Cytomegalovirus isolation from a human inner ear

Cytomegalovirus-induced pathology in human temporal bones with congenital and acquired infection

OBJECTIVE

Publications on histopathology of human temporal bones with cytomegalovirus (CMV) infection are limited. We aim to determine histopathology of the inner ears and the middle ears in human temporal bones with congenital and acquired CMV infections.

METHODS

Temporal bones from 2 infants with congenital and 2 adults with acquired CMV infection were evaluated by light microscopy.

RESULTS

Two infants with congenital CMV infection showed striking pathological changes in the inner ear. There was a hypervascularization of the stria vascularis in the cochlea of the first infant, but no obvious loss of outer and inner hair cells was seen in the organ of Corti. However, cytomegalic cells and a loss of outer hair cells were found in the cochlea of the second infant. The vestibular organs of both infants showed cytomegalic cells, mostly located on dark cells. There was a loss of type I and type II hair cells in the macula of the saccule and utricle. Loss of hair cells and degeneration of nerve fibers was also seen in the semicircular canals. Both infants with congenital infection showed abundant inflammatory cells and fibrous structures in the middle ear cavity. No evidence of cytomegalic cells and hair cell loss was found in the cochlea or vestibular labyrinth in acquired CMV infection.

CONCLUSIONS

In two infants with congenital CMV infection, the cochlea, vestibule, and middle ear were highly affected. Temporal bones of adult donors with acquired viral infection showed histological findings similar to donors of the same age without ear disease.

Herpes simplex virus-1 and cytomegalovirus DNAs detection in the inner ear of implanted patients with non-congenital infection

CONCLUSIONS

The detection of cytomegalovirus (CMV) and herpes simplex virus-1 (HSV-1) genome in perilymph of patients with negative serology or clinical history for congenital infections supports the hypothesis that Herpesviridae, even after acquired postnatal infections, could remain in latent phase in the spiral ganglion and damage the cochlea by a possible subsequent reactivation. Further studies are needed to identify the markers of such reactivation.

OBJECTIVE

To identify the presence of certain viral species in the endolabyrinthic fluid of deaf patients with non-congenital infection. The research of viral DNA within the inner ear is the only direct way to increase our knowledge about the viral role in postnatal damage to the cochlea.

METHODS

Thirty-six patients (1-69 years) suffering from bilateral sensorineural hearing loss (SNHL) were subjected, during cochlear implant (CI) surgery, to a sample taking of inner ear fluid. Several types of viral genome (HSV, VZV, CMV, EBV and Enterovirus) were investigated in each sample through multiplex polymerase chain reaction (PCR) and reverse transcriptase-polymerase chain reaction (RT-PCR). Radiological exams, serology (specific IgG and IgM) and PCR of peripheral blood were also performed.

RESULTS

While the research of the viral genome in peripheral blood was negative in all patients, multiplex PCR on endolabyrinthic fluid samples was positive in three patients (two cases of CMV-DNA and one case of HSV-1 DNA).

Human cytomegalovirus (HCMV) and hearing impairment: infection of fibroblast cells with HCMV induces chromosome breaks at 1q23.3, between loci DFNA7 and DFNA49 -- both involved in dominantly inherited, sensorineural, hearing impairment

Human cytomegalovirus (HCMV) infection is the most common congenital infection in developed countries and is responsible for a substantial fraction of sensorineural hearing impairment (SNHI) in children. The risk of hearing impairment is associated with viral load in urine and blood collected during the first postnatal month. However, although inner ear abnormalities are observed in some children with HCMV-induced SNHI, the exact mechanism whereby congenital HCMV infection causes hearing impairment is unknown. Earlier studies using standard cytogenetic mapping techniques showed that infection of S-phase human fibroblast cells with HCMV resulted in two specific, site-directed, chromosome breaks at band positions 1q21 and 1q42 which include loci involved in dominantly and recessively inherited hearing impairment, respectively. These findings suggested that cells infected with HCMV might provide a reservoir for genetic damage and, in a clinical perspective, a scenario could be envisioned whereby hearing impairment could result from early DNA damage of dividing fetal cells rather than viral replication and cell lysis. In this work we demonstrate, using fine mapping techniques, that HCMV infection in S-phase fibroblast cells induces genetic damage at 1q23.3, within a maximal region of 37 kb, containing five low copy repeat (LCR) elements. The breakpoint is situated between two hearing impairment (HI) loci, DFNA49 and DFNA7, and in close proximity to the MPZ gene previously shown to be involved in autosomal dominant Charcot-Marie-Tooth syndrome (CMT1B) with auditory neuropathy.

