Human cytomegalovirus prevalence and distribution of glycoprotein B, O genotypes among hospitalized children with respiratory infections in West China, 2009-2014

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.

Distribution of Human Cytomegalovirus Glycoprotein H Genotypes in Different Samples from Chinese Children

Objective This study aimed to investigate characteristics of human cytomegalovirus (HCMV) glycoprotein H (gH) genotypes in urine, throat swab, and serum from children and breast milk from children's mothers.

Methods Fresh urine samples, throat swabs, or serum samples from children and breast milk samples from children's mothers were collected for HCMV DNA detection. The positive samples of HCMV DNA were further detected by fluorescent quantitative polymerase chain reaction (PCR) with gH typing.

Results Of 1,703 HCMV DNA-positive samples, the highest proportion (83.3%, 85/102) of children aged between 21 days and 3 months was detected positive in breast milk samples (p = 0.002), and the highest proportion (70.5%, 110/156) of children aged above 3 months was detected positive in throat swab samples (p = 0.002). HCMV in throat swab specimens is mainly high copy (p < 0.0001), and low-copy HCMV is prevalent in breast specimens (p < 0.0001). Among them, 1,059 samples were identified as gH1 genotype, 530 samples were gH2, and 114 samples were coinfection (gH1/2). There had the highest gH2 rates (32.3%) and lowest gH1 (61.0%) rates in urine samples (p = 0.041), whereas the highest gH1 rates (71.6%) and lowest gH2 rates (19.6%) were found in breast milk samples (p = 0.032). Concerning age groups, patients aged between 21 days and 3 months had the highest gH1 proportion (p = 0.017), while patients aged above 3 months had the highest gH1 and gH2 HCMV coinfection proportion (p = 0.002). Among 43 pairs of maternal and child samples corresponding to positive samples, gH genotype of 35 pairs of samples was consistent with a rate of 81.4%.

Conclusion gH1 is the predominant genotype of HCMV in each kind of sample in China. However, the distribution of the HCMV gH genotype is different among different samples.

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.

Special issues related to the diagnosis and management of acquired aplastic anemia in countries with restricted resources, a report on behalf of the Eastern Mediterranean blood and marrow transplantation (EMBMT) group and severe aplastic anemia working party of the European Society for blood and marrow transplantation (SAAWP of EBMT)

Aplastic anemia is a relatively rare but potentially fatal disorder, with a reported higher incidence in developing countries in comparison to the West. There are significant variations in epidemiological as well as etiological factors of bone marrow failure syndromes in the developing countries in comparison to the developed world. Furthermore, the management of bone marrow failure syndromes in resource constraint settings has significant challenges including delayed diagnosis and referral, limited accessibility to healthcare facilities, treatment modalities as well as limitations related to patients who require allogeneic stem cell transplantation. Here we will provide a review of the available evidence related to specific issues of aplastic anemia in the developing countries and we summarize suggested recommendations from the Eastern Mediterranean blood and bone marrow transplantation (EMBMT) group and the severe aplastic anemia working party of the European Society of blood and marrow transplantation (SAAWP of EBMT) related to the diagnosis and therapeutic options in countries with restricted resources.

Epidemiological characteristics of human cytomegalovirus infection and glycoprotein H genotype in Chinese children

BACKGROUND

Human cytomegalovirus (HCMV) is a common pathogen that causes many diseases in young children. HCMV glycoprotein H (gH) genotypes may be associated with the type and severity of some diseases. In this study, systematic surveillance was conducted on the prevalence of HCMV infections and HCMV gH genotypes in children.

METHODS

Urine samples were collected from children admitted to the inpatient wards and outpatient departments between January 2015 and December 2016 in the Children's Hospital, Zhejiang University School of Medicine (Hangzhou, China), and these were tested by real-time PCR for HCMV DNA detection and HCMV gH genotyping.

RESULTS

During the study period, a total of 32,542 urine samples were collected and analyzed using real-time PCR to confirm HCMV infection, and 5286 (16.2%) cases were positive for HCMV DNA. From our results, children aged less than one year were the most susceptible population to HCMV. Based on the data obtained from gH probes combined with real-time PCR assay, 964 HCMV-positive samples were genotyped for gH. Among them, 584 (60.6%) were positive for gH1 subtype, 307 (31.8%) for gH2 subtype, and 73 (7.6%) for both gH1 and gH2 subtypes. The gH2 rate of 42.9% indicated HCMV infection was the highest subtype in the group aged ≤28 days while gH1 rate of 77% was the highest in the group aged >3 years. The highest gH2 rate (36.4%) and lowest gH1 rate (50.0%) were detected in children with HCMV viremia, whereas the highest gH1 rates (65.0%) and lowest gH2 rates (28.8%) were found in children with HCMV hepatitis.

CONCLUSION

The findings of our study show that children less than 1-year-old are the major population among HCMV-infected children. gH1 is the predominant genotype of HCMV in China, which occurs more frequently than gH2 genotype in the case of HCMV hepatitis. However, the opposite tendency is observed in HCMV viremia, where the gH2 genotype is predominant.

