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Cytomegalovirus labyrinthitis in an infant: morphological, virological, and immunofluorescent studies
Abstract:
The inner ears obtained from an infant who died of severe congenital cytomegalovirus infection were examined using virological and morphological methods. The techniques of microdissection and surface preparations, immunofluorescent microscopy, and transmission and scanning electron microscopy were employed. Cytomegalovirus was isolated from the perilymph. Injury to the cochlea was minor and was confined to the first half of the basal turn. There were signs of a severe labyrinthitis of the vestibular endolymphatic system. Vestibular organs, especially the saccule and utricle, showed severe damage, with collapse of the saccular membranous wall. Inclusion-bearing cells containing cytomegalovirus antigen, as shown by immunofluorescent staining, and cytomegalovirus virions, as observed by electron microscopy, were found on the endolymphatic surface of the membranous walls, mainly in the saccule and utricle. In the utricle, the infected cells appeared to be concentrated in the regions where the so-called dark cells were located. These dark cells are similar to the proximal tubule cells in the kidney, another common target for cytomegalovirus infection.
Insights
Congenital cytomegalovirus infection severely damaged the infant
Area of Science:
- Otolaryngology
- Virology
- Pathology
Background:
- Congenital cytomegalovirus (CMV) infection is a leading cause of sensorineural hearing loss.
- The specific mechanisms of inner ear damage in congenital CMV infection are not fully understood.
Observation:
- Virological and morphological examination of inner ear tissues from an infant with severe congenital CMV infection.
- Utilized microdissection, surface preparations, immunofluorescent microscopy, and electron microscopy.
Findings:
- Cytomegalovirus (CMV) was isolated from the perilymph.
- Minor cochlear injury was observed, primarily in the basal turn.
- Severe labyrinthitis affected the vestibular endolymphatic system, with significant damage to the saccule and utricle, including collapse of the saccular wall.
- CMV virions and antigen-bearing cells were identified on the endolymphatic surfaces of the saccule and utricle, particularly in dark cells of the utricle.
- Dark cells in the utricle, similar to kidney proximal tubule cells, were identified as a site of CMV infection.
Implications:
- This study provides direct evidence of CMV's pathological effects on the vestibular system in congenital infection.
- The findings highlight the saccule and utricle as primary targets for CMV in the inner ear.
- Understanding these mechanisms may inform strategies for preventing or treating CMV-induced vestibular dysfunction.