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

Overview of Cytomegalovirus Ocular Diseases: Retinitis, Corneal Endotheliitis, and Iridocyclitis

Cytomegalovirus (CMV) infection is a significant clinical concern in newborns, immunocompromised patients with acquired immunodeficiency syndrome (AIDS), and patients undergoing immunosuppressive therapy or chemotherapy. CMV infection affects many organs, such as the lungs, digestive organs, the central nerve system, and eyes. In addition, CMV infection sometimes occurs in immunocompetent individuals. CMV ocular diseases includes retinitis, corneal endotheliitis, and iridocyclitis. CMV retinitis often develops in infected newborns and immunocompromised patients. CMV corneal endotheliitis and iridocyclitis sometimes develop in immunocompetent individuals. Systemic infections and CMV ocular diseases often require systemic treatment in addition to topical treatment.

Rapid and sensitive point-of-care diagnosis of human cytomegalovirus infection using RPA-CRISPR technology

Background

Human cytomegalovirus (HCMV) is a common herpesvirus that can cause a range of symptoms, from mild conditions such as fevers to severe illnesses like pneumonia. Early and accurate diagnosis of HCMV infection is crucial, particularly for vulnerable populations with limited medical care. However, current diagnostic methods are often expensive, time-consuming, and require skilled technicians.

Materials and methods

We developed an HCMV-RPA-CRISPR diagnosis platform for the rapid and cost-effective detection of HCMV infection. This method utilizes recombinase polymerase amplification (RPA) to amplify the HCMV target gene isothermally without the need for thermal cycling equipment. The platform integrates the CRISPR/Cas12a system, significantly enhancing specificity and sensitivity. A total of 13 clinical blood samples were tested to evaluate the platform's effectiveness and accuracy. Additionally, a lateral flow assay (LFA) and fluorescence detection were incorporated for straightforward and rapid visual interpretation of the results.

Results

The assay effectively detected concentrations as low as a single copy of the positive control plasmid per microliter in under 1 h, without requiring specialized equipment or training. In clinical sample evaluations, both the fluorescence readout and LFA exhibited 100% sensitivity and specificity, identifying four HCMV-positive and nine HCMV-negative samples.

Conclusion

The HCMV-RPA-CRISPR diagnosis platform is comparably effective to qPCR for HCMV diagnosis. Its applicability in common clinical laboratories, clinics, and point-of-care settings, particularly in resource-limited environments, makes it a valuable tool for widespread HCMV screening and diagnosis.

Human Cytomegalovirus (HCMV) Genetic Diversity, Drug Resistance Testing and Prevalence of the Resistance Mutations: A Literature Review

Human cytomegalovirus (HCMV) is a pathogen with high prevalence in the general population that is responsible for high morbidity and mortality in immunocompromised individuals and newborns, while remaining mainly asymptomatic in healthy individuals. The HCMV genome is 236,000 nucleotides long and encodes approximately 200 genes in more than 170 open reading frames, with the highest rate of genetic polymorphisms occurring in the envelope glycoproteins. HCMV infection is treated with antiviral drugs such as ganciclovir, valganciclovir, cidofovir, foscarnet, letermovir and maribavir targeting viral enzymes, DNA polymerase, kinase and the terminase complex. One of the obstacles to successful therapy is the emergence of drug resistance, which can be tested phenotypically or by genotyping using Sanger sequencing, which is a widely available but less sensitive method, or next-generation sequencing performed in samples with a lower viral load to detect minority variants, those representing approximately 1% of the population. The prevalence of drug resistance depends on the population tested, as well as the drug, and ranges from no mutations detected to up to almost 50%. A high prevalence of resistance emphasizes the importance of testing the patient whenever resistance is suspected, which requires the development of more sensitive and rapid tests while also highlighting the need for alternative therapeutic targets, strategies and the development of an effective vaccine.

Immunotherapy of cytomegalovirus infection by low-dose adoptive transfer of antiviral CD8 T cells relies on substantial post-transfer expansion of central memory cells but not effector-memory cells

Cytomegaloviruses (CMVs) are host species-specific in their replication. It is a hallmark of all CMVs that productive primary infection is controlled by concerted innate and adaptive immune responses in the immunocompetent host. As a result, the infection usually passes without overt clinical symptoms and develops into latent infection, referred to as "latency". During latency, the virus is maintained in a non-replicative state from which it can reactivate to productive infection under conditions of waning immune surveillance. In contrast, infection of an immunocompromised host causes CMV disease with viral multiple-organ histopathology resulting in organ failure. Primary or reactivated CMV infection of hematopoietic cell transplantation (HCT) recipients in a "window of risk" between therapeutic hemato-ablative leukemia therapy and immune system reconstitution remains a clinical challenge. Studies in the mouse model of experimental HCT and infection with murine CMV (mCMV), followed by clinical trials in HCT patients with human CMV (hCMV) reactivation, have revealed a protective function of virus-specific CD8 T cells upon adoptive cell transfer (AT). Memory CD8 T cells derived from latently infected hosts are a favored source for immunotherapy by AT. Strikingly low numbers of these cells were found to prevent CMV disease, suggesting either an immediate effector function of few transferred cells or a clonal expansion generating high numbers of effector cells. In the murine model, the memory population consists of resting central memory T cells (TCM), as well as of conventional effector-memory T cells (cTEM) and inflationary effector-memory T cells (iTEM). iTEM increase in numbers over time in the latently infected host, a phenomenon known as 'memory inflation' (MI). They thus appeared to be a promising source for use in immunotherapy. However, we show here that iTEM contribute little to the control of infection after AT, which relies almost entirely on superior proliferative potential of TCM.

Characterization of epitopes of human monoclonal antibodies against cytomegalovirus glycoprotein B for neutralization and antibody-dependent phagocytosis

As congenital cytomegalovirus (CMV) infections are the leading non-genetic cause of sensorineural hearing loss and significant neurological disabilities in children, the development of CMV vaccines should be given the highest public health priority. Although MF59-adjuvanted glycoprotein B (gB) vaccine (gB/MF59) is safe and immunogenic, its efficacy in terms of protection from natural infection was around 50 % in clinical trials. Although gB/MF59 induced high antibody titers, anti-gB antibodies contributed little to the neutralization of infection. Recent studies have found that non-neutralizing functions, including antibody-dependent phagocytosis of virions and virus-infected cells, are likely to play important roles in pathogenesis and vaccine design. Previously, we isolated human monoclonal antibodies (MAbs) that reacted with the trimeric form of gB ectodomain and found that preferential epitopes for neutralization were present on Domains (Doms) I and II of gB, while there were abundant non-neutralizing antibodies targeting Dom IV. In this study, we analyzed the phagocytosis activities of these MAbs and found the following: 1) MAbs effective for phagocytosis of the virions targeted Doms I and II, 2) the MAbs effective for phagocytosis of the virions and those of virus-infected cells were generally distinct, and 3) the antibody-dependent phagocytosis showed little correlation with neutralizing activities. Taking account of the frequency and levels of neutralization and phagocytosis, incorporation of the epitopes on Doms I and II into developing vaccines is considered desirable for the prevention of viremia.

NGS Technology in Monitoring the Genetic Diversity of Cytomegalovirus Strains

Modern molecular genetic methods, massive parallel sequencing in particular, allow for genotyping of various pathogens with the aim of their epidemiological marking and improvement of molecular epidemiological surveillance of actual infections, including cytomegalovirus infection. The aim of the study is to evaluate the next-generation sequencing (NGS) technology for genotyping clinical isolates of cytomegalovirus (CMV).

