as shorter overall survival after HSCT (p < 0.036). Acute GvHD was noted more frequently in those with mixed-genotype infection (p = 0.047).

MATERIAL AND METHODS

The study included fifty-nine adult patients treated with allogeneic HSCT. Peripheral venous blood was sampled typically per week, with detection of CMV performed by quantitative real-time PCR. Multiplex nested PCR was used to determine specific gB genotypes, which were then statistically compared vis-à-vis specific clinical variables.

CONCLUSIONS

Our study points to variations in the viral UL55 locus imparting both beneficial (earlier platelet engraftment, less frequent MRD post HSCT) and adverse effects (shorter overall survival, more frequent acute GvHD, less frequent 100% chimerism at day 90) to the transplanted host. Comprehensive molecular investigations are necessary to validate this apparent duality, as the potential benefits of CMV could perhaps be utilized for the benefit of the patient in the future.

Differential diagnosis of fever and rash cases negative for measles and rubella to complement surveillance activities

In the quest to eliminate measles virus (MV) and rubella virus (Ruv), every suspected case must be properly identified and diagnosed. Since 2017, in Milan (Italy), a total of 978 measles and rubella suspected cases (fever and rash) were investigated and 310 were not laboratory confirmed (discarded cases). To improve surveillance activities, we investigated the presence in discarded cases of 8 other viral pathogens commonly associated with rash: human herpesvirus 6 (HHV-6) and 7 (HHV-7), parvovirus B19 (B19V), enterovirus (EV), Epstein-Barr virus (EBV), human adenovirus (HAdV), cytomegalovirus (HCMV), and SARS-CoV-2. Differential diagnosis was carried out on 289 discarded cases by multiplex real-time PCR assays. At least one pathogen was detected in 188 cases (65.1%) with HHV-7 being the most frequently detected virus. No difference in the number of detected infections overtime was observed and infections were identified in all age groups. As expected, most HHV-6, EV, HAdV, and HCMV-positive cases were found in children aged 0-4 years and HHV-7 was most frequent in the 15-39 age group. In light of the World Health Organization measles elimination goal, the introduction of laboratory methods for differential diagnosis is required for the final classification of clinically compatible cases. The used screening panel allowed us to increase the percentage of virus-positive cases to 87.5%, allowing us to clarify viral involvement and epidemiology, improve diagnosis, and strengthen surveillance activities. As all investigated pathogens were detected, this diagnostic panel was a suitable tool to complement MV and RuV surveillance activities.

Effectiveness of Topical Ganciclovir 2% Monotherapy Versus Combined Steroid Therapy in Cytomegalovirus Endotheliitis

We aimed to report the clinical manifestations of cytomegalovirus (CMV) corneal endotheliitis and the results of long-term treatment with topical ganciclovir 2% with and without steroids. This retrospective, interventional study included 15 eyes of 13 patients diagnosed with CMV corneal endotheliitis by positive CMV DNA and treated with long-term topical ganciclovir 2% eye drops at a tertiary referral center and the median follow-up period was 17 months. Ocular manifestations included keratic precipitates (KPs) (100%), elevated IOP (93.3%), iritis (60%), corneal edema (60%), and moth-eaten iris atrophy (60%). After long-term treatment, corneal edema, iritis, and KPs significantly decreased (effect size: 72%, 76% and 70%, respectively; p = 0.024, p = 0.006 and p < 0.001, respectively). Both the logMAR acuity and IOP significantly improved (median logMAR was 0.52 before treatment and 0.22 after treatment; median IOP was 42 mmHg before treatment and 12 mmHg after treatment; p = 0.001 and p < 0.001, respectively). The ECD was maintained (effect size: 80%), and the percentage of hexagonal cell ratio of endothelial cells significantly improved after treatment (effect size: 82%; p = 0.035). Fewer anti-glaucoma medications were used in the non-steroid group (effect size: 79%; p = 0.034). Long-term maintenance treatment with topical ganciclovir 2% monotherapy not only provides effective therapy and reduces recurrence, but also decreases the high IOP related to the combination of steroids used.

Molecular Detection and Glycoprotein B (UL55) Genotyping of Cytomegalovirus among Sudanese Renal Transplant Recipients

Background

Cytomegalovirus (CMV) is the most common opportunistic pathogen among renal transplants with significant morbidity and mortality. This study was designed to detect CMV DNA and to determine the frequency of different glycoprotein B (UL55) genotypes among Sudanese renal transplant recipients.

Methods

One hundred and four renal transplant recipients were included in this study. A blood specimen was collected from each recipient. DNA was extracted from plasma using the QIAamp DNA mini kit. CMV amplification and quantification were performed using CMV Real-RT Quant kits. Genotyping of human CMV gB was carried out by nested PCR and sequencing of the highly diverse region of gB.