Pathogenesis of cytomegalovirus-associated labyrinthitis in a guinea pig model

Cytomegalovirus infects fetuses through the placenta, resulting in various congenital disorders in newborns, including hearing loss. We developed a monoclonal antibody to guinea pig cytomegalovirus (GPCMV) that was available for immunohistochemistry, and investigated the expression of the GPCMV antigen in animal models of direct and congenital infections. Injection of GPCMV, directly to the inner ear, increased the sound pressure level and resulted in labyrinthitis with severe inflammation. Immunohistochemistry detected GPCMV-infected cells mainly in the scala tympani, scala vestibule and spinal ganglion, but rarely in the cochlear duct. Injection of GPCMV to 5-week pregnant guinea pigs resulted in severe labyrinthitis in fetuses. Immunohistochemistry detected GPCMV-infected cells in the perilymph area and spinal ganglion, but not in the endolymph area, including hair cells. These data suggest that the virus spreads via the perilymph and neural routes in the inner ear of both models of direct and congenital infections.

Cytomegalovirus in the Perilymphatic Fluid

OBJECTIVE

The incidence of congenital cytomegalovirus (CMV) infection is approximately 1% of neonates. Ninety percent of congenitally infected infants are "asymptomatic;" they have no signs or symptoms at birth. The prevalence of congenital CMV in the profoundly deaf population and the pathogenesis of deafness from CMV are unknown. The objective of this study is to determine whether CMV can be demonstrated and quantified in perilymphatic fluid of patients with congenital CMV infection and sensorineural hearing loss (SNHL) using a quantitative real-time polymerase chain reaction (QRTPCR).

STUDY DESIGN

Prospective case series.

METHODS

Perilymphatic fluid was collected at the time of cochlear implantation from children with known or radiologic evidence of congenital CMV infection and analyzed for the presence of CMV using QRTPCR. Blood was collected and analyzed for CMV using QRTPCR, serology, and culture. CMV was quantified in perilymphatic fluid and compared with that present in the patient's blood.

RESULTS

Perilymphatic fluid and blood was collected from six children. QRTPCR was positive for CMV in the perilymphatic fluid of four patients. Blood analyzed with QRTPCR, and culture was negative in all patients.

CONCLUSIONS

CMV can be demonstrated and quantified in perilymphatic fluid using QRTPCR. Refinements in our technique and sampling of perilymphatic fluid from a large population of children with congenital SNHL and unknown etiology can determine the prevalence of CMV-mediated profound HL.

The pathology of the temporal bones of a child with acquired cytomegalovirus infection: studies by light microscopy, immunohistochemistry and polymerase-chain reaction

STUDY DESIGN

The first case of an acquired cytomegalovirus (CMV) infection of the inner ear is reported in a 3-year-old girl in remission from acute lymphocytic leukemia.

METHODS

Horizontal sections of the temporal bones were studied by light microscopy and immunohistological staining by avidin-biotin-complex-technique was performed on selected archival sections. Three sections were processed for detection of the virus genome by the polymerase chain reaction (PCR).

RESULTS

By light microscopy the epithelium of the endolymphatic sac, the utricle and the semicircular canals showed deeply stained acidophilic inclusions and the stria vascularis had a loose structure especially in the intermediate layer. The changes were limited to the non-sensory parts of the labyrinth and no CMV type cells were observed in the organ of Corti. There was a loss of inner and outer hair cells and loss of cochlear ganglion cells caused by either the virus or treatment with gentamicin. Standard immunohistochemistry failed to demonstrate staining with CMV antibodies, but PCR, demonstrated CMV-DNA in one section.

CONCLUSION

Molecular techniques may be able to detect acquired CMV infections in archival pediatric bones temporal bones. The histologic findings in the labyrinth were milder, however showed some similarity to children with congenital CMV labyrinthitis.

