Interstrain variations in the cytomegalovirus (CMV) glycoprotein B gene sequence among CMV-infected children attending six day care centers

Cytomegalovirus (CMV) Shedding in French Day-Care Centers: A Nationwide Study of Epidemiology, Risk Factors, Centers' Practices, and Parents' Awareness of CMV

BACKGROUND

Congenital cytomegalovirus (CMV) remains an important healthcare burden, resulting from primary or secondary infection in pregnant women. Exposure to young children's saliva is a major risk factor, as prevalence of CMV shedding can reach 34%.

METHODS

This cross-sectional, multicenter, nationwide study was conducted in randomly selected day care centers (DCCs), and complemented with a survey among parents and DCCs. All children aged >3 months were eligible. The study measured the CMV shedding prevalence in children's saliva and described CMV genotypes epidemiology. The risk factors for CMV shedding and high viral load were evaluated using multivariable models.

RESULTS

A total of 93 DCCs participated. Among the 1770 enrolled children with evaluable samples, the CMV shedding prevalence was 40% (713/1770, 95% confidence interval, 34.6-46.1), independently associated with children aged between 12 and 18 months, history of CMV infection in ≥1 parents, a mid-level income. Prevalence increased with DCC staff workload and attending children number. Viral load was ≥5 log-copies CMV/mL in 48% (342/713). Risk factors for higher viral load included children aged between 12 and 18 months, and still being breastfed. The most frequent genotype combinations were gB1-gN4c-gH2 (6.9%), gB1-gN2-gH2 (6.3%), gB4a-gN3a-gH1 (6.3%), and gB1-gN3b-gH2 (5,7%). CMV awareness was low in parents: their serological status was unknown by 72% of mothers and 82% of fathers. Only 41% knew something about CMV.

CONCLUSIONS

CMV shedding was independently associated with risk factors related to the children, family and DCC. Some of these risk factors may influence prevention strategies, including through an improved information provided to parents.

CLINICAL TRIALS REGISTRATION

NCT01704222.

On the Demographic and Selective Forces Shaping Patterns of Human Cytomegalovirus Variation within Hosts

Human cytomegalovirus (HCMV) is a member of the β -herpesvirus subfamily within Herpesviridae that is nearly ubiquitous in human populations, and infection generally results only in mild symptoms. However, symptoms can be severe in immunonaive individuals, and transplacental congenital infection of HCMV can result in serious neurological sequelae. Recent work has revealed much about the demographic and selective forces shaping the evolution of congenitally transmitted HCMV both on the level of hosts and within host compartments, providing insight into the dynamics of congenital infection, reinfection, and evolution of HCMV with important implications for the development of effective treatments and vaccines.

Human cytomegalovirus quantification in toddlers saliva from day care centers and emergency unit: a feasibility study

BACKGROUND

Cytomegalovirus (CMV) infection is the most important cause of congenital viral infection in developed countries. In utero transmission occurs at higher rates in seronegative women during primary infection, especially those in contact with young children in day-care centers (DCC). Nevertheless data on variability of CMV excretion among children in French DCCs are lacking, and are important for public health planning.

OBJECTIVES

Our main objective was to assess the feasibility of a salivary sample in DCCs in order to study CMV excretion among toddlers. Our secondary aims were to assess prevalence of CMV excretion in children attending Hospital Emergency Unit (EU) in comparison with various types of DCCs and to validate the analytical chain for collected specimens.

STUDY DESIGN

Excretion of CMV in saliva was quantified using a real-time PCR assay in children aged from 3 months to 6 years old in EU and in DCC, with gB, gH and gN genotypes determined in infected children. Salivary sampling was performed using small sponges placed into a DNA conservation medium. Socio cultural and medical information were collected from attending parents.

RESULTS

A total of 625 children were included, with 256 from six DCCs and 369 from one EU. In DCCs, the acceptability of the procedure was 87.3% (95%CI 78.5-96.2) amongst parents and children, and in the EU, acceptability was higher at 97.6% (95%CI 95.5-98.9). CMV shedding overall prevalence was 21.7% (95%CI 17.6-26.2), with CMV shedding prevalence in DCCs of 51.9% (95%CI 22.8-81.1).

