[Show abstract][Hide abstract] ABSTRACT: B19V is a member of the Parvoviridae family, genus Erythrovirus. B19V IgG and IgM have different reactivities against conformational and linear epitopes of VP1 and VP2 antigens leading to the development of IgM, and IgG-avidity and epitope type specificity (ETS) enzyme immunoassays (EIAs) for identifying recent from past infection. Additionally, B19V viral load determination (qPCR) is increasingly used in staging B19V infection, and in this study the utility of these methods is compared.A panel of 78 sera was jointly tested by the Virus Reference Department (VRD), London, UK and the Haartman Institute (HI), Helsinki, Finland using a number of EIAs eg. B19V-IgG, IgM, IgG-avidity and ETS-EIA. At VRD, the sera were tested, also, by a B19V viral load PCR (qPCR).By consensus analysis, 43 (55.1%) sera represented past infection, 28 (35.9%) sera represented recent infection, and 7 (9.0%) sera were indeterminate. Both VRD B19V qPCR and HI B19V IgM EIA gave the highest agreement with consensus interpretation for past or recent infection with an overall agreement of 99% (95%CI:[92-100]) and positive predictive value (PPV) of 100% (95%CI:[87-100]). Nine sera, designated past infection by consensus analysis were B19V IgM positive by a commercial VRD B19V IgM EIA and B19V IgM negative by a new HI in house B19V IgM EIA. A new VRD IgG-avidity EIA showed good >95% agreement (excluding equivocal results) with consensus interpretations for recent or past infection.Correct identification of recent from past B19V infection was achieved through application of qPCR or by appropriate selection of EIAs.
[Show abstract][Hide abstract] ABSTRACT: Introduction:
In the UK, primary varicella is usually a mild infection in children, but can cause serious illness in susceptible pregnant women and adults. The UK Joint Committee on Vaccination and Immunisation is considering an adolescent varicella vaccination programme. Cost-effectiveness depends upon identifying susceptibles and minimising vaccine wastage, and chickenpox history is one method to screen for eligibility. To inform this approach, we estimated the proportion of adolescents with varicella antibodies by reported chickenpox history.
Recruitment occurred through secondary schools in England from February to September 2012. Parents were asked about their child's history of chickenpox, explicitly setting the context in terms of the implications for vaccination. 247 adolescents, whose parents reported positive (120), negative (77) or uncertain (50) chickenpox history provided oral fluid for varicella zoster virus-specific immunoglobulin-G (VZV-IgG) testing.
109 (90.8% [85.6-96.0%]) adolescents with a positive chickenpox history, 52 (67.5% [57.0-78.1%]) with a negative history and 42 (84.0% [73.7-94.3%]) with an uncertain history had VZV-IgG suggesting prior infection. Combining negative and uncertain histories, 74% had VZV-IgG (best-case). When discounting low total-IgG samples and counting equivocals as positive (worst-case), 84% had VZV-IgG. We also modelled outcomes by varying the negative predictive value (NPV) for the antibody assay, and found 74-87% under the best-case and 84-92% under the worst-case scenario would receive vaccine unnecessarily as NPV falls to 50%.
Reported chickenpox history discriminates between varicella immunity and susceptibility in adolescents, but significant vaccine wastage would occur if this approach alone were used to determine vaccine eligibility. A small but important proportion of those with positive chickenpox history would remain susceptible. These data are needed to determine whether reported history, with or without oral fluid testing in those with negative and uncertain history, is sufficiently discriminatory to underpin a cost-effective adolescent varicella vaccination programme.
[Show abstract][Hide abstract] ABSTRACT: Background
Human parvovirus 4 (ParV4), a newly described member of the family Parvoviridae, like B19V, has been found in pooled plasma preparations. The extent, and significance, of ParV4 exposure in UK blood donors remain to be determined and reliable detection of ParV4 immunoglobulin (Ig)G, using validated methods, is needed. Study Design and Methods
With ParV4 virus-like particles a ParV4 IgG time-resolved fluorescence immunoassay (TRFIA) was developed. There is no gold standard or reference assay for measuring ParV4 IgG and the utility of the TRFIA was first examined using a panel of sera from people who inject drugs (PWIDS)a high-prevalence population for ParV4 infection. Western blotting was used to confirm the specificity of TRFIA-reactive sera. Two cohorts of UK blood donor sera comprising 452 sera collected in 1999 and 156 sera collected in 2009 were tested for ParV4 IgG. Additional testing for B19V IgG, hepatitisC virus antibodies (anti-HCV), and ParV4 DNA was also undertaken. ResultsThe rate of ParV4 IgG seroprevalence in PWIDS was 20.7% and ParV4 IgG was positively associated with the presence of anti-HCV with 68.4% ParV4 IgG-positive sera testing anti-HCV-positive versus 17.1% ParV4 IgG-negative sera. Overall seropositivity for ParV4 IgG, in 608 UK blood donors was 4.76%. The ParV4 IgG seropositivity for sera collected in 1999 was 5.08%, compared to 3.84% for sera collected in 2009. No ParV4 IgG-positive blood donor sera had detectable ParV4 DNA. Conclusion
ParV4 IgG has been found in UK blood donors and this finding needs further investigation.
