Cytomegalovirus glycoprotein B groups in human immunodeficiency virus-infected patients with incident retinitis

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.

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.

Combined genetic variants of human cytomegalovirus envelope glycoproteins as congenital infection markers

Background

Human cytomegalovirus (HCMV) is still considered to be the main viral cause of birth defects and long-term neurological and sensory sequelae following congenital infection.

Several Authors sustain a key role of HCMV envelope glycoproteins, such as gB, gN and gO - mainly involved in cell targeting, viral penetration and spread - as putative virulence factors. The genes coding for these glycoproteins possess hypervariable regions, resulting in a number of genetic variants in circulating clinical strains. Considering that the genetic polymorphisms underlying the specific differences between gB, gN and gO genotypes can influence the ability of HCMV to preferentially target specific host cells, it is very likely that they play an important role in defining HCMV infection outcome.

In the present study, we analysed HCMV gB, gN and gO gene polymorphisms in viral strains isolated from paediatric patients with congenital or post-natal infection, to investigate whether specific genetic variants may be associated with congenital infection.

Methods

The restriction fragment polymorphisms of genes coding for HCMV gB (UL55), gN (UL73) and gO (UL74) were investigated by analysing viral DNA extracted from 40 urine samples of as many paediatric patients with congenital or post-natal HCMV infection. Randomly selected samples were subjected to DNA sequencing and phylogenetic analysis. Statistical analysis was performed using Fisher’s exact test to assess the significance of single and combined glycoprotein genotypes frequency distribution. Statistical significance was considered at a P <0.05.

Results

While gB genomic variants were quite homogeneously represented in both paediatric groups, the gN4 genotype significantly prevailed in congenitally infected children (89.5 %) vs post-natally infected children (47.6 %), with a predominance of the gN4c variant (47.4 %). A similar trend was observed for gO3 (52.6 % vs 19 %).

Concerning genotypes association, a statistically significant (P = 0.037) gN4-gO3 combination was found specifically in the congenitally infected group.

Conclusions

The results indicate that the gN4 (mostly the gN4c variant) and gO3 combined genotypes could provide useful markers of congenital infection and represent suitable candidate molecules for prophylactic vaccine preparations.

Cytomegalovirus glycoprotein B genotypes in Mexican children and women

OBJECTIVE

Cytomegalovirus (CMV) is widely distributed and constitutes the main cause of congenital infections worldwide. CMV transmission during pregnancy represents one of the major impacts of this virus on public health. This study aimed at assessing glycoprotein B (gB) CMV genotypes in Mexican children and pregnant women, since there is limited information regarding CMV genomic diversity in Mexico.

METHODS

We analyzed CMV strains detected in Mexican children (n = 38) and women (n = 38) between 2001 and 2012. A fragment of the gB gene was amplified and sequenced, and genotypes were defined based on prototype sequences.

RESULTS

The gB1 genotype was detected more frequently in children (68.4%) compared to women (31.6%; p = 0.0028), while genotype 2 was more common in women (65.8%) compared to children (26.3%, p = 0.0012). Genotype 3 was uncommon in both groups (5.3 and 2.6%). Nucleotide sequences exhibited a high degree of similarity to prototype strains. However, we identified 17 distinct sequences that resulted in changes in the encoded amino acid sequence in four strains.

CONCLUSIONS

gB1 and gB2 are the most common strains associated with CMV infection in Mexican children and women. In addition, we found that the frequency for each genotype differed amongst them, possibly due to variability in transmission or reactivation dynamics.

Determination of cytomegalovirus prevalence and glycoprotein B genotypes among ulcerative colitis patients in ahvaz, iran

Background:

The human cytomegalovirus (HCMV) is a common pathogen which usually remains asymptomatic in the healthy adults; however, it can cause a symptomatic disease in the immunocompromised patients. The risk of infection with HCMV increases in ulcerative colitis (UC) patients as a result of receiving immunosuppressive agents.