Serum antibodies to human herpesvirus 7, human herpesvirus 6 and cytomegalovirus in patients with idiopathic facial nerve palsy or sudden deafness

The aetiology of idiopathic facial nerve palsy (Bell's palsy) and sudden deafness are not known, although viruses have been suspected as a cause of them. We investigated the relationship between Bell's palsy or sudden deafness, and reactivation of cytomegalovirus, human herpesvirus 6 (HHV-6) and 7 (HHV-7). Paired sera were collected from 22 patients with Bell's palsy and 24 patients with sudden deafness. IgG antibody titres to HHV-7 were increased in one patient with Bell's palsy. IgG antibody titres to HHV-6 were increased in one patient with Bell's palsy and two with sudden deafness. IgG antibody titres to cytomegalovirus were increased in one patient with sudden deafness. Titres of the three viral antibodies were not increased simultaneously in any patients. These viruses may contribute to the development of Bell's palsy or sudden deafness in some cases. It is, however, unlikely that these viruses are the main cause of Bell's palsy and sudden deafness in the majority of patients.

Immunological and virological study of sudden deafness

Thirty-three patients with sudden deafness and 11 controls were selected from the patients admitted to the Department of Otolaryngology, Tokai University Hospital from November 1990 to October 1991. Viral titers were measured for mumps, adenovirus, rubella, measles, herpes simplex virus (HSV), varicella zoster virus (VZV), rhinosyncytial virus, cytomegalo-virus (CMV), and mycoplasma pneumoniae in 33 sudden deafness patients and 11 controls at a 2-week interval. In 20 of 33 sudden deafness patients and 5 of 11 controls, autoantibodies of rheumatoid factor (RF), anti-mitochondrial antibody (AMA), anti-nuclear antibody (ANA), anti-parietal cell antibody (APA), anti-smooth muscle antibody (ASA), and anti-type II collagen antibody were studied. Viral titer study did not reveal any significant change either in the patients or in the controls, whereas autoantibody study revealed a relatively high incidence for ASA in the patients as compared with the controls. The relatively high incidence for ASA suggests that immune-mediated processes may be involved in the etiology of sudden deafness.

Human spumaretrovirus in the etiology of sudden hearing loss

The etiology of sudden sensorineural hearing loss, so called sudden deafness, has for long puzzled researchers. Recently we have studied the possibility that a hitherto relatively unknown retrovirus group consisting of human spumaretroviridae (HSRV) might be the causative agent of sudden deafness. During the last 3 months we have screened about 30 cases of sudden deafness. In 4 of them antibodies against HSRV were detected. Three of them had suffered from a flu-like condition about 2 weeks before the onset of hearing loss. In 2 cases the hearing of both ears was involved, in 1 case a relapsing hearing loss was observed, and 1 case developed a Meniere-like symptomatology with a fluctuant hearing loss. Vertigo was present in 3 patients and all suffered from tinnitus. Full recovery of hearing was observed in 4 of 6 affected ears whereas 2 ears became practically deaf with poor speech discrimination. At present it seems likely that a significant part of sudden deafness is caused by HSRV infection. The course of infection follows the spontaneous course of sudden deafness described by many authors. We encourage otologic units to screen for HSRV when assessing the etiology of sudden deafness.

Experimental congenital cytomegalovirus labyrinthitis and sensorineural hearing loss

Cytomegalovirus is a leading cause of human congenital viral infection and hearing loss. The pathogenesis of human congenital cytomegalovirus infection is poorly understood. We have developed a reproducible model of congenital cytomegalovirus-induced sensorineural hearing loss in guinea pigs. This report reviews our previously published results and provides additional new information about this model.

