High frequency of parvovirus B19 DNA in bone marrow samples from rheumatic patients

Karolinska University Hospital, Tukholma, Stockholm, Sweden
Journal of Clinical Virology (Impact Factor: 3.47). 06/2005; 33(1):71-4. DOI: 10.1016/j.jcv.2004.11.011
Source: PubMed

ABSTRACT Human parvovirus B19 (B19) polymerase chain reaction (PCR) is now a routine analysis and serves as a diagnostic marker as well as a complement or alternative to B19 serology. The clinical significance of a positive B19 DNA finding is however dependent on the type of tissue or body fluid analysed and of the immune status of the patient.
To analyse the clinical significance of B19 DNA positivity in bone marrow samples from rheumatic patients.
Parvovirus B19 DNA was analysed in paired bone marrow and serum samples by nested PCR technique. Serum was also analysed for B19-specific IgG and IgM antibodies and the results were compared with clinical and epidemiological data.
B19 IgG was found in 41 of 50 patients (82%) whereas none was B19 IgM positive. The serologic evaluation showed that none of the patients had acute B19 infection. However, B19 DNA was detected by PCR in 13 of 50 (26%) bone marrow samples from these patients indicating a high frequency of persistent infection compared with previous reports of patient groups and healthy controls. In the study, 22 patients had rheumatoid arthritis (RA) and 7 of these RA patients were B19 DNA positive in bone marrow. Rheumatoid factor was positive in 4 of the 7 B19 DNA positive RA patients as compared with Rheumatoid factor positivity in all of the 15 B19 DNA negative RA patients. Erosive arthritis in X-ray was less common in the B19 DNA positive group than in the B19 DNA negative group. A high frequency of parvovirus B19 DNA was thus detected in bone marrow samples in rheumatic patients. The clinical data does not support a direct association between B19 PCR positivity and rheumatic disease manifestation. Therefore, the clinical significance of B19 DNA positivity in bone marrow samples from rheumatic patients must be interpreted with caution.

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    ABSTRACT: Human parvovirus B19 is a minute ssDNA virus causing a wide variety of diseases, including erythema infectiosum, arthropathy, anemias, and fetal death. After primary infection, genomic DNA of B19 has been shown to persist in solid tissues of not only symptomatic but also of constitutionally healthy, immunocompetent individuals. In this thesis, the viral DNA was shown to persist as an apparently intact molecule of full length, and without persistence-specific mutations. Thus, although the mere presence of B19 DNA in tissue can not be used as a diagnostic criterion, a possible role in the pathogenesis of diseases e.g. through mRNA or protein production can not be excluded. The molecular mechanism, the host-cell type and the possible clinical significance of B19 DNA tissue persistence are yet to be elucidated. In the beginning of this work, the B19 genomic sequence was considered highly conserved. However, new variants were found: V9 was detected in 1998 in France, in serum of a child with aplastic crisis. This variant differed from the prototypic B19 sequences by ~10 %. In 2002 we found, persisting in skin of constitutionally healthy humans, DNA of another novel B19 variant, LaLi. Genetically this variant differed from both the prototypic sequences and the variant V9 also by ~10%. Simultaneously, B19 isolates with DNA sequences similar to LaLi were introduced by two other groups, in the USA and France. Based on phylogeny, a classification scheme based on three genotypes (B19 types 1-3) was proposed. Although the B19 virus is mainly transmitted via the respiratory route, blood and plasma-derived products contaminated with high levels of B19 DNA have also been shown to be infectious. The European Pharmacopoeia stipulates that, in Europe, from the beginning of 2004, plasma pools for manufacture must contain less than 104 IU/ml of B19 DNA. Quantitative PCR screening is therefore a prerequisite for restriction of the B19 DNA load and obtaining of safe plasma products. Due to the DNA sequence variation among the three B19 genotypes, however, B19 PCR methods might fail to detect the new variants. We therefore examined the suitability of the two commercially available quantitative B19 PCR tests, LightCycler-Parvovirus B19 quantification kit (Roche Diagnostics) and RealArt Parvo B19 LC PCR (Artus), for detection, quantification and differentiation of the three B19 types known, including B19 types 2 and 3. The former method was highly sensitive for detection of the B19 prototype but was not suitable for detection of types 2 and 3. The latter method detected and differentiated all three B19 virus types. However, one of the two type-3 strains was detected at a lower sensitivity. Then, we assessed the prevalence of the three B19 virus types among Finnish blood donors, by screening pooled plasma samples derived from >140 000 blood-donor units: none of the pools contained detectable levels of B19 virus types 2 or 3. According to the results of other groups, B19 type 2 was absent also among Danish blood-donors, and extremely rare among symptomatic European patients. B19 type 3 has been encountered endemically in Ghana and (apparently) in Brazil, and sporadical cases have been detected in France and the UK. We next examined the biological characteristics of these virus types. The p6 promoter regions of virus types 1-3 were cloned in front of a reporter gene, the constructs were transfected into different cell lines, and the promoter activities were measured. As a result, we found that the activities of the three p6 promoters, although differing in sequence by >20%, were of equal strength, and most active in B19-permissive cells. 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Raskauden aikana virus voi siirtyä äidistä sikiöön aiheuttaen jopa sikiön kuoleman. B19-virus lisääntyy luuytimessä, punasolujen esiasteissa, joten se voi tiettyjä veritauteja sairastaville henkilöille aiheuttaa rajun lyhytkestoisen anemian, joka hoitamattomana voi olla kohtalokas. Immuunipuutteiset henkilöt voivat sairastua vuosienkin mittaiseen anemiaan. Parvorokkoviruksen aiheuttama niveltulehdus on yleinen etenkin naisilla ja kestoltaan sekä vaikeusasteeltaan vaihteleva, vaikeimmat tapaukset jopa nivelreuman kaltaisia. Tässä työssä löysimme uuden, ennestään tuntemattoman parvovirusvariantin (LaLi), joka perimäainekseltaan eroaa sekä B19-prototyypistä että vuonna 1998 löydetystä V9-variantista. Nykyisin parvorokkovirukset jaetaankin kolmeen tyyppiin: perinteiset isolaatit kuuluvat tyyppiin 1, LaLi:n kaltaiset tyyppiin 2 ja V9:n kaltaiset tyyppiin 3. 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Lisäksi tarkastelimme uusien virustyyppien esiintyvyyttä suomalaisten verenluovuttajien keskuudessa seulomalla n. 140 000 luovuttajan näytteet: tästä joukosta löytyi ainoastaan tyyppiä 1. Toisin sanoen, vaikka tyypin 2 DNA:ta löytyi yleisesti terveiden henkilöiden ihonäytteistä, tyypin 2 virusta ei suomalaisten verenluovuttajien keskuudessa havaittu. Vertaillessamme B19-prototyypin ja uusien B19-tyyppien biologisia ominaisuuksia sekä infektiokykyä soluviljelmissä osoitimme, että myös uudet parvorokkovirustyypit ovat biologisesti aktiivisia, infektiokykyisiä viruksia. Lisäksi vertailimme tyyppien 1 ja 2 immunologiaa ja vasta-ainediagnostiikkaa: osoitimme että kumpaa tahansa virustyyppiä kohtaan muodostuneet vasta-aineet tunnistavat myös toisen virustyypin, ja näyttäisivät suojaavan kummankin virustyypin uusintainfektioilta.
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    Virus Research 01/2006; 114(1-2-114):1-5. DOI:10.1016/j.virusres.2005.05.003 · 2.83 Impact Factor
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