CONCLUSION

We validated the feasibility and acceptability of measuring CMV shedding in the saliva of French toddlers. The discrepancy between CMV infection rates in day care centers and in the general population (as sampled in the EU) indicates the need for a further study to determine risk factors and shedding levels in the DCC population.

qPCR is a sensitive and rapid method for detection of cytomegaloviral DNA in formalin-fixed, paraffin-embedded biopsy tissue

It is crucial to identify cytomegalovirus (CMV) infection in the gastrointestinal (GI) tract of immunosuppressed patients, given their greater risk for developing severe infection. Many laboratory methods for the detection of CMV infection have been developed, including serology, viral culture, and molecular methods. Often, these methods reflect systemic involvement with CMV and do not specifically identify local tissue involvement. Therefore, detection of CMV infection in the GI tract is frequently done by traditional histology of biopsy tissue. Hematoxylin and eosin (H&E) staining in conjunction with immunohistochemistry (IHC) have remained the mainstays of examining these biopsies. H&E and IHC sometimes result in atypical (equivocal) staining patterns, making interpretation difficult. It was shown that quantitative polymerase chain reaction (qPCR) for CMV can successfully be performed on formalin-fixed, paraffin-embedded (FFPE) biopsy tissue for very high sensitivity and specificity. The goal of this protocol is to demonstrate how to perform qPCR testing for the detection of CMV in FFPE biopsy tissue in a clinical laboratory setting. This method is likely to be of great benefit for patients in cases of equivocal staining for CMV in GI biopsies.

qPCR increases sensitivity to detect cytomegalovirus in formalin-fixed, paraffin-embedded tissue of gastrointestinal biopsies

Histopathologic diagnosis of gastrointestinal (GI) tract cytomegaloviral (CMV) infection relies on hematoxylin and eosin (H&E)-stained tissue, along with the aid of immunohistochemistry (IHC). However, non-classic appearing inclusions or atypical IHC staining patterns remain an ongoing concern for pathologists. We reported the use of real-time polymerase chain reaction (qPCR) on nucleic acid extracted from paraffin-embedded, formalin-fixed tissue of GI biopsies from cases of CMV infection (n = 91) diagnosed by H&E and IHC. Seventy-nine biopsies, including normal colon biopsies (n = 35), active colitis (n = 25), and active duodenitis (n = 19), were used as negative controls. Of 91 CMV-positive biopsies diagnosed by histology, 88 tested positive by qPCR, with a sensitivity of 96.7%. Of 79 negative controls, 78 were negative and 1 positive by qPCR, resulting in a specificity of 98.7%. Of the cases that were positive for CMV by histopathology, there were an additional 40 biopsies taken from these patients either during the same or previous procedures, some taken just days prior, which were negative for CMV by histology. Interestingly, 22 (55%) of these biopsies tested positive by qPCR, which correlated well with additional clinical CMV results. By defining qPCR as the "gold standard" for a CMV result, histology (H&E and/or IHC) had a sensitivity and specificity of 79% and 97%, respectively. Eighteen biopsies were found negative by H&E and equivocal by IHC. Among them, 14 (78%) tested positive for CMV by qPCR, which also correlated well with additional clinical results. qPCR is a sensitive, specific, and rapid molecular tool that may be helpful to aid in early diagnosis of CMV infection on equivocal or clinically highly suspicious small GI biopsies.

Review of cytomegalovirus shedding in bodily fluids and relevance to congenital cytomegalovirus infection

Congenital cytomegalovirus (CMV) infections are a leading cause of sensorineural hearing loss (SNHL) and neurological impairment. Congenital transmission of CMV can occur with maternal primary infection, reactivation, or reinfection during pregnancy. We reviewed studies of CMV shedding in bodily fluids (defined as CMV detected by culture or CMV DNA detected by polymerase chain reaction). Following diagnosis at birth, children with congenital CMV infection exhibited the highest prevalences of CMV shedding (median = 80%, number of sample population prevalences [N] = 6) and duration of shedding, with a steep decline by age five. Healthy children attending day care shed more frequently (median = 23%, N = 24) than healthy children not attending day care (median = 12%, N = 11). Peak shedding prevalences in children occurred at 1-2 years of age, confirming that young children are the key transmission risk for pregnant women. CMV shedding among children was more prevalent in urine specimens than in oral secretions (median prevalence difference = 11.5%, N = 12). Adults with risk factors such as STD clinic attendance had higher shedding prevalences (median = 22%, N = 20) than adults without risk factors (median = 7%, N = 44). In adults with risk factors, CMV was shed more frequently in urine; in adults without risk factors genital shedding was most common. The prevalence of CMV shedding in nine sample populations of pregnant women increased with advancing gestation. In seven sample populations of children with congenital CMV infection, higher viral load at birth was consistently associated with an elevated risk of SNHL. Higher CMV viral load at birth also consistently correlated with the presence of symptoms of congenital CMV at birth. Published 2011. This article is a US Government work and is in the public domain in the USA.