Materials and Methods

The object of the study were samples of biological substrates (leukocyte mass, saliva, urine) taken from patients who underwent liver and kidney transplantation. Detection of CMV DNA was carried out by a real-time PCR using commercial diagnostic AmpliSense CMV-FL test systems (Central Research Institute for Epidemiology, Moscow, Russia). DNA extraction was performed using DNA-sorb AM and DNA-sorb V kits (Central Research Institute for Epidemiology) in accordance with manufacturer's manual. The quality of the prepared DNA library for sequencing was assessed by means of the QIAxcel Advanced System capillary gel electrophoresis system (QIAGEN, Germany). Alignment and assembly of nucleotide sequences were carried out using CLC Genomics Workbench 5.5 software (CLC bio, USA). The sequencing results were analyzed using BLAST of NCBI server.

Results

CMV DNA samples were selected for genotyping. The two variable genes, UL55(gB) and UL73(gN), were used for CMV genotype determination, which was performed using NGS technology MiSeq sequencer (Illumina, USA). Based on the exploratory studies and analysis of literature sources, primers for genotyping on the UL55(gB) and UL73(gN) genes have been selected and the optimal conditions for the PCR reaction have been defined. The results of sequencing the UL55(gB) and UL73(gN) gene fragments of CMV clinical isolates from recipients of solid organs made it possible to determine the virus genotypes, among which gB2, gN4c, and gN4b were dominant. In some cases, association of two and three CMV genotypes has been revealed.

Conclusion

The application of the NGS technology for genotyping cytomegalovirus strains can become one of the main methods of CMV infection molecular epidemiology, as it allows for obtaining reliable results with a significant reduction in research time.

Distribution of CMV envelope glycoprotein B, H and N genotypes in infants with congenital cytomegalovirus symptomatic infection

Background

Cytomegalovirus (CMV) is the leading cause of congenital infections worldwide and contributes to long-term sequelae in neonates and children. CMV envelope glycoproteins play a vital role in virus entry and cell fusion. The association between CMV polymorphisms and clinical outcomes remains controversial. The present study aims to demonstrate the distribution of glycoprotein B (gB), H (gH) and N (gN) genotypes in congenitally CMV (cCMV) infected symptomatic infants and attempts to figure out the association between viral glycoprotein genotypes and clinical outcomes.

Methods

Genotyping of gB, gH and gN was performed in 42 cCMV symptomatic infants and 149 infants with postnatal CMV (pCMV) infection in Children's hospital of Fudan university. Nested PCR, gene sequencing and phylogenetic analyses were used to identify the genotypes.

Results

Our study demonstrated that: 1. The CMV gB1, gH1 and gN1 were the predominant genotypes among symptomatic cCMV infected infants, while gB1, gH1 and gN3a were more prevalent in pCMV group. gH1 genotype has a significant association with symptomatic cCMV infection (p = 0.006). 2. No significant correlation was found between CMV genotypes and hearing impairment. However, gH1 was more prevalent among cCMV infected infants with moderate/severe hearing loss although without statistical difference (p = 0.130). 3. gB3 was more prevalent among infants with skin petechiae (p = 0.049) and found to be associated with an increased risk of skin petechiae (OR = 6.563). The gN4a subtype was significantly associated with chorioretinitis due to cCMV infection (p = 0.007). 4. Urine viral loads were not significantly associated with different genotypes or hearing impairment among symptomatic cCMV infected infants.

Conclusions

Our findings demonstrated the overall distribution of gB, gH and gN genotypes in infants with symptomatic cCMV infection in Shanghai for the first time. The findings in our study may suggest a possible association between gH1 genotype and early infancy hearing loss. gB3 genotype was associated with a 6.5-fold increased risk of petechiae while gN4a strongly correlated with chorioretinitis due to cCMV infection. No significant correlation was found between urine viral loads and CMV genotypes or hearing impairment in cCMV infected infants.

Prognosis of Human Cytomegalovirus in Cancer Patients Undergoing Chemotherapeutic Treatment in Egypt and an Emergent Prevalence of Glycoprotein B-5

The human cytomegalovirus (HCMV) is a global opportunistic β-herpes virus causing severe diseases in immune-compromised patients, such as malignant tumor patients, especially those undergoing chemotherapeutic treatment. This study aimed to determine the prevalence of HCMV-DNA in chemotherapeutic treatment naive cancer patients, and after chemotherapy, to compare between conventional nested PCR and ELISA techniques for the detection of HCMV, and to detect glycoprotein B genotypes. Plasma and serum samples before and after three chemotherapy cycles were collected from 49 chemotherapy-naive cancer patients. DNA was extracted from plasma samples using QIAamp® DNA Mini kit. HCMV-DNA was detected using a nested PCR technique. Multiplex nested PCR was used for HCMV-glycoprotein B (gB) genotyping. HCMV-IgG and -IgM were detected using ELISA technique. Thirty one (63.3 %) of the 49 plasma samples of the chemotherapy-naïve cancer patients were positive for HCMV-DNA; 21 of which remained positive after chemotherapy. However, 18 samples were negative of which 16 became positive after chemotherapy. gB-5 was the most common glycoprotein genotype detected (80.6 %), followed by gB-1, gB-3, gB-4, and gB-2. HCMV IgG was detected in the 49 serum samples of chemotherapy-naïve patients, and after exposure to chemotherapy. HCMV-DNA is commonly identified in cancer patients. Its detection after chemotherapy exposure may suggest HCMV reactivation. The most common genotype detected in cancer patients in Egypt is gB-5 in contrast to earlier research. IgG was detected in all patients. This indicates that HCMV is endemic in Egypt, necessitating the development of public awareness campaigns about HCMV infection and preventive strategies.

Genome-wide identification and characterization of microsatellite markers within the Avipoxviruses

Microsatellite markers or Simple Sequence Repeats (SSRs) are gaining importance for molecular characterization of the virus as well as estimation of evolution patterns due to its high-polymorphic nature. The Avipoxvirus is the causative agent of pox-like lesions in more than 300 birds and one of the major diseases for the extinction of endangered avian species. Therefore, we conducted a genome-wide analysis to decipher the type, distribution pattern of 14 complete genomes derived from the Avipoxvirus genus. The in-silico screening deciphered the existence of 917-2632 SSRs per strain. In the case of compound SSRs (cSSRs), the value was obtained 44-255 per genome. Our analysis indicates that the di-nucleotide repeats (52.74%) are the most abundant, followed by the mononucleotides (34.79), trinucleotides (11.57%), tetranucleotides (0.64%), pentanucleotides (0.12%) and hexanucleotides (0.15%) repeats. The specific parameters like Relative Abundance (RA) and Relative Density (RD) of microsatellites ranged within 5.5-8.12 and 33.08-53.58 bp/kb. The analysis of RA and RD value of compound microsatellites resulted between 0.25-0.82 and 4.64-15.12 bp/kb. The analysis of motif composition of cSSR revealed that most of the compound microsatellites were made up of two microsatellites, with some unique duplicated pattern of the motif like, (TA)-x-(TA), (TCA)-x-(TCA), etc. and self-complementary motifs, such as (TA)-x-(AT). Finally, we validated forty sets of compound microsatellite markers through an in-vitro approach utilizing clinical specimens and mapping the sequencing products with the database through comparative genomics approaches.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03169-4.

