Human parvovirus B19 : tissue persistence and prevalence of prototypic and new variants

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. Furthermore, the infectivity of the three B19 types was examined in two B19-permissive cell lines. RT-PCR revealed synthesis of spliced B19 mRNAs, and immunofluorescence verified the production of NS1 and VP proteins in the infected cells. These experiments suggested similar host-cell tropism and showed that the three virus types are strains of the same species, i.e. human parvovirus B19. Last but not least, the sera from subjects infected in the past either with B19 type 1 or type 2 (as evidenced by tissue persistence of the respective DNAs), revealed in VP1/2- and VP2-EIAs a 100 % cross-reactivity between virus types 1 and 2. These results, together with similar studies by others, indicate that the three B19 genotypes constitute a single serotype.Parvorokkovirus eli B19 on hyvin yleinen ihmisiä infektoiva virus joka aiheuttaa ihmiselle monenlaisia sairauksia. Tavallisin on lapsilla ja nuorilla esiintyvä ihottumatauti, parvorokko. 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. Herkkiä geenimonistusmenetelmiä käyttämällä parvorokkoviruksen DNA:n on osoitettu säilyvän perusterveiden, oireettomien ihmisten kudoksissa vieläpä vuosia infektion jälkeenkin. Näin ollen kudosperäistä B19-DNA-löydöstä sellaisenaan ei voida käyttää taudinmääritykseen. Osoitimme myös tyypin 2 DNA:n varastoituvan ihmisten kudoksiin, jopa prototyyppiä yleisemmin. Kudosten parvorokkovirus-DNA:n varastointimekanismia ei vielä tunneta, mutta osoitimme virusgeenien säilyvän pilkkoutumatta ja muuntumatta. Vielä ei tiedetä kykenevätkö nämä varastoidut genomit joissain tilanteissa tuottamaan esim. RNA:ta, proteiineja tai jopa infektiivistä virusta, ja siten aiheuttamaan ihmisille myöhäiskomplikaatioita. Parvorokkoviruksen on osoitettu leviävän myös verituotteiden välityksellä. Evaluoimme verituotteiden seulontaan tarjolla olevat kaupalliset geenimonistusmenetelmät uusien virustyyppien suhteen ja osoitimme, etteivät kaikki käytössä olevat testit löydä uusia parvorokkovirustyyppejä. 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

The PNPLA-family phospholipases involved in glycerophospholipid homeostasis of HeLa cells

Mammalian cells maintain the glycerophospholipid (GPL) compositions of their membranes nearly constant. To achieve this, GPL synthesis and degradation must be coordinated. There is strong evidence that A-type phospholipases (PLAs) are key players in homeostatic degradation of GPLs, but the identities of the PLAs involved have not been established. However, some members of the Patatin-like phospholipase domain-containing proteins (PNPLAs) have been implicated. Accordingly, we knocked down all the PNPLAs significantly expressed in human HeLa cells using RNA interference and then determined whether the turnover of the major glycerophospholipids is affected by using mass spectrometry and metabolic labeling with stable isotope labeled precursors. Knockdown of PNPLA9, PNPLA6 or PNPLA4 significantly (30-50%) reduced the turnover of phosphatidylcholine, ethanolamine and-serine. In a notable contrast, turnover of phosphatidylinositol was not significantly affected by the knockdown of any PNPLA. Depletion of PNPLA9 and PNPLA4 also inhibited G(0)/G(1) G(1) to S cell cycle progression, which could thus be regulated by GPL turnover. These results strongly suggest that PNPLA9, -6 and -4 play a key role in GPL turnover and homeostasis in human cells. A hypothetical model suggesting how these enzymes could recognize the relative concentration of the different GPLs is proposed. (C) 2016 Elsevier B.V. All rights reserved.Peer reviewe

Granuloma Annulare and Morphea : Correlation with Borrelia burgdorferi Infections and Chlamydia-related Bacteria