Genetic variability of cytomegalovirus glycoprotein O in hematopoietic stem cell transplant recipients

Genetic variation of cytomegalovirus (CMV) strains can correlate with their pathogenicity for immunocompromised patients. Glycoprotein O (gO), together with glycoprotein L and glycoprotein H, mediate the fusion of the viral envelope with the cell membrane and promotes virus penetration, envelopment, and release. The variability of gO might play a role in CMV cell tropism. The goal was a retrospective analysis of gO variability in a cohort of hematopoietic stem cell transplant (HSCT) recipients to determine the distribution of gO genotypes and to investigate their impact on clinical outcome and manifestation of CMV infection.

METHODS

In archived blood samples from 51 adult allogeneic HSCT recipients with active CMV infection, gO was analyzed by sequencing the N-terminal domain of the UL74 gene using the dye deoxy termination method.

RESULTS

The gO1 and gO2 clades were most common (39% and 20%, respectively, and gO3 was associated with higher risk of symptomatic infection (P = 0.026 in multivariant analysis). Despite being associated with higher antigenemia levels (P = 0.02), gO4 had the best survival and lower rate of CMV recurrence. No significant differences were found in clinical manifestation and outcome of CMV disease between patients with various gO clades. Because CMV strains sharing an identical gO sequence differed in glycoprotein B genotypes, sequencing the N-terminal part of the gO gene does not seem to be optimal for the identification of strains.

CONCLUSIONS

gO genotyping may contribute to the biological characterization of CMV strains in HSCT recipients.

[Is maternal infection with cytomegalovirus prevention possible?]

Cytomegalovirus (CMV) is the most frequent cause of congenital viral infection in developed countries. Vaccines are currently under development and antiviral treatment or passive immunizations for pregnant women with CMV primary infection are about to be evaluated in randomized trials. However, as it has been shown in few studies, preventing transmission through behavioral changes could be, at the moment, the most effective and inexpensive way to decrease risk of CMV infection during pregnancy. Despite difficulties, such counseling programs deserve to be established.

Review of cytomegalovirus seroprevalence and demographic characteristics associated with infection

Cytomegalovirus establishes a lifelong latent infection following primary infection that can periodically reactivate with shedding of infectious virus. Primary infection, reactivation and reinfection during pregnancy can all lead to in utero transmission to the developing fetus. Congenital CMV infections are a major cause of permanent hearing loss and neurological impairment. In this literature review, we found that CMV infection was relatively common among women of reproductive age, with seroprevalence ranging from 45 to 100%. CMV seroprevalence tended to be highest in South America, Africa and Asia and lowest in Western Europe and United States. Within the United States, CMV seroprevalence showed substantial geographic variation as well, differing by as much as 30 percentage points between states, though differences might be explained by variation in the types of populations sampled. Worldwide, seroprevalence among non-whites tended to be 20-30 percentage points higher than that of whites (summary prevalence ratio (PR) = 1.59, 95% confidence interval (CI) = 1.57-1.61). Females generally had higher seroprevalences than males, although in most studies the differences were small (summary PR = 1.13, 95% CI = 1.11-1.14). Persons of lower socioeconomic status were more likely to be CMV seropositive (summary PR = 1.33, 95% CI = 1.32-1.35). Despite high seroprevalences in some populations, a substantial percentage of women of reproductive age are CMV seronegative and thus at risk of primary CMV infection during pregnancy. Future vaccine or educational campaigns to prevent primary infection in pregnant women may need to be tailored to suit the needs of different populations.

