No evidence of measles virus in stapes samples from patients with otosclerosis

Otosclerosis is a localized bone dystrophy of unknown etiology mainly invol ving the stapes. The hypothesis of a persistent infection by the measles vi rus was based on the inconstant detection of the virus by various methods, including reverse transcription-PCR (RT-PCR) of patients' stapes samples. T he aim of this work was to investigate the presence of the measles virus in stapedial otosclerosis foci by different sensitive methods, Patho logic st apes samples were obtained from 35 patients suffering from otosclerosis, Me asles virus detection was performed by (i) cocultures of Vero cells and pri mary cell cultures of bone samples (n = 7), (ii) immunofluorescence study o f these cocultures (n = 3), and (iii) RT-PCR on RNA directly obtained from fresh frozen samples (n = 28) and on RNA extracted from the primary cell cu ltures (n = 2), Viral genomic regions coding for N (nucleoprotein) and M (m atrix) proteins were separately amplified. PCR sensitivity was optimized on the measles virus Edmonston strain, Glyceraldehyde-3-phosphate dehydrogena se mRNA was used as a marker of total RNA recovery. PCR products were teste d by Southern blot hybridization technique to improve sensitivity and speci ficity. PCRs amplifying the M and the N protein genes were able to detect t he control measles virus RNA at titers as low as 0.1 acid 0.01 50% tissue c ulture infective dose, respectively, With these highly sensitive methods, w e could not evidence the presence of the measles virus in any of our bone s amples or primary bone cell cultures, Our results do not confirm the hypoth esis of persistent measles virus infection in otosclerosis.