Breast milk transmission of cytomegalovirus (CMV) infection

Cytomegalovirus infections

Human cytomegalovirus, a human herpesvirus, remains a major cause of neurological disorders as a consequence of infections acquired in utero or postnatally. This article summarizes current information regarding the epidemiology, clinical manifestations, treatment, and prevention of this ubiquitous human infection.

Detection of perinatal cytomegalovirus infection and sensorineural hearing loss in belgian infants by measurement of automated auditory brainstem response

Since auditory disability causes serious problems in the development of speech and in the total development of a child, it is crucial to diagnose possible hearing impairment as soon as possible after birth. This study evaluates the neonatal hearing screening program in Flanders, Belgium. The auditory ability of 118,438 babies was tested using the automated auditory brainstem response. We selected 194 babies with indicative hearing impairment and 332 matched controls to investigate the association between the presence of human cytomegalovirus (HCMV) in urine samples and sensorineural hearing loss and to analyze the sensibility and specificity of a cell culture assay and a quantitative PCR detection method. Our results indicate that significantly more babies with confirmed hearing impairment were HCMV positive after birth. Further, based on the results of our study, babies with HCMV viral loads above 4.5 log copies/ml urine seem to be 1.4 times more likely to have confirmed hearing impairment. Our follow-up study suggests that the hearing impairment of children infected with HCMV after birth is less likely to improve than that of HCMV-negative infants. Our results confirm that the presence of HCMV before or shortly after birth influences the outcome of hearing impairment.

Herpesviridae infections in newborns: varicella zoster virus, herpes simplex virus, and cytomegalovirus

Varicella zoster virus (VZV), herpes simplex virus (HSV) and cytomegalovirus (CMV) are all members of the Herpesviridae family.Humans are the only source of infection for these double stranded DNA viruses. Infants may acquire these infections in utero, peripartum, or postnatally, resulting in a variety of clinical syndromes, ranging from asymptomatic infection to severe infection,with high mortality rates and significant long-term morbidity. This article presents the epidemiology, clinical characteristics, treatment,and prevention strategies for VZV, HSV, and CMV infections in infants.

Congenital and perinatal infections with cytomegalovirus

Congenital cytomegalovirus (CMV) infections remain the leading viral cause of congenital malformations in the developed world. Despite advances in our knowledge, the epidemiology and natural history of congenital CMV infection are still poorly understood, particularly in Australia. Congenital CMV causes illness ranging from no clinical disease (asymptomatic, but infected) through to prematurity, encephalitis, deafness and haematological disorders and death. Perinatal CMV acquisition usually results in less severe illness including asymptomatic infection, acute infection with hepatitis, fever, and pneumonitis. CMV infects only humans, and in vitro and in vivo models for intrauterine infection are required in order to test new treatments, and better describe the pathogenesis of congenital CMV. Using new knowledge of the epidemiology and natural history of CMV, treatment regimens during late pregnancy are currently undergoing clinical trial although no definitive recommendations are available.

Human cytomegalovirus strains associated with congenital and perinatal infections

The genotypes of human cytomegalovirus (HCMV) isolates from pediatric patients differs from those of infected adults in Australia. Genotypes were determined by PCR amplification of glycoprotein B (gB) sequences, with subsequent analysis by restriction fragment length polymorphism, single-stranded conformation polymorphism, heteroduplex mobility analysis and direct DNA sequencing. Restriction fragment length polymorphism analysis of gB showed genotypes gB1 (39%) and gB3 (30%) were more prevalent in infected children and two new genotypes (gB6 and gB7) were found. Single-stranded conformation polymorphism was used to group isolates into 22 further subtypes and suggested longitudinal co-infection or viral mutation was occurring over time. Heteroduplex mobility analysis was found to be the most accurate and concise of the four methods used for genotyping HCMV isolates. DNA sequencing was used to confirm the results obtained from heteroduplex mobility analysis, and identified two isolates that were incorrectly genotyped by restriction fragment length polymorphism analysis. Heteroduplex mobility analysis efficiently genotyped all samples and allowed estimation of sequence variation between isolates. These data suggest certain gB genotypes are associated more commonly with childhood infections, and these differ from strains associated with invasive disease in HIV patients.

Covalent modification of the transactivator protein IE2-p86 of human cytomegalovirus by conjugation to the ubiquitin-homologous proteins SUMO-1 and hSMT3b

The 86-kDa IE2 protein (IE2-p86) of human cytomegalovirus (HCMV) is a potent transactivator of viral as well as cellular promoters. Several lines of evidence indicate that this broad transactivation spectrum is mediated by protein-protein interactions. To identify novel cellular binding partners, we performed a yeast two-hybrid screen using a N-terminal deletion mutant of IE2-p86 comprising amino acids 135 to 579 as a bait. Here, we report the isolation of two ubiquitin-homologous proteins, SUMO-1 and hSMT3b, as well as their conjugating activity hUBC9 (human ubiquitin-conjugating enzyme 9) as specific interaction partners of HCMV IE2. The polypeptides SUMO-1 and hSMT3b have previously been shown to be covalently coupled to a subset of nuclear proteins such as the nuclear domain 10 (ND10) proteins PML and Sp100 in a manner analogous to ubiquitinylation, which we call SUMOylation. By Western blot analysis, we were able to show that the IE2-p86 protein can be partially converted to a 105-kDa isoform in a dose-dependent manner after cotransfection of an epitope-tagged SUMO-1. Immunoprecipitation experiments of the conjugated isoforms using denaturing conditions further confirmed the covalent coupling of SUMO-1 or hSMT3b to IE2-p86 both after transient transfection and after lytic infection of human primary fibroblasts. Moreover, we defined two modification sites within IE2, located in an immediate vicinity at amino acid positions 175 and 180, which appear to be used alternatively for coupling. By using a SUMOylation-defective mutant, we showed that the targeting of IE2-p86 to ND10 occurs independent of this modification. However, a strong reduction of IE2-mediated transactivation of two viral early promoters and a heterologous promoter was observed in cotransfection analysis with the SUMOylation-defective mutant. This suggests a functional relevance of covalent modification by ubiquitin-homologous proteins for IE2-mediated transactivation, possibly by providing an additional interaction motif for cellular cofactors.

A PCR based DNA hybridisation capture system for the detection of human cytomegalovirus. A comparative study with other identification methods

A simple, sensitive and specific colourimetric hybridisation method for the detection of HCMV DNA in clinical specimens is described. This method combines a PCR assay with a sensitive sandwich hybridisation assay. It relies on the use of a specific capture probe linked covalently to polystyrene microplates and a specific polybiotinylated detection probe. Amplified DNA fragments, sandwiched between these two probes, are detected by an enzymatic colour reaction. This PCR-based colourimetric hybridisation method was compared with other known HCMV detection methods. Clinical specimens (n = 145, corresponding to 106 patients) were tested by both a nested PCR assay and this colourimetric hybridisation method; and by either the culture method or the pp65 antigenaemia test depending on the type of sample used. The results showed that the PCR-based hybridisation method has a specificity similar to tissue culture, known as the conventional gold standard method, and could be used for the examination of the clinical specimens.