Active human cytomegalovirus infection and glycoprotein b genotypes in brazilian pediatric renal or hematopoietic stem cell transplantation patients

A prospective analysis of active Human Cytomegalovirus infection (HCMV) was conducted on 33 pediatric renal or hematopoietic stem cell post-transplant patients. The HCMV-DNA positive samples were evaluated for the prevalence of different gB subtypes and their subsequent correlation with clinical signs. The surveillance of HCMV active infection was based on the monitoring of antigenemia (AGM) and on a nested polymerase chain reaction (N-PCR) for the detection of HCMV in the patients studied. Using restriction analysis of the gB gene sequence by PCR-RFLP (Restriction Fragment Length Polymorphism), different HCMV strains could be detected and classified in at least four HCMV genotypes. Thirty-three pediatric recipients of renal or bone marrow transplantation were monitored. Twenty out of thirty-three (60.6%) patients demonstrated active HCMV infection. gB1 and gB2 genotypes were more frequent in this population. In this study, we observed that gB2 had correlation with reactivation of HCMV infection and that patients with mixture of genotypes did not show any symptoms of HCMV disease. Future studies has been made to confirm this.

Variability of UL18, UL40, UL111a and US3 immunomodulatory genes among human cytomegalovirus clinical isolates from renal transplant recipients

BACKGROUND

Variability of human cytomegalovirus (HCMV) genes counteracting immune responses is poorly investigated in non-cultured clinical strains.

OBJECTIVES

In HCMV-infected renal graft recipients, we aimed to (i) investigate the variability of four HCMV immunomodulatory genes, without any culture-related viral selection, (ii) provide evolutionary sequence data, and (iii) study co-existing HCMV variants and their evolution.

STUDY DESIGN

UL18, UL40, UL111a and US3 were sequenced in 31 blood samples from 17 patients (8 with sequential samples). Cloning of UL40 PCR products was performed in one donor-positive/recipient-positive (D+/R+) patient's samples.

RESULTS

Each patient harboured a unique strain (combination of four genes), however single identical genes were demonstrated among various patients, suggesting recombination events. Sequencing showed in D+/R- recipients, either complete gene stability (four patients) or significant variability (one patient); in three D+/R+ patients, multiple gene variations, possibly linked to super- or co-infections. Cloning evidenced different variants at each time point with an increasing variability over time, illustrating possibly viral reactivations and the subsequent evolution of the variants mixture.

CONCLUSION

A noticeable HCMV natural polymorphism was shown, with different evolutive patterns. Moreover, we described the co-evolution of variants mixtures in one patient. Consequences on HCMV infection and graft function deserve further studying.

Comparative sequence analysis of US28 gene of human cytomegalovirus strains isolated from HIV-positive patients

Human Cytomegalovirus (HCVM) encodes several G-protein coupled receptors, such as US28 protein. We determined the US28 gene sequence from clinical isolates obtained from 17 Human Immunodeficiency Virus (HIV)-infected patients with HCMV infection. Two types of clinical specimens were collected: peripheral blood leucocytes (PBLs) from 12 patients with HCMV-positive viremia and cerebro-spinal fluids (CSF) from five patients with HCMV-encephalitis. Comparison of US28 nucleotide sequences between clinical specimens and several HCMV reference strains showed that mutations were clustered at both ends of the gene. The mutations observed at the C-terminus were observed at some sequences whereas the mutations observed at the N-terminus lead us to define five patterns of mutations. These patterns were equally distributed among isolates obtained from CSF or PBLs of HIV-infected patients. For each clinical isolate, the gB genotype was determined. There was no genetic association between gB genotype and US28 patterns. The comparison of the results of the present study and those published from sequences obtained from children with HCMV congenital disease (Arav-Boger, 2002) demonstrates that two motifs appear especifically either in US28 protein sequences obtained from HIV-positive patients (motif 4) or in US28 protein sequences obtained from patients with congenital HCMV infection (motif 5/genotype B). The appearance of these patterns of mutations in other clinical context needs to be studied.

Cytomegalovirus excretion in children attending day-care centers

BACKGROUND

Healthy children attending day-care centers (DCC) may excrete cytomegalovirus (CMV) frequently. Mothers of children excreting CMV are at higher risk for acquiring this infection than mothers of children not excreting CMV. Despite the increased attendance to DCC by children there is a lack of information regarding CMV infection in Mexico.