A retrospective study of 109 skin biopsies with granuloma annulare (GA) or morphea histology from patients with suspected tick bite was performed. Biopsies were tested for cutaneous Borrelia burgdorferi DNA using PCR. The same biopsies were analysed for tick-borne novel agents, Chlamydia-related bacteria (members of the Chlamydiales order), using a PCR-based method. Borrelia DNA was detected in 7/73 (9.6%) biopsies with GA and in 1/36 (2.8 %) biopsies with morphea, while Chlamydiales DNA was found in 53/73 (72.6%) biopsies with GA and 25/34 (73.4%) biopsies with morphea. All Borrelia DNA-positive GA samples were also positive for Chlamydiales DNA. The Chlamydiales sequences detected in GA were heterogeneous and contained Waddliaceae and Rhabdochlamydiaceae bacteria, which are also present in Ixodes ricinus ticks, while the Chlamydiales sequences detected in morphea closely resembled those found in healthy skin. In conclusion, tick-mediated infections can trigger GA in some cases, while correlation of either Borrelia or Chlamydiales with morphea is unlikely.Peer reviewe

Chlamydiales Bacterial Sequences in Lesional and Healthy Skin of Patients with Parapsoriasis

Peer reviewe

Transcriptional Expression of the ompA, cpaf, tarp, and tox Genes of Chlamydia trachomatis Clinical Isolates at Different Stages of the Developmental Cycle

The transcriptional gene expression patterns of Chlamydia trachomatis have mainly been studied using reference strains propagated in cultured cells. Here, using five low-passage-number C. trachomatis clinical isolates that originated from asymptomatic or symptomatic female patients, the in vitro expression of the ompA, cpaf, tarp, and tox genes was studied with reverse transcriptase real-time PCR during the chlamydial developmental cycle. We observed dissimilarities in the gene expression patterns between the low-passage-number clinical isolates and the reference strains. The expression of ompA and the peak of the tox expression were observed earlier in the reference strains than in most of the clinical isolates. The expression of cpaf was high in the reference strains compared with the clinical isolates at the mid-phase (6–24 hours post infection) of the developmental cycle. All of the strains had a rather similar tarp expression profile. Four out of five clinical isolates exhibited slower growth kinetics compared with the reference strains. The use of low-passage-number C. trachomatis clinical isolates instead of reference strains in the studies might better reflect the situation in human infection

The Prevalence of HSV, HHV-6, HPV and Mycoplasma genitalium in Chlamydia trachomatis positive and Chlamydia trachomatis Negative Urogenital Samples among Young Women in Finland

Chlamydia trachomatis, Mycoplasma genitalium, herpes simplex virus (HSV) and human papillomavirus (HPV) cause sexually transmitted infections. In addition, human herpesvirus 6 (HHV-6) may be a genital co-pathogen. The prevalence rates of HSV, HHV-6, HPV, M. genitalium, and the C. trachomatis ompA genotypes were investigated by PCR in urogenital samples of the C. trachomatis nucleic acid amplification test positive (n = 157) and age-, community- and time-matched negative (n = 157) women. The prevalence of HPV DNA was significantly higher among the C. trachomatis positives than the C. trachomatis negatives (66% vs. 25%, p <0.001). The prevalence of HSV (1.9% vs. 0%), HHV-6 (11% vs. 14%), and M. genitalium DNA (4.5% vs. 1.9%) was not significantly different between the C. trachomatis-positive and -negative women. Thirteen per cent of test-of-cure specimens tested positive for C. trachomatis. The prevalence of HSV, HHV-6, HPV, M. genitalium, and the C. trachomatis ompA genotypes did not significantly differ between those who cleared the C. trachomatis infection (n = 105) and those who did not (n = 16). The higher prevalence of HPV DNA among the C. trachomatis positives suggests greater sexual activity and increased risk for sexually transmitted pathogens.Peer reviewe

The Prevalence of HSV, HHV-6, HPV and Mycoplasma genitalium in Chlamydia trachomatis positive and Chlamydia trachomatis Negative Urogenital Samples among Young Women in Finland

Chlamydia trachomatis, Mycoplasma genitalium, herpes simplex virus (HSV) and human papillomavirus (HPV) cause sexually transmitted infections. In addition, human herpesvirus 6 (HHV-6) may be a genital co-pathogen. The prevalence rates of HSV, HHV-6, HPV, M. genitalium, and the C. trachomatis ompA genotypes were investigated by PCR in urogenital samples of the C. trachomatis nucleic acid amplification test positive (n = 157) and age-, community- and time-matched negative (n = 157) women. The prevalence of HPV DNA was significantly higher among the C. trachomatis positives than the C. trachomatis negatives (66% vs. 25%, p < 0.001). The prevalence of HSV (1.9% vs. 0%), HHV-6 (11% vs. 14%), and M. genitalium DNA (4.5% vs. 1.9%) was not significantly different between the C. trachomatis-positive and -negative women. Thirteen per cent of test-of-cure specimens tested positive for C. trachomatis. The prevalence of HSV, HHV-6, HPV, M. genitalium, and the C. trachomatis ompA genotypes did not significantly differ between those who cleared the C. trachomatis infection (n = 105) and those who did not (n = 16). The higher prevalence of HPV DNA among the C. trachomatis positives suggests greater sexual activity and increased risk for sexually transmitted pathogens

