Departments of Medicine,
2 Medical Microbiology and
3 Virology, Turku University, Turku,
1 Satalinna Hospital, Harjavalta and 3Ilomantsi Health Center, Ilomantsi, Finland
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Abstract |
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Methods. Twenty-six patients with earlier serologically confirmed Pogosta disease were examined. Ultrasonography of affected joints was performed in patients who had chronic musculoskeletal symptoms. Serum antibodies against Sindbis virus were determined. The patients were typed for HLA-DR and B27. Efforts were made using the polymerase chain reaction to demonstrate the virus.
Results. Only 50% of the patients were symptomless 2.5 yr after onset of Pogosta disease. Three patients had fibromyalgia, six had occasional arthralgia and two had chronic arthritis.
Conclusions. The epidemiology of Pogosta disease is changing and practitioners should be better aware of it. Pogosta virus infection may lead to chronic musculoskeletal discomfort and arthritis.
KEY WORDS: Pogosta disease, Sindbis virus, Chronic arthritis.
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Introduction |
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Similar diseases have been reported to occur in Sweden (Ockelbo disease) and in Russia (Karelian fever) [4, 5]. In Ockelbo disease, chronic arthralgias have been described 34 yr after the infection [6]. Disease caused by Ross River virus has been reported to be followed by chronic fatigue syndrome lasting up to 3 yr after the infection [7]. The prognosis of Pogosta disease is considered to be good, but so far no long-term follow-up studies have been carried out.
The purpose of our study was to investigate the duration of the joint symptoms in Pogosta disease. Until now, studies of the chronicity of the joint symptoms have been based only on questionnaires. We took advantage of the fact that 2.5 yr earlier there had been an outbreak of Pogosta disease in southwestern Finland. We also wanted to study whether the clinical features of Pogosta disease in southwestern Finland are similar to those in eastern Finland [3].
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Materials and methods |
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A specimen for serological studies was taken and erythrocyte sedimentation rate, C-reactive protein, haemoglobin, blood leukocytes and rheumatoid factor were assessed for all patients. We obtained a synovial tissue specimen from one patient with chronic arthritis.
Samples
From each patient, 10 ml whole blood and 10 ml blood were taken for serum separation. The serum samples were divided into aliquots that were stored at -135°C until tested. The lymphocytes were collected by centrifugation after Ficoll-Paque gradient separation and were stored as pellets at -135°C until use. The lymphocytes were homogenized with a QIAshredder (Qiagen, Hilden, Germany) and the samples were prepared for extraction of nucleic acids by isolating RNA from the lymphocytes with a Rneasy minikit (Qiagen) and then diluting the isolated RNA to 60 µl with nuclease-free sterile water (Amresco, Solon, OH, USA).
Reverse transcriptionpolymerase chain reaction
The cDNA was synthesized using the AMV first-strand cDNA synthesis kit for reverse transcriptionpolymerase chain reaction (RTPCR) (Boehringer Mannheim, Indianapolis, Indiana, USA). For RT we used the reaction primer KIP 124 [8], and 8 µl RNA isolated from lymphocytes and sera was used as a template. The cDNA generated by the RT described above was amplified by PCR. The total PCR volume was 100 µl and contained 5 mM MgCl, 1.25 mM dNTP, 2 units AmpliTag Gold polymerase (Perkin-Elmer, Foster City, CA, USA), 10 mM Tris (pH 8.3), 50 mM KCl and 10 pmol of the primers OCK 1 and OCK 2, as described by Hörling et al. [8]. The primers were synthesized with an Applied Biosystems 391 DNA synthesizer (PCR-MATE) [8].
The samples were amplified in a Perkin-Elmer thermal cycler under the following conditions: 45 cycles of 95°C for 1 min, 53°C for 45 s and 72°C for 30 s. Ten microlitres of the amplified product was analysed by 1.5% agarose gel electrophoresis and visualized by UV fluorescence after staining with ethidium bromide.