Engineering, decoding and systems-level characterization of chimpanzee cytomegalovirus

The chimpanzee cytomegalovirus (CCMV) is the closest relative of human CMV (HCMV). Because of the high conservation between these two species and the ability of human cells to fully support CCMV replication, CCMV holds great potential as a model system for HCMV. To make the CCMV genome available for precise and rapid gene manipulation techniques, we captured the genomic DNA of CCMV strain Heberling as a bacterial artificial chromosome (BAC). Selected BAC clones were reconstituted to infectious viruses, growing to similar high titers as parental CCMV. DNA sequencing confirmed the integrity of our clones and led to the identification of two polymorphic loci and a deletion-prone region within the CCMV genome. To re-evaluate the CCMV coding potential, we analyzed the viral transcriptome and proteome and identified several novel ORFs, splice variants, and regulatory RNAs. We further characterized the dynamics of CCMV gene expression and found that viral proteins cluster into five distinct temporal classes. In addition, our datasets revealed that the host response to CCMV infection and the de-regulation of cellular pathways are in line with known hallmarks of HCMV infection. In a first functional experiment, we investigated a proposed frameshift mutation in UL128 that was suspected to restrict CCMV's cell tropism. In fact, repair of this frameshift re-established productive CCMV infection in endothelial and epithelial cells, expanding the options of CCMV as an infection model. Thus, BAC-cloned CCMV can serve as a powerful tool for systematic approaches in comparative functional genomics, exploiting the close phylogenetic relationship between CCMV and HCMV.

GRACy: A tool for analysing human cytomegalovirus sequence data

Modern DNA sequencing has instituted a new era in human cytomegalovirus (HCMV) genomics. A key development has been the ability to determine the genome sequences of HCMV strains directly from clinical material. This involves the application of complex and often non-standardized bioinformatics approaches to analysing data of variable quality in a process that requires substantial manual intervention. To relieve this bottleneck, we have developed GRACy (Genome Reconstruction and Annotation of Cytomegalovirus), an easy-to-use toolkit for analysing HCMV sequence data. GRACy automates and integrates modules for read filtering, genotyping, genome assembly, genome annotation, variant analysis, and data submission. These modules were tested extensively on simulated and experimental data and outperformed generic approaches. GRACy is written in Python and is embedded in a graphical user interface with all required dependencies installed by a single command. It runs on the Linux operating system and is designed to allow the future implementation of a cross-platform version. GRACy is distributed under a GPL 3.0 license and is freely available at https://bioinformatics.cvr.ac.uk/software/ with the manual and a test dataset.

Human cytomegalovirus envelope glycoprotein B, H, and N polymorphisms among infants of Shanghai area in China

Human cytomegalovirus (HCMV) is the leading cause of congenital infection and an opportunistic pathogen capable of establishing lifelong latency. In the present study, we aimed to investigate the distribution of glycoprotein B, H, and N in infants of Shanghai and correlate the genotype with active and latent HCMV infection. A total of 129 urine samples were collected between August 2014 and December 2015 from infants under 3 years with HCMV infection. Nested PCR was used to amplify the regions of UL55 (gB), UL75 (gH), and UL73 (gN). Gene sequencing and phylogenetic analyses were used to classify the genotypes. Overall, regarding gB, gB1 (57.27%) was predominant, followed by gB3 (41.82%) and gB4 (0.91%). gH1 (54.33%) was the most prevalent genotype of gH, followed by gH2 (45.67%). Concerning gN, we detected gN1 (17.44%), gN2 (2.33%), gN3a (29.07%), gN3b (8.14%), gN4a (13.95%), gN4b (15.12%), and gN4c (13.95%), among which gN3a was the dominant genotype. All the expected genotypes were present except gB2 in children with active infection: gB1 (56.25%), gB3 (42.5%), gB4 (1.25%), gH1 (58.70%), gH2 (41.30%), gN1 (19.05%), gN2 (3.17%), gN3a (25.40%), gN3b (6.35%), gN4a (15.87%), gN4b (17.46%), and gN4c (12.70%). However, among latent cases, we detected gB1 (60%), gB3 (40%), gH1 (42.86%), gH2 (57.14%), gN1 (13.04%), gN3a (39.13%), gN3b (13.04%), gN4a (8.70%), gN4b (8.70%), and gN4c (17.39%), respectively. gB2, gB4, and gN2 were absent in this group. The results revealed that gB1, gH1, and gN3a were predominant in the infants of Shanghai. gH showed different trends among children with active and latent infection.

Evolution and Genetic Diversity of Primate Cytomegaloviruses

Cytomegaloviruses (CMVs) infect many mammals, including humans and non-human primates (NHPs). Human cytomegalovirus (HCMV) is an important opportunistic pathogen among immunocompromised patients and represents the most common infectious cause of birth defects. HCMV possesses a large genome and very high genetic diversity. NHP-infecting CMVs share with HCMV a similar genomic organization and coding content, as well as the course of viral infection. Recent technological advances have allowed the sequencing of several HCMV strains from clinical samples and provided insight into the diversity of NHP-infecting CMVs. The emerging picture indicates that, with the exclusion of core genes (genes that have orthologs in all herpesviruses), CMV genomes are relatively plastic and diverse in terms of gene content, both at the inter- and at the intra-species level. Such variability most likely underlies the strict species-specificity of these viruses, as well as their ability to persist lifelong and with relatively little damage to their hosts. However, core genes, despite their strong conservation, also represented a target of adaptive evolution and subtle changes in their coding sequence contributed to CMV adaptation to different hosts. Indubitably, important knowledge gaps remain, the most relevant of which concerns the role of viral genetics in HCMV-associated human disease.

Classification of human Herpesviridae proteins using Domain-architecture Aware Inference of Orthologs (DAIO)

We developed a computational approach called Domain-architecture Aware Inference of Orthologs (DAIO) for the analysis of protein orthology by combining phylogenetic and protein domain-architecture information. Using DAIO, we performed a systematic study of the proteomes of all human Herpesviridae species to define Strict Ortholog Groups (SOGs). In addition to assessing the taxonomic distribution for each protein based on sequence similarity, we performed a protein domain-architecture analysis for every protein family and computationally inferred gene duplication events. While many herpesvirus proteins have evolved without any detectable gene duplications or domain rearrangements, numerous herpesvirus protein families do exhibit complex evolutionary histories. Some proteins acquired additional domains (e.g., DNA polymerase), whereas others show a combination of domain acquisition and gene duplication (e.g., betaherpesvirus US22 family), with possible functional implications. This novel classification system of SOGs for human Herpesviridae proteins is available through the Virus Pathogen Resource (ViPR, www.viprbrc.org).

Detection of glycoproteins B and H genotypes to predict the development of Cytomegalovirus disease in solid organ transplant recipients

BACKGROUND

Our study focuses on the role that human Cytomegalovirus (CMV) genotypes play in the development of disease.

OBJECTIVES

(1) To analyze the frequency of various genotype envelope proteins (gB, gH) in a group of solid organ transplant (SOT) recipients; (2) to assess their correlation with CMV disease; (3) to study the association between any of the genotypes and viral loads.

STUDY DESIGN

A retrospective observational study conducted by analyzing CMV gB and gH genotypes detected with real-time polymerase chain reaction (PCR)-specific assays in 162 CMV-positive blood samples from 62 SOT recipients. Demographic, clinical, and microbiological data were recorded.