Objectives:

This study aimed to determine the prevalence and the glycoprotein B genotypes of HCMV among the patients with HCMV disease superimposed on an UC flare that required hospitalization in Imam Khomeini Hospital in Ahvaz, Iran, during 2010- 2012.

Patients and Methods:

In this case-control study, formalin-fixed paraffin-embedded intestinal tissue samples were taken from 98 patients with UC disease including 53 males and 45 females (mean age ± standard deviation, 38.95 ± 17.93) and 67 control patients with noninflammatory disease who were referred to Imam Khomeini Hospital during 2010-2012. Detection of HCMV genome in intestinal samples was carried out by seminested polymerase chain reaction. Glycoprotein B genotypes were determined by sequencing.

Results:

Among 98 patients with UC, only 12 (12.2%) patients were positive for HCMV genome, while the HCMV genome was not detected in any of the controls. (P = 0.002). The distribution of HCMV gB genotypes in 12 CMV-positive UC patients was as follow: gB1, 11 (91.7%) and gB3, 1 (8.3%). The most prevalent genotype in CMV-positive UC patients was gB1.

Conclusions:

In this study, high prevalence of 91.7% HCMV gB1 genotype was predominant among HCMV-positive UC patients, which suggests that there might be an association between HCMV gB genotype 1 and UC disease.

Glycoprotein B genotyping of human cytomegalovirus strains isolated from Brazilian patients with sickle cell disease and beta-thalassemia major

The role of the human cytomegalovirus (HCMV) infection in individuals with hemoglobinopathies is unclear. Our objective was to examine the molecular and genotypic characteristics of HCMV in patients with sickle cell disease, beta-thalassemia major, and volunteer blood donors by viral load quantitation, glycoprotein B (gB) genotyping, and phylogenetic analysis. The patients with sickle cell disease demonstrated the highest HCMV DNA prevalence (13.8%), followed by the patients with beta-thalassemia major (7.6%), and the blood donors (3%). The infection was characterized by a low mean viral load (3.8×10(3) copies/mL), but infections with higher copy numbers were also observed. Genotype gB2 was detected in the majority of cases (90.9%), followed by genotype gB1 (9.1%). No gB3/gB4 genotype was detected. No statistical significance was observed between HCMV DNAemia/gB genotype and hematological alterations or severity of the disease. The high number of sickle cell disease patients with HCMV DNAemia could be due to their partial immune dysfunction (multiple transfusions, spleen dysfunction, hydroxyurea treatment). The extensive HCMV gB2 prevalence in patients with hemoglobinopathies is probably due to HCMV epidemiologic characteristics in the examined region, and can be important during the clinical management of these patients.

Role of human cytomegalovirus genotype polymorphisms in AIDS patients with cytomegalovirus retinitis

Although several host factors have been identified to influence the course of HCMV infection, it still remains unclear why in AIDS patients without highly active antiretroviral therapy human cytomegalovirus (HCMV) retinitis is one of the most common opportunistic infections, whereas in other immunosuppressed individuals it has a low incidence. It was suggested that HCMV glycoprotein B strains may be suitable as marker for virulence and HCMV retinitis. Moreover, UL144 ORF, a member of the TNF-α receptor superfamily, may play a crucial role in innate defences and adaptive immune response of HCMV infection. Furthermore, sequence analyses of HCMV genes UL128, UL130, and UL131A as major determinants of virus entry and replication in epithelial and other cell types were performed. To evaluate the association of sequence variability of depicted viral genes with HCMV retinitis and in vitro growth properties in retinal pigment epithelial cells (RPE) and human foreskin fibroblasts (HFF), we compared 14 HCMV isolates obtained from vitreous fluid and urine of AIDS patients with clinically proven HCMV retinitis. Isolates were analyzed by PCR cycle sequencing and phylogenetic analysis. In addition, sequences of HCMV strains AF1, U8, U11, VR1814, and its cell culture adapted derivates were included. Sequence analysis of gB yielded three genetic subtypes (gB type 1 (5 isolates), gB type 2 (12 isolates), and gB type 3 (5 Isolates)), whereas sequence analysis of UL144 showed a greater diversity (7 isolates type 1A, 2 isolates type 1C, 7 isolates type 2, and 3 isolates type 3). In contrast, the UL128, UL130, and UL131A genes of all low-passage isolates were highly conserved and showed no preferential clustering. Moreover, in HFF and RPE cells, all of our HCMV isolates replicated efficiently independently of their genetic subtype. In conclusion, beside a possible link between the gB subtype 2 and HCMV retinitis, our study found no direct evidence for a connection between UL144/UL128/UL130/UL131A genotypes and the incidence of HCMV retinitis in AIDS patients.