Results

CMV DNA was detected in 40/104 (38.5%) of renal transplant recipients. The average of the CMV DNA viral load was 358 × 10⁴ copies/ml (6.5 log₁₀) ranging from 62 copies/ml (1.8 log₁₀) to 1.43 × 10⁸ copies/ml (9 log₁₀). CMV viremia was detected in 60% of recipients of less than 1–12 months, 17% of 13–24, 10% of 25–36, 5% of 37–48, and 8% in more than 48 months posttransplantation with no association (p = 0.296) between CMV viremia and postrenal transplantation time. The association between the type of immunosuppressive drugs and high viral loads (>1000 copies/ml) showed a significant difference (p = 0.05). The association between CMV loads of >1000 copies/ml and symptoms of CMV disease was highly significant (p ≤ 0.001). Fever 7 (41%), fever and leucopenia 6 (35%), and gastrointestinal disease 4 (24%) were the most common symptoms of CMV disease. CMV genotyping revealed 8 cases (80%) for gB3 and 2 cases (20%) for gB4 genotypes. The most frequent genotype among Sudanese renal transplant recipients was gB3.

Conclusions

The frequency of CMV DNA is high among Sudanese renal transplant recipients. CMV gB3 is the most predominant glycoprotein B genotype in Sudanese renal transplant recipients.

Common Polymorphisms in the Glycoproteins of Human Cytomegalovirus and Associated Strain-Specific Immunity

Human cytomegalovirus (HCMV), one of the most prevalent viruses across the globe, is a common cause of morbidity and mortality for immunocompromised individuals. Recent clinical observations have demonstrated that mixed strain infections are common and may lead to more severe disease progression. This clinical observation illustrates the complexity of the HCMV genome and emphasizes the importance of taking a population-level view of genotypic evolution. Here we review frequently sampled polymorphisms in the glycoproteins of HCMV, comparing the variable regions, and summarizing their corresponding geographic distributions observed to date. The related strain-specific immunity, including neutralization activity and antigen-specific cellular immunity, is also discussed. Given that these glycoproteins are common targets for vaccine design and anti-viral therapies, this observed genetic variation represents an important resource for future efforts to combat HCMV infections.

Active CMV and EBV infections in renal transplant recipients with unexplained fever and elevated serum creatinine

Proper identification of active cytomegalovirus (CMV) and Epstein-Barr virus (EBV) infections are helpful for monitoring antiviral treatment in transplant recipients. Qualitative and quantitative CMV, EBV DNA PCR techniques in the context of serological tests are performed for early detection and differentiation of active and latent CMV and EBV infections in renal transplantation. Basically, 129 renal transplanted recipients monitored carefully and hospitalized for unexplained elevated creatinine levels or high fever and 21 of their donors were studied. CMV DNA was detected in 63.5% of the febrile episodes following transplantation and in 46.42% of readmitted patients using qualitative PCR method. In the first group, 15% of the patients and in the second group 42.85% of the patients had copy numbers more than cutoff point (900 copies/mL). Cutoff point had 100% sensitivity and 82.5% specificity for active and symptomatic CMV infection. Only 15.5% of the subjects were positive for EBV infection by qualitative PCR method. Among them 5% had >2000 copies/mL and were symptomatic. One subject with a history of three times hospitalization had higher EBV viral load and developed post-transplant lymphoproliferative disorder. CMV load was significantly correlated with elevated creatinine levels (OR = 3.1, p = 0.006), abnormal heart sounds (OR = 4.7; p = 0.02) and hypertension (OR = 3.6; p = 0.03). Only qRT-PCR could differentiate between latent and active infections and might be clinically useful for monitoring symptomatic CMV and EBV infections and initiation of the antiviral therapy. Elevated creatinine levels, hypertension, and abnormal heart sounds could be considered as main manifestations of HCMV infection in kidney recipients.

Early HHV-6 replication is associated with morbidity non-related to CMV infection after kidney transplantation

Human herpesvirus type 6-(HHV-6) has been associated with morbidity after liver transplantation.

OBJECTIVE

The aim of this study was to determine the HHV-6 seroprevalence among donor-recipient pairs, analyze the incidence of early active infection, its clinical manifestation, interaction with CMV, and the related morbidity in the first year after kidney transplantation.

METHODS

46 donor-recipient pairs had IgG evaluated by ELISA before transplantation: HHV-6(Pambio - USA) and CMV-(Roche - USA). A frozen whole blood sample collected weekly (from the 1st to the 6th week) was retrospectively tested for HHV-6 viral load (VL) determination by real time quantitative PCR (qPCR, Nanogen - Italy). Patients were preemptively surveyed for CMV by pp65 antigenemia (Ag, APAAP, immunohistochemistry, Biotest - Germany) from the 4th to the 12th week after transplantation. Active infection was defined as qPCR-HHV6+ (viral-load/mL-VL) and Ag+ (+cells/100.000 granulocytes), for HHV-6 and CMV, respectively. DCMV was defined as simultaneous positive antigenemia and suggestive signs/symptoms. Concerning +qPCR-HHV6, associated factors, clinical manifestation, interaction with CMV and morbidity were searched.