Transcriptional Expression of the ompA, cpaf, tarp, and tox Genes of Chlamydia trachomatis Clinical Isolates at Different Stages of the Developmental Cycle

The transcriptional gene expression patterns of Chlamydia trachomatis have mainly been studied using reference strains propagated in cultured cells. Here, using five low-passage-number C. trachomatis clinical isolates that originated from asymptomatic or symptomatic female patients, the in vitro expression of the ompA, cpaf, tarp, and tox genes was studied with reverse transcriptase real-time PCR during the chlamydial developmental cycle. We observed dissimilarities in the gene expression patterns between the low-passage-number clinical isolates and the reference strains. The expression of ompA and the peak of the tox expression were observed earlier in the reference strains than in most of the clinical isolates. The expression of cpaf was high in the reference strains compared with the clinical isolates at the mid-phase (6–24 hours post infection) of the developmental cycle. All of the strains had a rather similar tarp expression profile. Four out of five clinical isolates exhibited slower growth kinetics compared with the reference strains. The use of low-passage-number C. trachomatis clinical isolates instead of reference strains in the studies might better reflect the situation in human infection

The Prevalence of HSV, HHV-6, HPV and Mycoplasma genitalium in Chlamydia trachomatis positive and Chlamydia trachomatis Negative Urogenital Samples among Young Women in Finland

Chlamydia trachomatis, Mycoplasma genitalium, herpes simplex virus (HSV) and human papillomavirus (HPV) cause sexually transmitted infections. In addition, human herpesvirus 6 (HHV-6) may be a genital co-pathogen. The prevalence rates of HSV, HHV-6, HPV, M. genitalium, and the C. trachomatis ompA genotypes were investigated by PCR in urogenital samples of the C. trachomatis nucleic acid amplification test positive (n = 157) and age-, community- and time-matched negative (n = 157) women. The prevalence of HPV DNA was significantly higher among the C. trachomatis positives than the C. trachomatis negatives (66% vs. 25%, p < 0.001). The prevalence of HSV (1.9% vs. 0%), HHV-6 (11% vs. 14%), and M. genitalium DNA (4.5% vs. 1.9%) was not significantly different between the C. trachomatis-positive and -negative women. Thirteen per cent of test-of-cure specimens tested positive for C. trachomatis. The prevalence of HSV, HHV-6, HPV, M. genitalium, and the C. trachomatis ompA genotypes did not significantly differ between those who cleared the C. trachomatis infection (n = 105) and those who did not (n = 16). The higher prevalence of HPV DNA among the C. trachomatis positives suggests greater sexual activity and increased risk for sexually transmitted pathogens

Parachlamydia acanthamoebae Detected during a Pneumonia Outbreak in Southeastern Finland, in 2017–2018

Community-acquired pneumonia (CAP) is a common disease responsible for significant morbidity and mortality. However, the definite etiology of CAP often remains unresolved, suggesting that unknown agents of pneumonia remain to be identified. The recently discovered members of the order Chlamydiales, Chlamydia-related bacteria (CRB), are considered as possible emerging agents of CAP. Parachlamydia acanthamoebae is the most studied candidate. It survives and replicates inside free-living amoeba, which it might potentially use as a vehicle to infect animals and humans. A Mycoplasma pneumoniae outbreak was observed in Kymenlaakso region in Southeastern Finland during August 2017–January 2018. We determined the occurrence of Chlamydiales bacteria and their natural host, free-living amoeba in respiratory specimens collected during this outbreak with molecular methods. Altogether, 22/278 (7.9%) of the samples contained Chlamydiales DNA. By sequence analysis, majority of the CRBs detected were members of the Parachlamydiaceae family. Amoebal DNA was not detected within the sample material. Our study further proposes that Parachlamydiaceae could be a potential agent causing atypical CAP in children and adolescents