Precautions to avoid false-negative and false-positive PCR results.
To analyse the quality of the extracted RNA and to estimate the presence of components inhibiting RTPCR, ß-ACT genes were transcribed and amplified. The primers used for transcription have been described by Melby et al. [9]. The cDNA was synthesized using primers ß-ACT 2 and the AMV first-strand cDNA synthesis kit for RTPCR (Boehringer Mannheim). The ß-ACT cDNA was amplified as described by Halminen et al. [10] except that the number of PCR cycles was 35 rather than 31.
Special care was taken from the beginning of our studies to avoid contamination of samples with amplicons [11]. Clinical material was handled whenever possible in laminar flow hoods. Extraction of RNA, preparation of cDNA, preparation of PCR and analysis of PCR products were all performed in different rooms. ART Self-Sealing Barrier tips (MßP, San Diego, CA, USA) were used to pipette the specimens. Negative controls were included in all phases.
HLA typing
HLA-DR typing by PCR amplification was performed as described by Olerup et al. [12]. HLA-B27 typing was carried out by a PCR method described by Välimaa et al. [13].
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Results |
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Arthritis was diagnosed both clinically and with the aid of ultrasonography in two patients, who were both women. One of them had swelling and tenderness in the proximal interphalangeal joints of the hands, and the other in the metatarsophalangeal joints.
The erythrocyte sedimentation rate varied from 5 to 39 mm/h and C-reactive protein from < 10 to 25 mg/l; it was normal in 23 patients. One patient was positive for rheumatoid factor (Table 2).
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Human leukocyte antigen types B27 and DR4 were tested: only two of 21 patients were B27-positive and six of 22 were DR4-positive.
All serum specimens and lymphocyte preparations were negative for viral RNA by PCR.
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Discussion |
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We also wanted to study the time course of musculoskeletal symptoms after Pogosta disease, and were surprised by the high percentage of patients with various chronic sequelae and symptoms still present 2.5 yr after the onset of Pogosta disease. Only 13/26 patients were symptomless, and altogether 11 had chronic musculoskeletal symptoms and findings that may be due to the Pogosta virus infection. In addition to this, in two patients the pain caused by osteoarthritis had worsened after the onset of Pogosta disease. Three patients had fibromyalgia. It is known that several virus infections may lead to a chronic fatigue syndrome, and it has been reported that, after infection with Sindbis-related Ross River virus, 45% of patients complained of persistent tiredness and lethargy [7]. Unfortunately, no proper control material was obtained. However, we feel that the presence of symptoms in 13/26 patients exceeds the prevalence of them in the normal population.
The most interesting cases were those patients who still had chronic arthritis at the time of our study. There have been reports of chronic arthritis after parvovirus B19 virus infection and B19 DNA has been detected in the synovial tissue of such patients [14, 15]. It would also be interesting to see whether the patients who now have occasional arthralgia will have chronic relapsing arthralgia permanently.
Several investigators have postulated that members of the Old World complex of alphaviruses (Ockelbo, chikungunya and Ross River viruses) may persists in humans, since some patients develop persistent arthralgias after acute infection with these viruses [6, 16]. The detection of IgM antibodies against Pogosta virus and also against Ockelbo and Ross River viruses for prolonged periods after acute infection suggests that there is continuous expression of viral antigen [16]. This supports the hypothesis that alphavirus persistence is involved in the development of chronic musculoskeletal symptoms [16]. We have now studied the persistence of Pogosta virus RNA in peripheral blood cells and patients' sera by RTPCR, but the results were negative. Ockelbo virus RNA has been demonstrated in skin biopsies in acute Ockelbo infection but there are no findings of viral RNA in any clinical human tissues in patients with chronic symptoms [17]. We also tested Pogosta virus RNA from a synovial tissue specimen of the patient with chronic arthritis, but the results were also negative.
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Acknowledgments |
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Notes |
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References |
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