Evaluation of glycoprotein B genotypes and load of CMV infecting blood leukocytes on prognosis of AIDS patients

BACKGROUND

Cytomegalovirus (CMV) remains an important pathogen to immunocompromised patients even in the era of HAART. The present study aimed at evaluating the influence of CMV viral load and its gB genotypes on AIDS patients' outcome.

METHODS

Blood samples of 101 AIDS patients were collected and tested for HIV load, CD4 - cell count and opportunistic pathogens, including CMV. Semi-nested PCRs were run to detect CMV genome and in the positive samples, gB genotyping and CMV load were established using enzymatic restriction and real time PCR, respectively. All patients were clinically followed for four years.

RESULTS

In thirty patients (31%) CMV was detected and all fatal cases (n = 5) occurred in this group of patients (p = 0.007), but only two patients had CMV disease (1.9%). However, viral load was not statistically associated with any analyzed parameter. The most frequently observed CMV genotype was gB2 (45.16%) followed by gB3 (35.48%). gB2 genotype was more frequently found in patients with CD4-cell counts under 200 cells/mm³ (p = 0.0017), and almost all fatal cases (80%) had gB2 genotype.

CONCLUSIONS

Our study suggests that CMV and its polymorphisms in biologically relevant genes, such as the gB encoding ORF, may still influence the prognosis and outcome of AIDS patients. The gB2 genotype was associated to patient's bad outcome.

Distinct genotypic distribution of cytomegalovirus (CMV) envelope glycoprotein B (gB) in a Cuban cohort of patients with different CMV diseases

To investigate the association between human CMV glycoprotein B (gB) genotypes and CMV disease, we retrospectively analysed 73 biological samples from 56 Cuban patients with different CMV-related diseases using a multiplex nested PCR for detection of the reported 5 CMV gB genotypes. All 4 main genotypes 1 to 4 were found in the clinical samples while no genotype 5 was detected. Among the individuals analysed, genotype gB-2 was the most prevalent (38%) followed by gB-1 (30%) and mixed infections (16%) being mainly detected among immunosuppressed patients (7 out of 9), although there was no association between mixed infections and CMV rejection in transplant recipients. Genotype gB-4 was the least frequent (5 patients), which was almost exclusively detected in mixed infections (4 out of 5, p<0.0001). Genotype gB-1 was more frequently detected in AIDS patients (47%) although it was not statistically significant, while 68% of transplant patients showed mixed infections (p<0.05). This study represents the first report of human CMV gB genotypes in Cuban patients; however, the study is limited by the small number patients, thus making it difficult to draw firm conclusions about the distribution of CMV genotypes in Cuba. Nevertheless, this preliminary report has allowed us to identify that the main 4 CMV genotypes are present in the Cuban population, with genotypes 2 and 1 being the most frequent strains.

Economic evaluation of treatment administration strategies of ganciclovir for cytomegalovirus retinitis in HIV/AIDS patients in Thailand: a simulation study

BACKGROUND

There are many effective interventions, via various routes (intravenous [IV], oral [OR], intravitreal injection [IVT] and intraocular implantation [IMP]), for treating cytomegalovirus retinitis (CMVR) that have become available. There are large variations in treating CMVR in clinical practice in Thailand.