METHODS

Prospective determination of CMV excretion in saliva of children attending public and private DCC. Three saliva samples were collected during a 2-month follow-up period from participating children and the presence of CMV was determined by viral culture. Demographic features of children and DCC type were taken into account when comparing children with and without CMV excretion.

RESULTS

One hundred fifty-two children participated in the study (84 from public and 68 from private DCC). Overall, 17 (11.2%) children excreted CMV during the study period. Excretion rates varied between DCC from 3.1 to 31.3%. Children from private DCC were as likely to excrete CMV as children from public DCC. There were no demographic or clinical features of children associated with viral excretion.

CONCLUSIONS

CMV was excreted on an average of 11.2% children attending DCC. The type of DCC or other demographic features were not associated with the likelihood of CMV excretion. CMV seronegative mothers of children who attend DCC need to be aware of the possibility of CMV acquisition and transmission in DCC.

Inter- and intra-person cytomegalovirus infection in Malawian families

Sequence polymorphisms in the gN and gO genes of cytomegalovirus (CMV) amplified from mouth rinse and urine samples of 19 Malawian patients with Kaposi's sarcoma (KS) and 58 of their first-degree relatives were investigated. CMV-DNA was amplified from 41 people (53%) from either the gN or gO region in at least one sample, from 14 people (18%) in both domains in at least one sample, and from 13 (17%) in either domain in both samples. Twenty-one (51%) were seropositive for human immunodeficiency virus-1 (HIV). Identical gN sequences were recovered from eight families and non-identical sequences in six, while identical gO sequences were found in three families and non-identical sequences in five. Five people, four of whom were children, each carried multitypic gN sequences or gO sequences. The findings are consistent with CMV spread along intra- and extra-household routes, and with multiple intra-host CMV infection.

Cytomegalovirus DNA among children attending two day-care centers in Tokyo

BACKGROUND

In the USA, a high prevalence rate of cytomegalovirus (CMV) excretion among children in day-care centres was reported. However, there is no research about the prevalence rate of CMV among children in day-care centres in Japan.

METHODS

The CMV excretion was studied in 54 children's saliva samples, collected from two different day-care centres in Tokyo. As a control, the prevalence of CMV was studied among 61 healthy children who did not attend any day-care centers. The CMV DNA in saliva were examined by polymerase chain reaction (PCR) analysis with one pair of primers for the immediate early region. The sequence of CMV genomes were examined in CMV PCR positive samples.

RESULTS

Of the 54 saliva samples, 20.6% (6/29) and 24% (6/25) were CMV PCR positive in children at A and B day-care centres, respectively. The overall positivity of CMV PCR in saliva was 22.2% (12/54). Of the 61 saliva samples as the control study, 6.5% (4/61) were CMV PCR positive. There was a difference in the positivity in each age group of day-care centres and normal control. Each sample of the same day-care center gave conclusive and identical sequence results.

CONCLUSION

We suspected that in each day-care center that there was one prevailing viral strain. We suppose that CMV infections were acquired inside the day-care centres. This is a first report which described viral transmission in day-care centres in Japan.

A polymorphism in the major immediate-early gene delineates groups among cytomegalovirus clinical isolates

Major immediate-early gene exon 4 sequences were determined at codons 161-241 and 254-397 in 25 cytomegalovirus clinical strains and compared with those of reference strains AD169 and Towne. The nucleotide sequences at codon 161-241 segregated into three groups which could be determined by restriction mapping of a 247-nucleotide amplified target. AD169 and Towne belonged to the same group. Clustered variations and group-specific amino-acid motifs found in the deduced peptide sequence of the two immediate-early (IE) exon 4 regions raised a question is to the effects of polymorphism on IE1 function and/or immunogenicity. On the basis of restriction analysis of polymerase chain reaction (PCR) products, virus isolates were also classified into four glycoprotein B (gB) genotypes. Strain distribution in IE1 and gB genotypes showed a lack of concordance of the two grouping methods, and no preferential association was observed between the clinical context or kind of specimen and IE1 or gB groups. These data lead up to further prospective studies which could provide important information on the implication of the MIE gene region in virus pathogenesis and indicate whether linkage unbalance exists in particular clinical contexts between IE1 and gB loci.