[Show abstract][Hide abstract] ABSTRACT: To evaluate the performance of a newly developed point-of-care test (POCT) for the detection of measles-specific IgM antibodies in serum and oral fluid specimens and to assess if measles virus nucleic acid could be recovered from used POCT strips.
The POCT was used to test 170 serum specimens collected through measles surveillance or vaccination programmes in Ethiopia, Malaysia and the Russian Federation: 69 were positive for measles immunoglobulin M (IgM) antibodies, 74 were positive for rubella IgM antibodies and 7 were positive for both. Also tested were 282 oral fluid specimens from the measles, mumps and rubella (MMR) surveillance programme of the United Kingdom of Great Britain and Northern Ireland. The Microimmune measles IgM capture enzyme immunoassay was the gold standard for comparison. A panel of 24 oral fluids was used to investigate if measles virus haemagglutinin (H) and nucleocapsid (N) genes could be amplified by polymerase chain reaction directly from used POCT strips.
With serum POCT showed a sensitivity and specificity of 90.8% (69/76) and 93.6% (88/94), respectively; with oral fluids, sensitivity and specificity were 90.0% (63/70) and 96.2% (200/208), respectively. Both H and N genes were reliably detected in POCT strips and the N genes could be sequenced for genotyping. Measles virus genes could be recovered from POCT strips after storage for 5 weeks at 20-25 °C.
The POCT has the sensitivity and specificity required of a field-based test for measles diagnosis. However, its role in global measles control programmes requires further evaluation.
Bulletin of the World Health Organisation 09/2011; 89(9):675-82. DOI:10.2471/BLT.11.088427 · 5.09 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A new strain of measles virus, D4-Hamburg, was imported from London to Hamburg in December 2008 and subsequently spread to Bulgaria, where an outbreak of >24,300 cases was observed. We analyzed spread of the virus to demonstrate the importance of addressing hard-to-reach communities within the World Health Organization European Region regarding access to medical care and vaccination campaigns. The D4-Hamburg strain appeared during 2009-2011 in Poland, Ireland, Northern Ireland, Austria, Greece, Romania, Turkey, Macedonia, Serbia, Switzerland, and Belgium and was repeatedly reimported to Germany. The strain was present in Europe for >27 months and led to >25,000 cases in 12 countries. Spread of the virus was prevalently but not exclusively associated with travel by persons in the Roma ethnic group; because this travel extends beyond the borders of any European country, measures to prevent the spread of measles should be implemented by the region as a whole.
[Show abstract][Hide abstract] ABSTRACT: In 2002, the World Health Organization (WHO) adopted a goal to eliminate measles in the European Region by 2010. Measles elimination is defined as the interruption of indigenous measles virus (MV) transmission. The molecular epidemiology of MV transmission in the WHO European Region was studied through the investigation of reported cases and outbreaks to monitor the region's progress toward its measles elimination goal.
National and regional laboratories performed molecular characterization of MV detected between 2007 and 2009 in the WHO European Region. To document indigenous transmission and importations into the region, we analyzed genotyping results and epidemiological data on measles outbreaks reported by the member states.
Since 2007, MV genotype D6 has not been reported in the WHO European Region, suggesting that its chains of transmission have been interrupted, whereas several other MV genotypes are still circulating. Although several European countries have already interrupted indigenous MV transmission, genotyping showed that 3 endemic MV transmission chains have been reestablished in other countries.
The WHO European Region 2010 goal will not be met, as indigenous transmission of MV has not been interrupted. As the region begins to document its process of elimination verification to monitor progress toward the goal, countries will need to ensure that genotyping is performed in all measles outbreaks.
The Journal of Infectious Diseases 07/2011; 204 Suppl 1(Supplement 1):S335-42. DOI:10.1093/infdis/jir101 · 6.00 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: An important aspect of laboratory surveillance for measles and rubella is the genetic characterization of circulating wild-type viruses to support molecular epidemiologic studies and to track transmission pathways. Virologic surveillance that is sufficient to document the interruption of transmission of measles and rubella viruses will be an essential criterion for verification of elimination. Laboratories in the World Health Organization (WHO) Measles and Rubella Laboratory Network have worked to improve and expand virologic surveillance as many regions move toward elimination of measles and rubella/congenital rubella syndrome. As countries approach elimination, it will be necessary to obtain genetic information from as many chains of transmission as possible. In addition, baseline virologic surveillance, especially for rubella, needs to be improved in many countries. This report contains a summary of recent improvements to the methods used for virologic surveillance.