RESULTS

Pre-transplant HHV-6 seroprevalence was significantly higher among kidney recipients compared to their donors (82.6x54.8%; p = 0.005 [3.9 (1.4-10.4)]). Active infection by this virus occurred in 26.1% (12/46), with no association with previous IgG (p = 0.412). Median VL was 125 copies/mL (53-11.264), and the median Ag was 21 +cells (2-740). There was no association between HHV-6 and CMV activation after transplantation (p = 0.441), neither concerning DCMV (p = 0.596). Median highest Ag+ and days of ganciclovir treatment were similar between qPCR-HHV6 + or - (p = 0.206 and p = 0.124, respectively). qPCR-HHV6+ was associated with higher incidence of bacterial (p = 0.009) and fungal (p = 0.001) infections, and higher number (p = 0.001) of hospital admission and longer duration of hospitalization over the first 6 and 12 months post-transplantation (p = 0.033 and p = 0.001).

CONCLUSION

Latent HHV-6 infection is more common among recipients than donors before transplantation. Early active infection by this pathogen after transplantation does not increase DCMV incidence or severity during the first 3 months of follow-up. However, early HHV-6 replication is associated with other infections and hospitalizations in the first year.

Lymphotropic herpesvirus DNA detection in patients with active CMV infection - a possible role in the course of CMV infection after hematopoietic stem cell transplantation

BACKGROUND

The natural history of cytomegalovirus (CMV) infection and disease in transplant recipients prompts researchers to look for other factors contributing to this infection. The ubiquity of lymphotropic herpesviruses (EBV, HHV-6, and HHV-7) and the possibility of their activation during immunosuppression may suggest their participation in progression of CMV infection in patients after hematopoietic stem cell transplantation (HSCT).

MATERIAL/METHODS

The presence of CMV, EBV, HHV-6 and HHV-7 was confirmed through detection of viral DNA isolated from leukocytes. Allo-HSCT recipients (n=55) were examined repeatedly within the average period of 14±7.3 months post-transplant.

RESULTS

CMV DNA was detected in 24% of samples, while EBV, HHV-6 and HHV-7 were detected in 20%, 15% and 14% of samples, respectively. Based on the presence of CMV infection at particular time-points (months) after transplantation, the recipients were divided into 3 groups: Group I (N=15) with persistent infection, Group II (N=20) with transient infection, and Group III (N=20) without CMV infection. In Group I, the mean CMV load was significantly higher than in Group II, and the clinical condition of Group I patients was poorer. All these patients manifested clinical symptoms, and all had episodes of GvHD. All Group I patients developed multiple infections; EBV in 80%, HHV-6 in 47% and HHV-7 in 87% of patients. In the remaining groups, with the exception of HHV-6 in group II, the frequency of infected patients was lower. In addition, CMV presence was often preceded by another herpesvirus.

CONCLUSIONS

The results suggest that other herpesviruses, mainly HHV-7, could predispose CMV to cause chronic infection.

Presence of human herpes virus 6 (HHV6) in pediatric lymphomas: impact on clinical course and association with cytomegalovirus infection

Background

Activation of herpes virus 6 (HHV6) has seen in Hodgkin's and non-Hodgkin's Lymphoma (HL&NHL) as a result of lymphoma associated immunosuppression. Multiple studies have suggested an association between both HHV6 and cytomegalovirus CMV for development of CMV disease affecting the pathogenesis of lymphoma. Therefore, this study investigated the frequency of HHV6, its impact on clinical manifestations of lymphoma and its possible association with risk for development of CMV infection in pediatric lymphoma patients.

Methods

Presence of HHV6 DNA and CMV DNA was investigated by PCR assay in both WBC's and plasma samples from 50 patients diagnosed with HL or NHL. CMV antibody titer was also determined in sera obtained from each patient. Twenty apparently healthy siblings were used as a control group.

Results

In a study group of 50 patients diagnosed with HL or NHL, 23/50 (46%) were found to be positive for herpes virus DNA (HHV6 or CMV) in WBC's or plasma by PCR assay and this was significantly higher than its presence in the pediatric control group 2/20 (10%) (p = 0.005). Ten out of these 23 (43%) were found to have active CMV infection. Fifty six percent of patients with CMV infection were found among NHL cases with B- subtype. The presence of both herpes viruses DNA was significantly associated with more frequent episodes of febrile neutropenia (median 3 episodes), absolute neutrophil count (< 0.8), lymphocytes (< 0.5), and low hemoglobin level (< 9.1), (p < 0.05).