RESULTS

Mixed gB genotypes were associated with viral syndrome (70%, p =  .004), earlier presentation of symptoms (48.27 ± 27.03 versus 74.33 ± 47.25 days, respectively, p =  .001), and higher median of the plasma viral load log₁₀ (UI/ml) than infection with a single genotype (p =  .004). Furthermore, the gB3 genotype was detected more frequently in patients who presented with asymptomatic viremia (77.27%, p <  .0001). The gH1 genotype was more frequent (65%) in patients who presented with asymptomatic viremia (p =  .003), and it caused infection later than gH2 or the mixed genotype (84.88 ± 48.10 versus 57.91 ± 39.18 days, respectively, p <  .001).

CONCLUSIONS

Patients who presented mixed gB genotypes more frequently developed clinical manifestations and earlier, higher, plasma viral loads. The detection of gB and gH genotypes by real-time PCR can provide relevant information to stratify the risk of SOT recipients to develop symptomatic infection by CMV.

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.

The impact of virus population diversity on the dynamics of cytomegalovirus DNAemia in allogeneic stem cell transplant recipients

Mixed cytomegalovirus (CMV) infections are associated with delayed viral clearance in solid organ transplant recipients. We investigated whether this could be extrapolated to allogeneic stem cell transplant (allo-SCT) recipients. A total of 48 plasma specimens, obtained during 29 episodes of active CMV infection in 25 non-consecutive allo-SCT patients, were analysed. Baseline blood specimens, drawn shortly prior to the inception of pre-emptive antiviral therapy (pre-treatment specimen; n=29), as well as follow-up samples obtained either after the initiation of antiviral therapy (post-treatment specimen; n=15) or during recurrent episodes (n=4) were analysed. Plasma CMV DNA loads were quantified by real-time PCR and the CMV genotyping was performed by ultra-deep sequencing of hypervariable regions in the genes coding for glycoproteins N (gN) and O (gO). A trend towards higher CMV DNA peak loads, longer CMV DNAemia episode durations and slower CMV DNAemia decay rates was observed for episodes with mixed CMV genotype populations compared to those caused by single CMV variants, although the differences did not reach statistical significance. The length of the treatment course required to clear DNAemia was significantly longer in these mixed episodes (P=0.002). Significant changes in the number or frequency of CMV gN or gO genetic variants were documented following the initiation of antiviral therapy or in recurrent episodes. CMV diversity may have a major impact on the kinetics of CMV DNAemia clearance during the treatment of active CMV infection episodes in allo-SCT recipients.

Positively Selected Sites at HCMV gB Furin Processing Region and Their Effects in Cleavage Efficiency

Human cytomegalovirus is a ubiquitous infectious agent that affects mainly immunosuppressed, fetuses, and newborns. The virus has several polymorphic regions, in particular in the envelope glycoproteins. The UL55 gene encodes the glycoprotein B that has a variable region, containing a furin cleavage site and according to the variability different genotypes are characterized. Here we investigated variability and existence of selective pressure on the UL55 variable region containing the furin cleavage site in 213 clinical sequences from patients worldwide. We showed the occurrence of positive selective pressure on gB codons 461 and 462, near the furin cleavage site. Cleavage analysis of synthesized peptides demonstrated that most mutations confer better cleavage by furin, suggesting that evolution is acting in order to increase the efficiency cleavage and supporting the hypothesis that gB processing is important in the host. We also demonstrated that peptides containing sequences, that characterize genotypes gB2 and 3, are differentially cleaved by furin. Our data demonstrate for the first time that variability in the cleavage site is related to degree of gB processing by furin.

Human cytomegalovirus glycoprotein polymorphisms and increasing viral load in AIDS patients

BACKGROUND

Multiple strains infection of human cytomegalovirus (HCMV) was found to be correlated with increased viral load in immunodeficient patients. However, the pathogenic mechanism underlying this correlation remains unclear. To evaluate genetic polymorphisms of HCMV glycoprotein and their potential role in its viral load, HCMV glycoprotein B, N, and O (gB, gN and gO) genotypes was studied in the population of HCMV infected acquired immune deficiency syndrome (AIDS) patients. The association between glycoprotein polymorphisms and HCMV viral load was analyzed.

METHODS

The genetic polymorphisms of glycoprotein from sera of 60 HCMV infected AIDS patients was investigated by multiplex nested PCR and sequencing. HCMV viral load was evaluated by quantitative PCR.

RESULTS

gB1, gO1a, and gN4a were the predominant glycoprotein genotypes in HCMV infected AIDS patients and composed 86.96%, 78.8%, and 49.2%, respectively. Only gN4a genotype infection significantly increased viral load (P = 0.048). 71% (43/60) of HCMV infected AIDS patients were found to carry multiple HCMV strains infection. A novel potential linkage of gO1a/gN4a was identified from multiple HCMV infected patients. It was the most frequent occurrence, accounted for 51.5% in 33 patients with gO and gN genotypes infection. Furthermore, the gO1a/gN4a linkage was correlated to an increased viral load (P = 0.020).

CONCLUSION

The gN4a correlates to higher level HCMV load in AIDS patients. Interestingly, a novel gO1a/gN4a linkage is identified from the patients with multiple HCMV strains infection and is also associated with an increased viral load. Therefore, the pathogenic mechanism underlying glycoprotein polymorphisms and interaction of variants should be analyzed further.

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.

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

OBJECTIVES

Human cytomegalovirus (HCMV) is an important pathogen causing morbidity and mortality in children. HCMV prevalence in children with respiratory infections has not been investigated in West China. Previous studies have suggested that glycoproteins genotypes may be associated with different clinical presentations, but the associations were controversial. The aim of this study was to determine the prevalence of HCMV infection in children with respiratory infections, the distributions of gB, gO genotypes among these isolates and their potential predictive roles for the development of symptoms in children.

METHODS

A total of 1709 respiratory specimens were obtained from hospitalised children with respiratory symptoms from 2009 to 2014 for the confirmation of HCMV infection. Glycoprotein B,O genotyping was carried out by multiplex nested PCR and sequencing.

RESULTS

The overall infection rate was 10.8%, and dominant genotypes were gB1 (74.2%) and gO1 (37.1%). Clinical characteristics differed between infants and children >1 year of age. Infants infected with HCMV had a higher frequency of fever (P < 0.001), cough (P < 0.001), rhinorrhea (P < 0.001), expectoration (P = 0.001) and diarrhoea (P = 0.005). Children <1 year age infected with gB1 had a higher rate of cough (P = 0.0192).

CONCLUSIONS

Infants infected with HCMV had a severe clinical outcome. gB1 may negatively associate with clinical presentations and quality of life in these children. The prevalence of HCMV infection and genotype distribution emphasises the importance of HCMV screening, vaccination and control for transmission.

Prospects of a vaccine for the prevention of congenital cytomegalovirus disease

Congenital human cytomegalovirus (HCMV) infection is one leading cause of childhood disabilities. Prevention of congenital HCMV disease by vaccination has consequently been identified as a priority public healthcare goal. Several vaccine candidates have been introduced in the past that aimed at the prevention of primary HCMV infection in pregnancy. None of these has provided complete protection, and no licensed vaccine is thus far available. An additional level of complexity has been reached by recent studies indicating that the burden of HCMV transmission and disease following non-primary infections in pregnancy may be higher than previously anticipated. Substantial progress in our understanding of the immunobiology of HCMV infection in pregnancy has fostered studies to test revised or novel vaccine strategies. Preventing HCMV transmission has been identified a surrogate endpoint, rendering the conduction of vaccine studies feasible with reasonable effort. Identification of the glycoprotein complex gH/gL/UL128-131 as a mediator of HCMV host cell tropism and evaluation of that complex as a major target of the neutralizing antibody response made manufacturers consider vaccine candidates that include these proteins. Detailed structural analyses of the neutralizing determinants on HCMV glycoprotein B (gB) have revived interest in using this protein in its pre-fusion conformation for vaccine purposes. Studies in pregnant women and in animal models have provided evidence that addressing the T lymphocyte response by vaccination may be crucial to prevent HCMV transmission to the offspring. CD4 T lymphocytes may be of particular importance in this respect. A simultaneous targeting of both the humoral and cellular immune response against HCMV by vaccination thus appears warranted in order to prevent congenital HCMV infection. There is, however, still need for further research to be able to define an immunological correlate of protection against HCMV transmission during pregnancy. This brief review will highlight recent developments in our understanding of the natural history and immunobiology of HCMV infection in pregnancy and their possible impact on the strategies for the development of an HCMV vaccine.

