Detection of immunoperoxidase labelled mycoplasmas in cell culture by light microscopy and electronmicroscopy

A McCoy cell line persistently infected with Mycoplasma orale was examined by light microscopy and electronmicroscopy after specific labelling with a direct immunoperoxidase conjugate. Mycoplasmas were readily detected in monolayer cultures in bright-field conditions and these were related to labelled organisms observed by electronmicroscopy in thin sections of similar cells. The specificity of the conjugate for M. orale was demonstrated by blocking with unconjugated antiserum, and by its inability to detect M. bovirhinis. Non-specific background labelling was consistently absent.