Prolonged myalgia in Sindbis virus infection: case description and in vitro infection of myotubes and myoblasts.

BACKGROUND: Sindbis virus (SINV) is a mosquito-borne alphavirus found in Eurasia, Africa, and Oceania. Clinical SINV infection is characterized by febrile rash and arthritis and sometimes prolonged arthralgia and myalgia. The pathophysiological mechanisms of musculoskeletal and rheumatic disease caused by SINV are inadequately understood. METHODS: We studied the muscle pathology of SINV infection ex vivo by examining a unique muscle biopsy obtained from a patient with chronic myalgia and arthralgia 6 months after acute SINV infection and assessed potential genetic predisposing factors by determining the human leukocyte antigen (HLA) and complement factor C4 genes and proteins. In addition, we performed in vitro SINV infections of primary human myoblasts and myotubes. RESULTS: In the muscle biopsy we found evidence of muscle regeneration due to previous necrotic lesions likely caused by earlier SINV infection. We showed that human myoblasts and myotubes were susceptible in vitro for SINV infection as the cells became immunoreactive for viral antigens and cytopathic effect was observed. The patient was homozygous for HLA-B*35 alleles and heterozygous for HLA-DRB1*01 and HLA-DRB1*03 alleles and had total deficiency of C4B protein. CONCLUSIONS: This study provides new insights concerning pathological processes leading to chronic symptoms in SINV infection and demonstrates for the first time the susceptibility of human myogenic cells to SINV infection.

"Strawberry like" gingivitis being the first sign of Wegener's granulomatosis.

Wegener's granulomatosis (WG) is a rare granulomatous necrotizing vasculitis of small vessels, affecting vascular structures having predilection for upper airways. If untreated WG can be lethal. WG is also known to cause oral mucosal lesions. We report a case of WG that was first diagnosed on oral gingival mucosa. A 51-year old woman was referred to a specialized dentist because of consistent irritative buccal gingival hyperplasia that did not react to conservative and microbial treatment. The lesion was biopsied and the diagnosis was suggestive for WG. Patient was further referred to the Department of Rheumatology and the diagnose of WG was confirmed and treated. The oral lesions cured totally. This case emphasizes the importance to recognize the oral manifestation of WG to get proper medication as soon as possible and avoid serious systemic tissue damage.