OBJECTIVE

To evaluate the incremental cost-effectiveness ratio (ICER) of providing (i) IVT, (ii) IV/OR and (iii) IMP ganciclovir to patients with HIV/AIDS and CMVR versus providing no treatment.

DESIGN

A simulation study for which the input parameters were derived from a systematic review of the literature, a hospital-based survey and patient interviews.

SETTING

The analysis assumed a Thai healthcare system perspective. However, the model was run using both societal and healthcare provider perspectives.

RESULTS

Our results suggest that IVT ganciclovir was cost effective and the best option for treating patients with CMVR irrespective of whether patients received antiretroviral treatment (ART). In patients receiving ART, moving from IVT to IV/OR ganciclovir was also likely to be a cost-effective option. Offering IMP ganciclovir was not likely to be cost effective. Providing treatments for patients with bilateral CMVR was more cost effective than providing treatments for those with unilateral CMVR, and offering treatments for patients receiving ART was better value for money than treating patients without ART.

CONCLUSIONS

Our models suggest that IV/OR ganciclovir should be recommended for the treatment of unilateral and bilateral CMVR for patients receiving ART in the Thai healthcare system. IVT ganciclovir may also have a role in the treatment of CMVR patients not receiving ART.

Cytomegalovirus and Epstein-Barr virus subtypes—The search for clinical significance

Cytomegalovirus (CMV) as well as Epstein Barr virus (EBV) genomes include regions which show in part substantial polymorphisms. Characterization of several polymorphic regions led to the identification of various CMV and EBV subtypes. Within the last years there have been undertaken numerous efforts to find out whether the diverse subtypes differentially contribute to clinical manifestations. However, although some associations have been described so far between a certain virus subtype and the development of individual diseases these analyses were greatly complicated by the huge genomic background of CMV and EBV, by the large variety of individual host-virus relations and by differences in the geographic or demographic subtype distribution. In addition, it was shown meanwhile that a substantial proportion of virus infections is due to mixed infections with different subtypes. In this review we will give an overview of the current knowledge concerning the clinical significance of individual CMV and EBV subtypes, defined by characterization of selected polymorphisms. In addition, we also focus on recent analyses which show that infection with mixed virus subtype populations may be disadvantageous compared to single virus subtype infections.

Cytomegalovirus disease in the era of highly active antiretroviral therapy (HAART)

Cytomegalovirus (CMV) infection was one of the most important opportunistic infections in HIV-infected patients before the introduction of highly active antiretroviral therapy (HAART), i.e. the combination of at least three antiretroviral drugs of different classes. Thereafter, life expectancy and quality of life increased dramatically with the persistent suppression of HIV viremia and a significant reduction in incidence of CMV disease. Nevertheless, evidence for a multitude of direct and indirect effects of CMV on HIV progression is accumulating. Even in the era of HAART, a considerable number of HIV-infected patients have a CD4 cell count below <100 mm(-3), which involves a high risk for CMV disease. The focus of the present review is on interpretation of test results, their predictive value for CMV disease, and guidance for the rational use of diagnostic assays in HIV-infected patients. Identification of patients at immediate risk for CMV disease may be accomplished by detection of CMV-DNA in leucocytes or plasma. Evidence is growing that CMV genotypes may be also relevant for the risk of CMV disease. Diagnosis of CMV disease requires in most instances demonstration of virus in biopsy specimen from the affected organ because presence of CMV in blood may not be causally related to symptoms observed. Clinical symptoms and patient characteristics are essential in the interpretation of laboratory test results and may guide the rational collection of clinical specimen and use of laboratory assays. As a consequence, a reliable diagnosis of CMV disease and early identification of patients at high risk for CMV disease requires an integrated interpretation of clinical and virological information.