The Journal of Infectious Diseases 07/2011; 204 Suppl 1(Supplement 1):S506-13. DOI:10.1093/infdis/jir117 · 6.00 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We analyzed data from hospital admissions and enhanced mumps surveillance to assess mumps complications during the largest mumps outbreak in England and Wales, 2004-2005, and their association with mumps vaccination. When compared with nonoutbreak periods, the outbreak was associated with a clear increase in hospitalized patients with orchitis, meningitis, and pancreatitis. Routine mumps surveillance and hospital data showed that 6.1% of estimated mumps patients were hospitalized, 4.4% had orchitis, 0.35% meningitis, and 0.33% pancreatitis. Enhanced surveillance data showed 2.9% of mumps patients were hospitalized, 6.1% had orchitis, 0.3% had meningitis, and 0.25% had pancreatitis. Risk was reduced for hospitalization (odds ratio [OR] 0.54, 95% confidence interval [CI] 0.43-0.68), mumps orchitis (OR 0.72, 95% CI 0.56-0.93) and mumps meningitis (OR 0.28, 95% CI 0.14-0.56) when patient had received 1 dose of measles, mumps, and rubella vaccine. The protective effect of vaccination on disease severity is critical in assessing the total effects of current and future mumps control strategies.
[Show abstract][Hide abstract] ABSTRACT: Surveillance of rubella in England and Wales has included immunoglobulin M testing of oral (crevicular) fluid from reported case-patients since 1994. The need for laboratory confirmation to monitor rubella elimination is emphasized by poor sensitivity (51%, 95% confidence interval 48.9%-54.0%) and specificity (55%, 95% confidence interval 53.7%-55.6%) of the clinical case definition. During 1999-2008, oral fluid from 11,709 (84%) of 13,952 reported case-patients was tested; 143 (1.0%) cases were confirmed and 11,566 (99%) were discarded (annual investigation and discard rate of clinically suspected rubella cases was 2,208/100,000 population). Incidence of confirmed rubella increased from 0.50 to 0.77/1 million population when oral fluid testing was included. Oral fluid tests confirmed that cases were more likely to be in older, unvaccinated men. Testing of oral fluid has improved ascertainment of confirmed rubella in children and men and provided additional information for assessing UK progress toward the World Health Organization elimination goal.
[Show abstract][Hide abstract] ABSTRACT: Waning immunity to mumps after one or two doses of the measles, mumps and rubella (MMR) vaccine has been described. Using a human peripheral blood lymphocyte (PBL)-severe combined immunodeficiency (SCID) mouse model, MMR vaccine recipients with undetectable and high antibody titres against mumps were compared for the presence of circulating mumps-specific memory B cells. Peripheral blood mononuclear cells (PBMC) from six donors (three subjects with undetectable and three with high antibody titres against mumps) were injected into the spleens of non-obese diabetic (NOD)-SCID mice (three mice per subject). Mice were pretreated with TMbeta1 and total body irradiation to improve engraftment. In vivo production of human antibodies against mumps was evaluated in mouse plasma on days 7, 10 and 13 with a commercial enzyme-linked immunosorbent assay (ELISA), functional reduction neutralization test. Three donors had mumps antibody titres below the detection limit (titre < 230) and three had high antibody titres (range 5700-7300). None of the mice injected with PBMC from subjects with undetectable antibody titres showed detectable human antibody titres, despite the presence of cell-mediated immunity in two of the three donors. Seven out of nine mice injected with PBMC from subjects with high antibody titres acquired detectable antibody titres for mumps in their plasma. PBMC from vaccinees without detectable serum antibodies against mumps virus were unable to induce secretion of anti-mumps antibodies in the blood of recipient mice, whereas PBMC from vaccinees with high antibody titres were able to do so. This observation suggests that the frequency of mumps-specific memory B cells is very low in vaccinees with undetectable antibody titres. These individuals may therefore be at risk of developing mumps disease upon encounter with wild-type virus.
[Show abstract][Hide abstract] ABSTRACT: The first human parvoviruses to be described (1960s) were the adeno-associated viruses (AAVs, now classed as dependoviruses), originally identified as contaminants of cell cultures, followed by parvovirus B19 (B19V) in 1974, the first parvovirus to be definitively shown to be pathogenic. More recently two new groups of parvoviruses, the human bocaviruses (HuBoV) and the Parv4 viruses have been identified. These four groups of human viruses are all members of different genera within the Parvovirus family, and have very different biology, epidemiology and disease associations from each other. This review will provide an overview of the virological, pathogenic and clinical features of the different human paroviruses, and how these new viruses and their variants fit into the current understanding of parvovirus infection.