Islands of linkage in an ocean of pervasive recombination reveals two-speed evolution of human cytomegalovirus genomes

Human cytomegalovirus (HCMV) infects most of the population worldwide, persisting throughout the host's life in a latent state with periodic episodes of reactivation. While typically asymptomatic, HCMV can cause fatal disease among congenitally infected infants and immunocompromised patients. These clinical issues are compounded by the emergence of antiviral resistance and the absence of an effective vaccine, the development of which is likely complicated by the numerous immune evasins encoded by HCMV to counter the host's adaptive immune responses, a feature that facilitates frequent super-infections. Understanding the evolutionary dynamics of HCMV is essential for the development of effective new drugs and vaccines. By comparing viral genomes from uncultivated or low-passaged clinical samples of diverse origins, we observe evidence of frequent homologous recombination events, both recent and ancient, and no structure of HCMV genetic diversity at the whole-genome scale. Analysis of individual gene-scale loci reveals a striking dichotomy: while most of the genome is highly conserved, recombines essentially freely and has evolved under purifying selection, 21 genes display extreme diversity, structured into distinct genotypes that do not recombine with each other. Most of these hyper-variable genes encode glycoproteins involved in cell entry or escape of host immunity. Evidence that half of them have diverged through episodes of intense positive selection suggests that rapid evolution of hyper-variable loci is likely driven by interactions with host immunity. It appears that this process is enabled by recombination unlinking hyper-variable loci from strongly constrained neighboring sites. It is conceivable that viral mechanisms facilitating super-infection have evolved to promote recombination between diverged genotypes, allowing the virus to continuously diversify at key loci to escape immune detection, while maintaining a genome optimally adapted to its asymptomatic infectious lifecycle.

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 Genotype Distribution Among Congenitally and Postnatally Infected Patients: Association of Particular Glycoprotein (g)B and gN Types With Symptomatic Disease

Background. Human cytomegalovirus is a leading cause of congenital infection, and there are limited data on prognosis markers in disease development. We aimed to study 3 virology targets (glycoprotein [g]B, gN, and UL144) to assess their correlation with congenital infection and various organ system involvement.

Methods. Forty-eight congenital cases and 58 postnatally infected children were included (2003–2014). Genotyping for the 3 targets and distribution among the cohorts were investigated, and the relationship between the gB, gN, and UL144 types with clinical manifestations in congenital infection was also studied.

Results. All of the genotypes were similarly represented among cohorts, and the most prevalent were the UL144B, gB1, and gN1 genotypes. The gB2 genotype was associated with abnormal image findings by ultrasound and/or magnetic resonance in congenital infection (odds ratio [OR], 6.2; 95% confidence interval [CI], 1.1–34.3; P = .036); the gN1 genotype was associated with an elevated risk of developing neurological disorders (OR, 7.0; 95% CI, 1.1–45.9; P = .043). Both gN1 and gB2 were independent factors for symptomatic infection. Statistical analyses showed no association between any UL144 genotype and disease severity.

Conclusions. All of the genotypes can be involved in congenital infection, although the gB2 and gN1 genotypes might be associated with a more serious illness.

Genetic identification of cytomegaloviruses in a rural population of Côte d'Ivoire

Background

Cytomegaloviruses (CMVs) are herpesviruses that infect many mammalian species, including humans. Infection generally passes undetected, but the virus can cause serious disease in individuals with impaired immune function. Human CMV (HCMV) is circulating with high seroprevalence (60–100 %) on all continents. However, little information is available on HCMV genoprevalence and genetic diversity in subsaharan Africa, especially in rural areas of West Africa that are at high risk of human-to-human HCMV transmission. In addition, there is a potential for zoonotic spillover of pathogens through bushmeat hunting and handling in these areas as shown for various retroviruses. Although HCMV and nonhuman CMVs are regarded as species-specific, potential human infection with CMVs of non-human primate (NHP) origin, shown to circulate in the local NHP population, has not been studied.

Findings

Analysis of 657 human oral swabs and fecal samples collected from 518 individuals living in 8 villages of Côte d’Ivoire with generic PCR for identification of human and NHP CMVs revealed shedding of HCMV in 2.5 % of the individuals. Determination of glycoprotein B sequences showed identity with strains Towne, AD169 and Toledo, respectively. NHP CMV sequences were not detected.

Conclusions

HCMV is actively circulating in a proportion of the rural Côte d’Ivoire human population with circulating strains being closely related to those previously identified in non-African countries. The lack of NHP CMVs in human populations in an environment conducive to cross-species infection supports zoonotic transmission of CMVs to humans being at most a rare event.

Epigenetic regulation of human cytomegalovirus latency: an update

Human cytomegalovirus (HCMV) is a ubiquitous virus which infects 50-90% of the population worldwide. In immunocompetent hosts, HCMV either remains unnoticed or causes mild symptoms. Upon primary infection it establishes latent infection in a few cells. However, in certain situations where immunity is either immature or compromised, HCMV may reactivate and cause mortality and morbidity. Therefore, it is utmost important to understand how HCMV establishes latent infection and associated mechanisms responsible for its reactivation. Several mechanisms are involved in the regulation of latency including chromatin remodeling by an array of enzymes and microRNAs. Here we will describe the epigenetic regulation of HCMV latency. Further we will discuss the unique HCMV latency signature and patho-physiological relevance of latent HCMV infection.

High-throughput analysis of human cytomegalovirus genome diversity highlights the widespread occurrence of gene-disrupting mutations and pervasive recombination

Human cytomegalovirus is a widespread pathogen of major medical importance. It causes significant morbidity and mortality in the immunocompromised and congenital infections can result in severe disabilities or stillbirth. Development of a vaccine is prioritized, but no candidate is close to release. Although correlations of viral genetic variability with pathogenicity are suspected, knowledge about strain diversity of the 235kb genome is still limited. In this study, 96 full-length human cytomegalovirus genomes from clinical isolates were characterized, quadrupling the available information for full-genome analysis. These data provide the first high-resolution map of human cytomegalovirus interhost diversity and evolution. We show that cytomegalovirus is significantly more divergent than all other human herpesviruses and highlight hotspots of diversity in the genome. Importantly, 75% of strains are not genetically intact, but contain disruptive mutations in a diverse set of 26 genes, including immunomodulative genes UL40 and UL111A. These mutants are independent from culture passaging artifacts and circulate in natural populations. Pervasive recombination, which is linked to the widespread occurrence of multiple infections, was found throughout the genome. Recombination density was significantly higher than in other human herpesviruses and correlated with strain diversity. While the overall effects of strong purifying selection on virus evolution are apparent, evidence of diversifying selection was found in several genes encoding proteins that interact with the host immune system, including UL18, UL40, UL142 and UL147. These residues may present phylogenetic signatures of past and ongoing virus-host interactions.