Conclusion

The presence of HHV6 can be considered as a predicting indicator of cellular immunosuppression preceding the onset of CMV infection which may result in a severe outcome among pediatric lymphoma patients.

Sequence variability of human cytomegalovirus UL146 and UL147 genes in low-passage clinical isolates

OBJECTIVES

Human cytomegalovirus (HCMV) infects a number of organs and cell types in vivo. The different symptoms and tissue tropisms of HCMV infection perhaps result from the genetic polymorphism. A new region of DNA containing at least 19 open reading frames (ORFs - denoted UL133-151) was found in the low-passage HCMV clinical strain Toledo and several other low-passage clinical isolates, but not present in the HCMV laboratory strain AD169. Two of these genes, UL146 and UL147, encode proteins with sequence characteristics of CXC (alpha) chemokines, suggesting that they might influence the behavior of neutrophils during infection. This research was to study the sequence variability of UL146 and UL147 ORFs in HCMV clinical isolates and examine the possible associations between gene variability and the outcome of HCMV infection.

METHODS

UL146 and UL147 genes from strains obtained from suspected congenitally HCMV-infected infants were PCR amplified and sequenced.

RESULTS

High variability was found in UL146 and UL147 gene among HCMV clinical strains. However, the alpha chemokine motif in UL146 and UL147 genes was conserved in almost all sequences. According to the phylogenetic analysis, all sequences of UL146 in clinical isolates could be divided into three groups. All strains from congenital megacolon infants existed in G2A only, and all from asymptomatic infants existed in G2B peculiarly.

CONCLUSIONS

Sequence variability among HCMV clinical strains may affect the ability of UL146 and UL147 to attract human neutrophils and influence viral dissemination. No obvious linkage was observed between UL146 polymorphisms and outcome of suspected congenital HCMV infection.

Genomic variants among human cytomegalovirus (HCMV) clinical isolates: the glycoprotein n (gN) paradigm

Human cytomegalovirus (HCMV) clinical isolates display genetic polymorphisms, which are supposed to be implicated in strain-specific tissue tropism and HCMV-induced immunopathogenesis. One highly variable gene is ORF UL73, encoding for the envelope glycoprotein gN, which displays both a structural and an immunologic role as a component of the high-molecular weight complex gC-II. UL73 showed clustered polymorphisms, which originate four distinct genomic variants, denoted gN-1, gN-2, gN-3, and gN-4. This review reports the main features of gN genotypes and their potential implications on HCMV biologic properties. The clinical impact of gN variants is also discussed. This overview on gN clustered polymorphisms should be useful as a prototype model for a better understanding of the biologic and clinical relevance of HCMV clinical isolates genetic variability.

Genetic polymorphisms among human cytomegalovirus (HCMV) wild-type strains

Human cytomegalovirus (HCMV) clinical isolates display genetic polymorphisms in multiple genes. Some authors have suggested that those polymorphisms may be implicated in HCMV-induced immunopathogenesis, as well as in strain-specific behaviours, such as tissue-tropism and ability to establish persistent or latent infections. This review summarises the features of the main clustered HCMV polymorphic open reading frames and also briefly cites other variable loci within the viral genome. The implications of gene polymorphisms are discussed in terms of potentially advantageous higher fitness obtained by the strain, but also taking into account that the published data are often speculative. The last section of this review summarises and critically analyses the main literature reports about the linkage of strain specific genotypes with clinical manifestations of HCMV disease in different patient populations affected by severe cytomegalovirus infections, namely immunocompromised subjects and congenitally infected newborns.

Update on human herpesvirus 6 biology, clinical features, and therapy

Human herpesvirus 6 (HHV-6) is a betaherpesvirus that is closely related to human cytomegalovirus. It was discovered in 1986, and HHV-6 literature has expanded considerably in the past 10 years. We here present an up-to-date and complete overview of the recent developments concerning HHV-6 biological features, clinical associations, and therapeutic approaches. HHV-6 gene expression regulation and gene products have been systematically characterized, and the multiple interactions between HHV-6 and the host immune system have been explored. Moreover, the discovery of the cellular receptor for HHV-6, CD46, has shed a new light on HHV-6 cell tropism. Furthermore, the in vitro interactions between HHV-6 and other viruses, particularly human immunodeficiency virus, and their relevance for the in vivo situation are discussed, as well as the transactivating capacities of several HHV-6 proteins. The insight into the clinical spectrum of HHV-6 is still evolving and, apart from being recognized as a major pathogen in transplant recipients (as exemplified by the rising number of prospective clinical studies), its role in central nervous system disease has become increasingly apparent. Finally, we present an overview of therapeutic options for HHV-6 therapy (including modes of action and resistance mechanisms).