Patterns of human cytomegalovirus infection in term placentas: a preliminary analysis

BACKGROUND

Primary maternal CMV infection is the major risk factor for symptomatic congenital infection as maternal immunity reduces the risk of transmission to the fetus. Analysis of first trimester placentas showed that virus replicates in the uterus and is transmitted to the placenta causing focal infection.

OBJECTIVES AND STUDY DESIGN

We examined 78 term placentas from uncomplicated deliveries for the presence of CMV DNA and evaluated evidence of infection by means of immunohistological and serological analysis.

RESULTS

PCR analysis of villus biopsy samples and decidua showed that CMV DNA was present in 62% of tissues. Seven placentas with neutralizing titers were further examined by immunohistology for expression of viral proteins. In placentas with high levels of CMV DNA, fetal blood vessels in the villus core contained neutrophils with viral replication proteins, and macrophages/dendritic cells with glycoprotein B (gB). Cord blood samples from 1 of 11 placentas contained CMV DNA, an indication of replication in the fetal compartment. In placentas with low levels of viral DNA, macrophage/dendritic cells in the villus core contained CMV gB. This pattern was comparable to that seen in early gestation placentas from women with strong neutralizing antibodies.

CONCLUSIONS

The results show CMV replication proteins in focal areas of the placenta, implying virus transmission to the fetal circulation. These preliminary results suggest that the incidence of asymptomatic congenital CMV infection might be higher than currently estimated.

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.

Sequence variability of the alpha-chemokine UL146 from clinical strains of human cytomegalovirus

Human cytomegalovirus (HCMV) is a ubiquitous pathogen that infects a variety of cell types in vivo. A region (referred to as UL/b') present in the Toledo strain of HCMV and low passage clinical isolates contains 22 additional genes, which are absent in the highly passaged laboratory strain AD169. One of these genes, UL146, encodes an alpha-chemokine. PCR amplification and sequencing of this gene from serial samples obtained from transplant recipients and samples from infants with suspected congenital HCMV infection, revealed that UL146 is a hypervariable gene in vivo. However, genetic changes were highly conserved in individuals and in renal transplant recipients multiple genotypes of UL146 were present. The majority of strains characterized maintained the conserved ELRCXC motif present in the Toledo strain of HCMV. These results provide further evidence that AD169 does not represent the authentic virus in vivo and although Towne and Toledo are more representative, major genetic differences still exist. Mixed populations of HCMV strains occur in vivo so cloning of these strains is essential if an authentic genotype is to be defined.

Recombinant modified vaccinia virus Ankara expressing a soluble form of glycoprotein B causes durable immunity and neutralizing antibodies against multiple strains of human cytomegalovirus

Human cytomegalovirus (CMV) is a viral pathogen that infects both genders, who remain asymptomatic unless they receive immunosuppressive drugs or acquire infections that cause reactivation of latent virus. CMV infection also causes serious birth defects following primary maternal infection during gestation. A safe and effective vaccine to limit disease in this population continues to be elusive. A well-studied antigen is glycoprotein B (gB), which is the principal target of neutralizing antibodies (NAb) towards CMV in humans and has been implicated as the viral partner in the receptor-mediated infection by CMV in a variety of cell types. Antibody-mediated virus neutralization has been proposed as a mechanism by which host immunity could modify primary infection. Towards this goal, an attenuated poxvirus, modified vaccinia virus Ankara (MVA), has been constructed to express soluble CMV gB (gB680-MVA) to induce CMV NAb. Very high levels of gB-specific CMV NAb were produced after two doses of the viral vaccine. NAb were durable within a twofold range for up to 6 months. Neutralization titers developed in immunized mice are equivalent to titers found clinically after natural infection. This viral vaccine, expressing gB derived from CMV strain AD169, induced antibodies that neutralized CMV strains of three different genotypes. Remarkably, preexisting MVA and vaccinia virus (poxvirus) immunity did not interfere with subsequent immunizations of gB680-MVA. The safety characteristics of MVA, combined with the robust immune response to CMV gB, suggest that this approach could be rapidly translated into the clinic.