IMPORTANCE

Human cytomegalovirus has the largest genome of all viruses that infect humans. Currently, there is a great interest in establishing associations between genetic variants and strain pathogenicity of this herpesvirus. Since the number of publicly available full-genome sequences is limited, knowledge about strain diversity is highly fragmented and biased towards a small set of loci. Combined with our previous work, we have now contributed 101 complete genome sequences. We have used these data to conduct the first high-resolution analysis of interhost genome diversity, providing an unbiased and comprehensive overview of cytomegalovirus variability. These data are of major value to the development of novel antivirals and a vaccine and to identify potential targets for genotype-phenotype experiments. Furthermore, they have enabled a thorough study of the evolutionary processes that have shaped cytomegalovirus diversity.

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.

Toxic megacolon and human Cytomegalovirus in a series of severe ulcerative colitis patients

BACKGROUND

Human Cytomegalovirus (HCMV) infection has been reported to be a cause of refractory ulcerative colitis (UC). Toxic megacolon (TM) is a rare but severe complication of an acute attack of UC.

OBJECTIVES

Aim of this study is to evaluate in a case-control study the association between HCMV and TM.

STUDY DESIGN

All patients who were admitted at Medicine Department of V. Cervello Hospital in Palermo (tertiary referral center) for a severe UC flare-up complicated by the onset of TM (diameter of the transverse colon>6 cm) between January 1990 and November 2011 were identified through the electronic database. A total of 24 consecutive patients (16 male/8 female) with TM were identified. Each case of TM were individually matched by sex, age, extent of the underlying disease to 24 severe UC controls who did not develop TM. A further non matched control population of 48 severe UC was included. Haematoxilin and eosin stain, immunohistochemical procedure and nested polymerase chain reaction were performed to detect HCMV genes and proteins on rectal biopsies or surgical specimens. Pp65 antigenemia was performed in order to diagnose any possible systemic infection. HCMV frequency was compared between patients with and without TM during follow-up, using Fisher's Exact test.

RESULTS AND CONCLUSIONS

HCMV was detected in histological specimens of 11 patients (46%) with TM compared to 2 (9%) severe UC matched controls (P = 0.0078) and 7 (14%) unmatched controls (p = 0,003). In severe colitis the presence of HCMV is more frequently associated with TM.

Prevalence of human cytomegalovirus, polyomaviruses, and oncogenic viruses in glioblastoma among Japanese subjects

Background

The association between human cytomegalovirus (HCMV) and glioblastoma multiforme (GBM) is becoming a new concept. However, information on the geographic variability of HCMV prevalence in GBM remains scarce. Moreover, the potential roles of various viruses, such as polyomaviruses and oncogenic viruses, in gliomagenesis remain unclear. Our aim was to investigate the prevalence of HCMV in GBM among Japanese patients. Furthermore, this was the first study that evaluated infection with four new human polyomaviruses in GBMs. This study also provided the first data on the detection of human papillomavirus (HPV) in GBM in the Eastern world.

Methods

We measured the number of various viral genomes in GBM samples from 39 Japanese patients using real-time quantitative PCR. The tested viruses included HCMV, Merkel cell polyomavirus, human polyomavirus (HPyV) 6, HPyV7, HPyV9, Epstein–Barr virus, human herpesvirus 8, and HPV. Our quantitative PCR analysis led to the detection of eight copies of the HCMV DNA mixed with DNA extracted from 10⁴ HCMV-negative cells. The presence of HCMV and HPV genomes was also assessed by nested PCR. Immunohistochemical study was also carried out to detect HPV-derived protein in GBM tissues.

Results

The viral DNAs were not detectable, with the exception of HPV, which was present in eight out of 39 (21%) GBMs. All HPV-positive cases harbored high-risk-type HPV (HPV16 and HPV18). Moreover, the HPV major capsid protein was detected in GBM tumor cells.

Conclusions

In contrast with previous reports from Caucasian patients, we did not obtain direct evidence in support of the association between HCMV and GBM. However, high-risk-type HPV infection may play a potential etiological role in gliomagenesis in a subset of patients. These findings should prompt further worldwide epidemiological studies aimed at defining the pathogenicity of virus-associated GBM.

Mck2-dependent infection of alveolar macrophages promotes replication of MCMV in nodular inflammatory foci of the neonatal lung

Infection with cytomegalovirus (CMV) shows a worldwide high prevalence with only immunocompromised individuals or newborns to become symptomatic. The host's constitution and the pathogen's virulence determine whether disease occurs after infection. Mouse CMV (MCMV) is an appreciated pathogen for in vivo investigation of host-pathogen interactions. It has recently been reported that a single base pair deletion can spontaneously occur in the open reading frame of MCMV-encoded chemokine 2 (MCK2), preventing the expression of the full-length gene product. To study the consequences of this mutation, we compared the Mck2-defective reporter virus MCMV-3D with the newly generated repaired Mck2(+) mutant MCMV-3DR. Compared with MCMV-3D, neonatal mice infected with MCMV-3DR showed severe viral disease after lung infection. Viral disease coincided with high viral activity in multiple organs and increased virus replication in previously described nodular inflammatory foci (NIF) in the lung. Notably, MCMV-3DR showed tropism for alveolar macrophages in vitro and in vivo, whereas MCMV-3D did not infect this cell type. Moreover, in vivo depletion of alveolar macrophages reduced MCMV-3DR replication in the lung. We proposed an Mck2-mediated mechanism by which MCMV exploits alveolar macrophages to increase replication upon first encounter with the host's lung mucosa.

Mixed infections with distinct cytomegalovirus glycoprotein B genotypes in Polish pregnant women, fetuses, and newborns

The purpose of this investigation was to describe a distribution of cytomegalovirus (CMV) single and multiple genotypes among infected pregnant women, their fetuses, and newborns coming from Central Poland, as well as congenital cytomegaly outcome. The study involved 278 CMV-seropositive pregnant women, of whom 192 were tested for viral DNAemia. Human cytomegalovirus (HCMV) genotyping was performed for 18 of 34 pregnant women carrying the viral DNA and for 12 of their 15 offspring with confirmed HCMV infections. Anti-HCMV antibodies levels were assessed by chemiluminescence immunoassay (CLIA) and enzyme-linked fluorescence assay (ELFA) tests. Viral DNA loads and genotypes were determined by real-time polymerase chain reaction (PCR) assays for the UL55 gene. In the pregnant women, we identified HCMV gB1, gB2, gB3, and gB4 genotypes. Single gB2, gB3, or gB4 genotypes were observed in 14 (77.8 %) women, while multiple gB1–gB2 or gB2–gB3 genotypes were observed in four (22.2 %). Maternal HCMV genotypes determined the genotypes identified in their fetuses and newborns (p ≤ 0.050). Half of them were infected with single HCMV gB1, gB2, or gB3 genotypes and the other half with multiple gB1–gB2 or gB2–gB3 genotypes. Single and multiple genotypes were observed in both asymptomatic and symptomatic congenital cytomegaly, although no gB3 genotype was identified among asymptomatic cases. In Central Poland, infections with single and multiple HCMV strains occur in pregnant women, as well as in their fetuses and neonates, with both asymptomatic and symptomatic infections. HCMV infections identified in mothers seem to be associated with the viral genotypes in their children.

