Lack of evidence for a direct involvement of muscle infection by parvovirus B19 in the pathogenesis of inflammatory myopathies: a follow-up study

Objective. To clarify the association between parvovirus B19 and myositis. Methods. Biopsy samples of muscle from eight patients with inflammatory myopathies were studied for the presence of B19 DNA by polymerase chain reaction. Expression of VP1 and VP2 capsid proteins was evaluated by immunohistochemistry. Interleukin 6 (IL-6) production was measured in the supernatant of myoblasts following incubation with parvovirus B19. Results. In seven samples, detection of B19 DNA was negative. The expression of VP1 and VP2 capsid proteins was not observed by immunohistochemistry. In one patient, detection was transiently positive but became negative despite a flare-up of muscle disease. In vitro, parvovirus B19 was not able to induce IL-6 production by myoblasts. Conclusion. Our results do not support the direct implication of parvovirus B19 in the pathogenesis of myositis.