Microfilaments associated with Paget's disease of bone: comparison with nucleocapsids of measles virus and respiratory syncytial virus.

The structural characteristics and intracellular disposition of microtubules present in osteoclasts in Paget's disease of bone were compared with those of nucleocapsids in cells infected with measles virus and respiratory syncytial virus (RSV). The distribution of microtubules in pagetic osteoclasts closely paralleled that of measles nucleocapsids in monkey kidney cells, but the dimensions of the pagetic microtubules were significantly different from those of measles virus. In contrast, pagetic microtubules were not distinguishable in dimensions from RSV nucleocapsids but were dissimilar in their conformation and location. The observations support the hypothesis tht Paget's disease of bone is a slow virus disease and suggest that the virus is a pneumovirus (RSV) rather than a morbillivirus (measles).