Congenital cytomegalovirus infection: Clinical presentation, epidemiology, diagnosis and prevention

Cytomegalovirus is the most common congenital infection causing serious disease in infants. It is the leading infectious cause of sensorineural hearing loss and neurodevelopmental disability in developed countries. Despite the clinical importance of congenital cytomegalovirus, surveys show there is limited awareness and knowledge in the medical and general community about congenital cytomegalovirus infection. This article reviews the clinical features, global epidemiology, transmission and risk factors for cytomegalovirus infections. It also highlights several major advances made in recent years in the diagnosis and prevention of cytomegalovirus infection during pregnancy. Although research is ongoing, no therapy is currently proven to prevent or treat maternal, fetal or neonatal cytomegalovirus infection. Education of women regarding hygiene measures can help prevent cytomegalovirus infection and are currently the best strategy to prevent congenital cytomegalovirus disease.

The use of microRNA by human viruses: lessons from NK cells and HCMV infection

Depending on ethnicity and on social conditions, between 40 and 90 % of the population is infected with human cytomegalovirus (HCMV). In immunocompetent patients, the virus may cause an acute disease and then revert to a state of latency, which enables its coexistence with the human host. However, in cases of immunosuppression or in neonatal infections, HCMV can cause serious long-lasting illnesses. HCMV has developed multiple mechanisms in order to escape its elimination by the immune system, specifically by two killer cell types of the adaptive and the innate immune systems; cytotoxic T lymphocytes (CTL) and natural killer (NK) cells, respectively. Another fascinating aspect of HCMV is that like other highly developed herpesviruses, it expresses its own unique set of microRNAs. Here, we initially describe how the activity of NK cells is regulated under normal conditions and during infection. Then, we discuss what is currently known about HCMV microRNA-mediated interactions, with special emphasis on immune modulation and NK cell evasion. We further illustrate the significant modulation of cellular microRNAs during HCMV infection. Although, the full target spectrum of HCMV microRNAs is far from being completely elucidated, it can already be concluded that HCMV uses its "multitasking" microRNAs to globally affect its own life cycle, as well as important cellular and immune-related pathways.

Inflammatory breast cancer: high incidence of detection of mixed human cytomegalovirus genotypes associated with disease pathogenesis

Inflammatory breast cancer (IBC) is a highly metastatic, aggressive, and fatal form of breast cancer. Patients presenting with IBC are characterized by a high number of axillary lymph node metastases. Recently, we found that IBC carcinoma tissues contain significantly higher levels of human cytomegalovirus (HCMV) DNA compared to other breast cancer tissues that may regulate cell signaling pathways. In fact, HCMV pathogenesis and clinical outcome can be statistically associated with multiple HCMV genotypes within IBC. Thus, in the present study, we established the incidence and types of HCMV genotypes present in carcinoma tissues of infected non-IBC versus IBC patients. We also assessed the correlation between detection of mixed genotypes of HCMV and disease progression. Genotyping of HCMV in carcinoma tissues revealed that glycoprotein B (gB)-1 and glycoprotein N (gN)-1 were the most prevalent HCMV genotypes in both non-IBC and IBC patients with no significant difference between patients groups. IBC carcinoma tissues, however, showed statistically significant higher incidence of detection of the gN-3b genotype compared to non-IBC patients. The incidence of detection of mixed genotypes of gB showed that gB-1 + gB-3 was statistically significantly higher in IBC than non-IBC patients. Similarly, the incidence of detection of mixed genotypes of gN showed that gN-1 + gN-3b and gN-3 + gN-4b/c were statistically significant higher in the carcinoma tissues of IBC than non-IBC. Mixed presence of different HCMV genotypes was found to be significantly correlated with the number of metastatic lymph nodes in non-IBC but not in IBC patients. In IBC, detection of mixed HCMV different genotypes significantly correlates with lymphovascular invasion and formation of dermal lymphatic emboli, which was not found in non-IBC patients.

Cytomegalovirus alpha-chemokine genotypes are associated with clinical manifestations in children with congenital or postnatal infections

Human cytomegalovirus (HCMV) is the leading cause of congenital infections. The aim of our study was to determine the prevalence of genotypes based on the highly polymorphic UL146 and UL147 HCMV genes and the relationship between the genotype and symptoms or viral load. We analyzed samples from 121 infants with symptomatic HCMV infection, including 32 congenitally infected newborns. The G7 and G5 genotypes were predominant in postnatal infection, whereas the G1 genotype was prevalent in congenital infection. Central nervous system (CNS) damage and hepatomegaly were detected more frequently among children infected with the G1 genotype than in those infected by other genotypes. An association between the viral genotype and viruria level was found. There was a strong correlation between HCMV genotypes determined through the UL146 and UL147 sequences (ĸ=0.794). In conclusion, we found that certain vCXCL genotypes are associated with clinical sequelae following HCMV infection.

Ly49C-dependent control of MCMV Infection by NK cells is cis-regulated by MHC Class I molecules

Natural Killer (NK) cells are crucial in early resistance to murine cytomegalovirus (MCMV) infection. In B6 mice, the activating Ly49H receptor recognizes the viral m157 glycoprotein on infected cells. We previously identified a mutant strain (MCMVG1F) whose variant m157 also binds the inhibitory Ly49C receptor. Here we show that simultaneous binding of m157 to the two receptors hampers Ly49H-dependent NK cell activation as Ly49C-mediated inhibition destabilizes NK cell conjugation with their targets and prevents the cytoskeleton reorganization that precedes killing. In B6 mice, as most Ly49H+ NK cells do not co-express Ly49C, the overall NK cell response remains able to control MCMVm157G1F infection. However, in B6 Ly49C transgenic mice where all NK cells express the inhibitory receptor, MCMV infection results in altered NK cell activation associated with increased viral replication. Ly49C-mediated inhibition also regulates Ly49H-independent NK cell activation. Most interestingly, MHC class I regulates Ly49C function through cis-interactions that mask the receptor and restricts m157 binding. B6 Ly49C Tg, β2m ko mice, whose Ly49C receptors are unmasked due to MHC class I deficient expression, are highly susceptible to MCMVm157G1F and are unable to control a low-dose infection. Our study provides novel insights into the mechanisms that regulate NK cell activation during viral infection.

A method enabling high-throughput sequencing of human cytomegalovirus complete genomes from clinical isolates

Human cytomegalovirus (HCMV) is a ubiquitous virus that can cause serious sequelae in immunocompromised patients and in the developing fetus. The coding capacity of the 235 kbp genome is still incompletely understood, and there is a pressing need to characterize genomic contents in clinical isolates. In this study, a procedure for the high-throughput generation of full genome consensus sequences from clinical HCMV isolates is presented. This method relies on low number passaging of clinical isolates on human fibroblasts, followed by digestion of cellular DNA and purification of viral DNA. After multiple displacement amplification, highly pure viral DNA is generated. These extracts are suitable for high-throughput next-generation sequencing and assembly of consensus sequences. Throughout a series of validation experiments, we showed that the workflow reproducibly generated consensus sequences representative for the virus population present in the original clinical material. Additionally, the performance of 454 GS FLX and/or Illumina Genome Analyzer datasets in consensus sequence deduction was evaluated. Based on assembly performance data, the Illumina Genome Analyzer was the platform of choice in the presented workflow. Analysis of the consensus sequences derived in this study confirmed the presence of gene-disrupting mutations in clinical HCMV isolates independent from in vitro passaging. These mutations were identified in genes RL5A, UL1, UL9, UL111A and UL150. In conclusion, the presented workflow provides opportunities for high-throughput characterization of complete HCMV genomes that could deliver new insights into HCMV coding capacity and genetic determinants of viral tropism and pathogenicity.