Temporal sequence of viral antigen expression in the cochlea induced by cytomegalovirus

Injection of guinea-pig cytomegalovirus into seronegative guinea pig cochleas results in viral labyrinthitis. The location of infected cells 1-8 days following inoculation was examined using an immunohistochemical assay for viral antigens. Mesothelial cells below the basilar membrane and those lining the scala tympani, especially below the osseous spiral lamina, were the first cells to express antigen. This occurred 2 days following inoculation. Infection then spread rapidly toward the brain and through the perilymphatic duct to involve inflammatory cells, mesothelial cells of Reissner's membrane, spiral ganglion cells, and the vestibular ganglion cells. In any one cochlea, more mesothelial cells and inflammatory cells expressed viral antigen than any other cell type. It seems then, that there is a differential susceptibility to viral infection and antigen expression in the various cell types of the cochlea. Typical cytomegalic inclusions were common in mesothelial cells. However, many cells labelled for viral antigens did not contain inclusions. The identification of viral antigens then, is a more sensitive technique for demonstrating infection than is the location of cytomegalic inclusion cells.

Infection of the fetus and the newborn: prevention, treatment and related handicap

Congenital infection is uncommon and the cause of only a small proportion of handicap seen in children but some infections may be preventable or even treatable. As an example, the congenital rubella syndrome first described in the 1940s is preventable by use of the vaccine but cases still occur. It is hoped that with the introduction of the measles, mumps, rubella immunization for young children, rubella will become as rare in the UK as it is in the USA. Cytomegalovirus is now a more common cause of handicap than rubella but no vaccine has been developed. Although antiviral drugs are available for herpes simplex virus and vaccinia, infection mortality in the newborn is high, even following the use of these agents; many HSV infections in the newborn arise following primary and asymptomatic maternal infections so that treatment may start late in the course of the illness. The obstetrician needs to understand the natural history as well as possible investigations available for congenital infections. There may be warning signs which require action, such as herpetic lesions in the genital tract of the mother. Less specific abnormalities during pregnancy, such as intra-uterine growth retardation and spontaneous onset of preterm labour, may point to congenital infection. This chapter describes both antenatal and postnatal management of the major congenital infections. We have included recent research data that should influence clinical practice; studies on HSV which suggest that, for women with a history of recurrent infection, routine viral culture of the genital tract at the end of pregnancy is unnecessary; reports from both the USA and the UK that rubella immunization performed inadvertently during early pregnancy has not resulted in the congenital rubella syndrome. The chapter would not have been complete without a discussion of human immunodeficiency virus, of concern to the obstetrician and midwife. There is still much to be learned about the natural history of this infection in both the mother and infant.

Hearing Loss in Experimental Cytomegalovirus Infection of the Guinea Pig Inner Ear: Prevention by Systemic Immunity

Guinea pig cytomegalovirus (GPCMV) has been used to establish a reproducible model of viral labyrinthitis and hearing loss. Cochlear function was assessed by electrophysiological recordings of cochlear microphonic (CM) and eighth nerve N1 compound action potential (AP) thresholds prior to and up to eight days following inoculation of the scala tympani. Inner ear inoculation of seronegative subjects with live GPCMV produced profound elevations in CM and AP thresholds: 70% of these subjects had their thresholds raised to the limits of the sound system throughout the tested frequency range of 0.10 to 32 kHz. Histopathologic effects associated with CM and AP threshold shifts were primarily limited to the perilabyrinthine compartment, and were greatest in the most basal cochlear turns. Systemic infection with GPCMV produced an immune response, but did not affect CM or AP thresholds. Subsequent inoculation of the inner ear of these seropositive animals with live GPCMV did not result in either CM or AP threshold shifts, or cochlear histopathology. Inoculations of inactivated virus into the inner ears of seronegative and seropositive animals produced only moderate CM and AP threshold effects. Primary GPCMV labyrinthitis thus results in significant cochlear dysfunction and histopathologic changes which are prevented by prior systemic infection with GPCMV.

Hearing impairments and vestibular abnormalities among children with subclinical cytomegalovirus

This paper strengthens the importance of neonatal screening in the early identification and etiological specification of hearing loss by demonstrating that subclinical cytomegalovirus (CMV) is the most common viral agent causing sensorineural hearing loss (SNHL) among pediatric patients. Consequently, if hearing impairment is found on neonatal screening, viral studies should be done at once. In addition to a survey of previous literature, these points are presented from a retrospective study of 14 children with SNHL caused by focal CMV. Moreover, vestibular studies are presented which suggest that hearing and vestibular impairments may operate independently of one another or conjointly in patients infected with CMV.