Salivary cytomegalovirus excretion in children in daycare centers and home care facilities in Japan

Cytomegalovirus (CMV) is the most common cause of congenital viral infection in developed countries. The incidence of in utero infection is high in pregnant women who are CMV antibody negative. An important infection route is in contact with children who attend daycare centers (DCCs). However, there are few reports on CMV excretion in children at DCCs in Japan. Saliva samples were collected twice during a 6-month interval from children attending one of two DCCs (DCC1 and DCC2 groups) and from those receiving home care (HC group). The samples were used to quantitatively evaluate CMV using real-time polymerase chain reaction and to determine glycoprotein B (gB) genotypes. The percentage of subjects who demonstrated CMV excretion in either the first or second sample collection was higher in the DCC groups than in the HC group, with incidences in the DCC1, DCC2, and HC groups of 53.4% (n = 47 of 88), 23.9% (n = 16 of 67), and 12.7% (n = 7 of 55), respectively. Compared with the DCC2 group, the DDC1 group had a higher incidence of CMV excretion and included more subjects with a high number of viral copies. In both DCC groups, the incidence of CMV excretion was highest in children younger than 3 years of age. In all three groups, the predominant genotypes were gB1 and gB3. Based on the higher incidence of CMV excretion in the DCC groups compared with the HC group, it is considered that CMV infection is acquired mainly in DCCs in children under the age of 3.

Distribution of cytomegalovirus genotypes among ulcerative colitis patients in Okinawa, Japan

BACKGROUND/AIMS

To determine the prevalence of glycoprotein B (gB), glycoprotein N (gN), and glycoprotein H (gH) genotypes of human cytomegalovirus (HCMV) superimposed on ulcerative colitis (UC) patients in Japan.

METHODS

Four archived stool samples and 7-archived extracted DNA from stool samples of 11 UC patients with positive multiplex polymerase chain reaction (PCR) results for HCMV were used UL55 gene encoding gB, UL73 gene encoding gN, and UL75 gene encoding gH were identified by PCR. Genotypes of gB and glycoprotein N were determined by sequencing.

RESULTS

Among 11 samples, 8 samples were amplified through PCR. gB, gN, and gH genotypes were successfully detected in 3 of 8 (37.5%), 4 of 8 (50%), and 8 of 8 (100%), respectively. The distribution of gB and gN genotypes analyzed through phylogenetic analysis were as follows: gB1 (2/3, 66.7%), gB3 (1/3, 33.3%), gN3a (2/4, 50%), and gN3b (2/4, 50%). Other gB genotypes (gB2 and gB4) and gN genotypes (gN1, gN2, and gN4) were not detected in this study. Out of successfully amplified 8 samples of gH genotype, gH1 and gH2 were distributed in 12.5% and 75% samples, respectively. Only 1 sample revealed mixed infection of gH genotype. The distribution of gH1 and gH2 differed significantly (1:6, P<0.05) in UC patients. The distribution of single gH genotype also revealed significant difference in UC patients who were treated with immunosuppressive drug (P<0.05).

CONCLUSIONS

In this study, gB1, gN3, and gH2 gene were determined as the most frequently observed genotypes in UC patients, which suggest that there might be an association between these genotypes of HCMV and UC.

Differences in Growth Properties among Two Human Cytomegalovirus Glycoprotein O Genotypes

Glycoprotein O (gO) of the human cytomegalovirus (HCMV) is the critical subunit of the envelope trimer gH/gL/gO as it interacts with platelet-derived growth factor alpha receptor upon fibroblast entry, and triggers gB-mediated fusion for fibroblast and epithelial cell infection. Eight genotypes (GT) of the highly polymorphic gO gene are described, yet it is unclear whether the distinct GTs differ in their function. Thus, we aimed to elucidate potential functional differences between two highly diverse gO GTs in an otherwise genomically identical HCMV strain. Therefore, resident gO GT1c sequence of strain TB40-BAC4-luc was entirely replaced by gO GT4 of strain Towne and both, GT1c and GT4 viruses, were investigated for their growth properties in fibroblasts and epithelial cells. In addition, two conserved gO cysteines involved in gH/gL/gO stabilization were mutated to serine either in GT1c (C218S and C343S) or GT4 (C216S and C336S) and their effects on cell-free infectivity were assessed. GT4 viruses displayed a significantly enhanced epithelial cell tropism and this resulted in higher virus release upon replication in epithelial cells when compared to GT1c viruses. Further, when the two cysteines were individually mutated in gO GT1c no impairment in cell-free infectivity was observed. This, however, was in sharp contrast to gO GT4, in which both of the corresponding cysteine mutations led to a substantial reduction in cell-free infectivity which was even more pronounced upon mutation of GT4-C336 than of GT4-C216. In conclusion, these findings provide evidence that the two highly diverse gO genotypes, GT1c and GT4, differ in their functional properties as revealed by their different infection capacities for epithelial cells and by their different responsiveness to mutation of strictly conserved cysteine residues. Thus, it is likely that the gO heterogeneity influences cell-free infectivity of HCMV also in vivo which may have important implications for virus host transmission.