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

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.

Diagnosis, gB genotype distribution and viral load of symptomatic congenitally infected CMV patients in Cuba

OBJECTIVE

Cytomegalovirus (CMV) is the leading cause of viral congenital infection. Some viral factors have been proposed to be CMV pathogenicity markers. The objective of this study was to investigate the frequency of congenital CMV infection in symptomatic patients and the possible association with the CMV glycoprotein B (gB) genotype and viral load.

STUDY DESIGN

A total of 361 newborns (NB) and 158 pregnant women (PW) with clinically suspected CMV infection were enrolled. Studied samples included urine, saliva, serum, vaginal swabs and amniotic fluid. CMV infection was diagnosed by multiplex nested PCR. CMV gB genotyping was performed on infected samples, followed by viral load determination.

RESULTS

Overall, 18.7% of the tested patients were positive for CMV infection, 19.7% of NB were congenitally infected and 16.5% of PW showed active CMV infection. gB-2 was the most prevalent genotype detected (39/97 patients). gB CMV mixed infections were detected in 12 patients. gB-2 was associated with mono-infections (P<0.01). Mixed infections showed higher levels of viral load compared with gB mono-infection (P=0.03). Hepatomegaly, splenomegaly, jaundice, sepsis-like syndrome and malformations were the most prevalent clinical findings. gB-4 was more frequently associated with sepsis-like syndrome than other gB genotypes (P=0.04, odds ratio=4.3, confidence interval: 0.9 to 21.6). The difference in medians of CMV load was statistically significant among patients presenting different clinical signs (P=0.04).

CONCLUSIONS

This study showed that CMV is a frequent cause of congenital infection in symptomatic Cuban patients. Despite gB2 being the most frequently detected, gB-4 was the only genotype associated with clinical features (sepsis-like syndrome in NB). No other associations among specific genotypes and clinical characteristics were found. Further studies are needed to clarify the role that viral load and genotype play in the outcome of congenital infection.

Differential decay kinetics of human cytomegalovirus glycoprotein B genotypes following antiviral chemotherapy

Background

The impact of different cytomegalovirus (HCMV) glycoprotein B (gB) genotypes on pathogenesis remains controversial.

Objectives

To investigate the effect of gB genotypes either as single infections or as part of multiple infections on the early kinetics of response to ganciclovir therapy.

Methods

Patients (n = 239) enrolled in a study of intravenous ganciclovir or valganciclovir for the treatment of HCMV disease were analysed by a gB genotype specific PCR to quantify the amount of each gB genotype present at initiation of therapy (baseline, day 0) and at days 3, 7, 14 and 21 post therapy.

Results and conclusions

In all gB groups (individual gB genotype infections and mixed genotype infections) there was a biphasic decline in viral load after therapy. The first phase half life (days 0–3) was ≤1 day and was followed over the next 18 days by a slower second phase decline with half lives ranging from 3.4 to 4.4 days. The 1st phase rapid decline in viral load was dependent upon gB genotype whereas the ultimate viral load reduction at day 21 was relatively insensitive to gB genotype. A strong correlation between 1st phase decline and extent of viral load reduction at day 21 was observed (r = 0.37; p = 0.002). These data imply that early reductions in HCMV load after therapy may be useful in predicting the duration of drug therapy needed to control HCMV replication.

Human cytomegalovirus: an enormous variety of strains and their possible clinical significance in the human host

Human cytomegalovirus (HCMV) does not exist as one defined virus genotype, but as a variety of different strains. Several studies have investigated the significance of specific viral genotypes for the clinical course of HCMV infection. Upon reinfection, patients may acquire additional HCMV strains, and infections with a mixture of HCMV strains appear to be quite common. The analysis of such mixed infections has become increasingly important, not only for investigating the clinical implications of mixed-genotype infections, but also for understanding the pathogenesis of subsequent reinfections with HCMV strains, and this is also of importance for HCMV vaccine development. This article summarizes the clinical implications of infection with individual HCMV genotypes and focuses on infection with mixed populations of HCMV strains.

Occurrence of human cytomegalovirus glycoprotein B genotypes in immunocompetent and immunosuppressed Taiwanese patients

OBJECTIVES

To investigate the differences of genotypic distributions among isolates between immunosuppressed and immunocompetent patients in a Taiwanese population.

METHODS

Human cytomegalovirus (HCMV) isolates from 76 patients with adequate chart data were analyzed. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to define gB genotypes which include gB1 to gB4. The clinical data of the 76 patients were retrospectively collected by chart review and classified into an immunosuppressed (n = 32) or immunocompetent (n = 44) group.

RESULTS

Among the 32 immunosuppressed patients, the most commonly identified HCMV genotypes were gB1 (27/32, 84.3%) and gB3 (4/32, 12.5%). 59.1% (26/44) of the immunocompetent patients were infected by gB1 while 38.6% (17/44) of them were infected by gB3. The frequency of gB1 infection in the immunosuppressed group was significantly higher than that in the immunocompetent group (p = 0.025). However, there was no statistically significant difference between gB1 and gB3 distributions by clinical diagnosis within each group.

CONCLUSIONS

Only gB1 and gB3 genotypes were identified in this Taiwanese population. Although there is no significant difference between clinical diagnosis and gB genotyping, gB1 infection is significantly more predominant in immunosuppressed patients.