Genomic and functional characteristics of human cytomegalovirus revealed by next-generation sequencing

The complete genome of human cytomegalovirus (HCMV) was elucidated almost 25 years ago using a traditional cloning and Sanger sequencing approach. Analysis of the genetic content of additional laboratory and clinical isolates has lead to a better, albeit still incomplete, definition of the coding potential and diversity of wild-type HCMV strains. The introduction of a new generation of massively parallel sequencing technologies, collectively called next-generation sequencing, has profoundly increased the throughput and resolution of the genomics field. These increased possibilities are already leading to a better understanding of the circulating diversity of HCMV clinical isolates. The higher resolution of next-generation sequencing provides new opportunities in the study of intrahost viral population structures. Furthermore, deep sequencing enables novel diagnostic applications for sensitive drug resistance mutation detection. RNA-seq applications have changed the picture of the HCMV transcriptome, which resulted in proof of a vast amount of splicing events and alternative transcripts. This review discusses the application of next-generation sequencing technologies, which has provided a clearer picture of the intricate nature of the HCMV genome. The continuing development and application of novel sequencing technologies will further augment our understanding of this ubiquitous, but elusive, herpesvirus.

Cytomegalovirus glycoprotein H genotype distribution and the relationship with hearing loss in children

Cytomegalovirus (CMV) is a leading cause of congenital infection and a leading infectious cause of hearing loss in children. The ORF UL75 gene encodes envelope glycoprotein H (gH), which is essential for CMV entry into host cells and the target of the immune response in humans. However, the distribution of gH variants and the relationship between the viral genotype, viral load, and sequelae in children infected with CMV is debated. The UL75 genetic variation of CMV isolates from 42 newborns infected congenitally with CMV and 93 infants with postnatal or unproven congenital CMV infection was analyzed. Genotyping was performed by analysis of PCR-amplified fragments, and the viral load was measured by quantitative real-time PCR. There were no differences in the distribution of gH genotypes in the children infected congenitally and postnatally. Mixed-genotype infections with both gH1 and gH2 variants were detected in approximately 25% of the examined patients. No relationship between UL75 gene polymorphisms and the symptoms at birth was observed. The results suggest that the infection with gH2 genotype diminishes the risk of hearing loss in children (P = 0.010). In addition, sensorineural hearing loss was associated with CMV gH1 genotype infection in infants (P = 0.032) and a high viral load in urine (P = 0.005). In conclusion, it was found that the gH genotype does not predict clinical sequelae in newborn infants following congenital CMV infection. However, these results suggest that the gH genotype might be associated with hearing loss in children.

Polymorphisms in TLR-2 are associated with congenital cytomegalovirus (CMV) infection but not with congenital CMV disease

BACKGROUND

Cytomegalovirus (CMV) is the most common cause of congenital virus infection. However, the risk factors for infection in utero and for progression to a severe clinical outcome remain uncertain. Recent studies have identified associations of specific single nucleotide polymorphisms (SNPs) in Toll-like receptor (TLR) genes with susceptibility to infections of some viruses and with their clinical outcome.

METHODS

Genetic polymorphisms in the TLR-2, TLR-4, and TLR-9 genes were analyzed in 87 children with congenital CMV infections by the TaqMan allelic discrimination assay. The frequencies of genotypes in the general Japanese population were obtained from the National Center for Biotechnology Information (NCBI) databases. Associations between the analyzed SNPs and congenital CMV infection or disease were evaluated.

RESULTS

The CC genotype at SNP rs3804100 in the TLR-2 gene was significantly associated with congenital CMV infection but not with congenital CMV disease. Furthermore, the AG genotype at SNP rs1898830 in the TLR-2 gene tended to be identified less frequently in children with congenital CMV infection. There were no statistically significant associations between SNPs in the TLR-4 and TLR-9 genes and congenital CMV infection or disease.

CONCLUSION

TLR-2 polymorphisms may have some association with congenital CMV infection, although the mechanism underlying this effect remains to be clarified.

Cytomegalovirus (CMV) genotype in allogeneic hematopoietic stem cell transplantation

Background

Based on sequence variation in the UL55 gene that encodes glycoprotein B (gB), human cytomegalovirus (CMV) can be classified into four gB genotypes. Previous studies have suggested an association between CMV gB genotype and clinical outcome in patients who underwent an allogeneic hematopoietic stem cell transplant (HSCT). The goals of this study were identify patients with active infection caused by CMV in recipients of HSCT; determine the prevalence of CMV genotypes in the study group; correlate genotype with CMV disease, acute GVHD and overall survival.

Methods

The diagnosis of active CMV infection after allogeneic HSCT was detected by antigenemia (AGM) and/or nested-PCR (N-PCR). Positive samples from patients with active CMV infection were submitted to genotyping using N-PCR to amplify a region of UL55, followed by restriction analysis based on HinfI and RsaI digestion. Real-time PCR (qPCR) was used to determine the viral load during active CMV infection and antiviral treatment.

Results

Sixty-three allogeneic HSCT recipients were prospectively evaluated; 49/63 (78%) patients were infected with CMV genotypes – gB1 19/49 (39%), gB2 17/49 (35%), gB3 3/49 (6%), gB4 7/49 (14%) – and 3 (6%) had mixed CMV genotypes (gB1 + gB3, gB1 + gB4 and gB2 + gB4). Characterized by gastrointestinal disease, CMV disease occurred in 3/49 (6.1%) patients, who had CMV gB3 genotype. These gB3 genotype patients presented an increasing AGM number, mean 125 (± 250) (P = 0.70), and qPCR copies/ml, mean 37938 (SD ± 50542) (P = 0.03), during antiviral treatment, when compared with other CMV genotypes. According to CMV genotypes, stratified overall survival was 55% for gB1, 43% for gB2; 0% for gB3 and 57% for gB4 (P = 0.03).

Conclusions

One of the restrictions of the presented study was the low number of CMV gB sub-cohorts). However, we demonstrated that the frequency of active CMV infection in this HSCT population was high, and the most prevalent genotype in these patients with active CMV infection was gB1 and gB2 genotype (74%). In Brazil, HSCT recipients seem to carry mainly gB1 and gB2 CMV genotype.

Distribution of cytomegalovirus gN variants and associated clinical sequelae in infants

BACKGROUND

Human cytomegalovirus (HCMV) is the most widespread cause of congenital infection. The effects of various viral strains and viral loads on the infection outcome have been under debate.

OBJECTIVES

To determine the distribution of gN variants in HCMV strains isolated from children with congenital or postnatal infection and to establish the relationship between the viral genotype, the viral load, and the sequelae.

STUDY DESIGN

The study population included congenitally HCMV-infected newborns and children with postnatal or unproven congenital HCMV infection. The genotyping was performed by RFLP analysis of PCR-amplified fragments, and the viral load was measured by quantitative real-time PCR.

RESULTS

Our results demonstrated that the HCMV genotypes gN3b, gN4b, and gN4c were prevalent in the patients examined. There were no differences in the distributions of gN genotypes in the congenitally and postnatally infected children. Multiple HCMV strains were detected in both groups of children. A significant association between the HCMV gN4 genotype and the incidence of neurological disorders was observed (p=0.045). Our results suggest that the detection of the gN2 or the gN4 genotype may be indicative of serious manifestations in children. In contrast, the gN3b and the gN1 genotypes represent less pathogenic HCMV strains. The HCMV load in urine was significantly higher in children with congenital infection compared with children with postnatal infection. No correlation was found between the viral load and the genotype.

CONCLUSION

Our results suggest that the gN genotype may be a virological marker of symptomatic HCMV infection in newborns.