Reviews in Medical Virology 07/2010; 20(4):231-44. DOI:10.1002/rmv.648 · 5.57 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To determine the origin of the virus associated with a measles outbreak in Menglian County, Yunnan Province, People's Republic of China, in 2009, we conducted genetic analyses. Phylogenetic analyses based on nucleoprotein (N) and hemagglutinin (H) gene sequences showed that these Menglian viruses were not closely related to sequences of any World Health Organization (WHO) reference strains representing the 23 currently recognized genotypes. The minimum nucleotide divergence between the Menglian viruses and the most closely related reference strain, genotype D7, was 3.3% for the N gene and 3.0% for the H gene. A search of the databases of GenBank, WHO, and the Health Protection Agency Measles Nucleotide Surveillance showed that the Menglian viruses, together with the 2 older non-Menglian viruses, could be members of a new proposed measles genotype, d11. The new genotype designation will allow for better description of measles transmission patterns, especially in the Southeast Asian and Western Pacific regions.
[Show abstract][Hide abstract] ABSTRACT: Although the plaque reduction neutralization test (PRNT) is considered the "gold-standard" assay for measuring neutralizing antibodies for mumps, it is technically demanding, slow and requires large serum volumes, which limits its use for investigating mumps vaccine efficacy and population susceptibility. Therefore, an immunocolourimetric-based focus reduction neutralization test (FRNT) was developed and validated against PRNT using 30 blood donor plasma samples (16 positive, 5 equivocal, and 9 negative for mumps IgG by EIA). The samples were tested in triplicate by FRNT and PRNT in 10 and 4 separate assay runs, respectively, and 50% neutralizing antibody titres calculated using the Kärber formula. There was good correlation between the two neutralization assays (R(2)=0.88). Inter-assay variation for FRNT titres was 2-fold, compared to a 3-fold variation for PRNT titres. From the distribution of results, a positive cut-off for FRNT was defined as 1:4. In conclusion, FRNT has similar sensitivity to the PRNT and offers the advantage of speed (2 days vs. 7 days), reduced sample volume (40 microL vs. 150 microL), and the possibility of automation using 96-well plates. FRNT appears to be a good substitute for PRNT for characterising the immune response to mumps and for vaccine efficacy studies.
[Show abstract][Hide abstract] ABSTRACT: Three full-length genomic clones (pB19-M20, pB19-FL and pB19-HG1) of parvovirus B19 were produced in different laboratories. pB19-M20 was shown to produce infectious virus. To determine the differences in infectivity, all three plasmids were tested by transfection and infection assays. All three clones were similar in viral DNA replication, RNA transcription, and viral capsid protein production. However, only pB19-M20 and pB19-HG1 produced infectious virus. Comparison of viral sequences showed no significant differences in ITR or NS regions. In the capsid region, there was a nucleotide sequence difference conferring an amino acid substitution (E176K) in the phospholipase A2-like motif of the VP1-unique (VP1u) region. The recombinant VP1u with the E176K mutation had no catalytic activity as compared with the wild-type. When this mutation was introduced into pB19-M20, infectivity was significantly attenuated, confirming the critical role of this motif. Investigation of the original serum from which pB19-FL was cloned confirmed that the phospholipase mutation was present in the native B19 virus.
[Show abstract][Hide abstract] ABSTRACT: The pathogenic parvovirus B19 (B19V) has an extreme tropism for human erythroid progenitor cells. In vitro, only a few erythroid leukemic cell lines (JK-1 and KU812Ep6) or megakaryoblastoid cell lines (UT7/Epo and UT7/Epo-S1) with erythroid characteristics support B19V replication, but these cells are only semipermissive. By using recent advances in generating large numbers of human erythroid progenitor cells (EPCs) ex vivo from hematopoietic stem cells (HSCs), we produced a pure population of CD36(+) EPCs expanded and differentiated from CD34(+) HSCs and assessed the CD36(+) EPCs for their permissiveness to B19V infection. Over more than 3 weeks, cells grown in serum-free medium expanded more than 800,000-fold, and 87 to 96% of the CD36(+) EPCs were positive for globoside, the cellular receptor for B19V. Immunofluorescence (IF) staining showed that about 77% of the CD36(+) EPCs were positive for B19V infection, while about 9% of UT7/Epo-S1 cells were B19V positive. Viral DNA detected by real-time PCR increased by more than 3 logs in CD36(+) EPCs; the increase was 1 log in UT7/Epo-S1 cells. Due to the extensive permissivity of CD36(+) EPCs, we significantly improved the sensitivity of detection of infectious B19V by real-time reverse transcription-PCR and IF staining 100- and 1,000-fold, respectively, which is greater than the sensitivity of UT7/Epo-S1 cell-based methods. This is the first description of an ex vivo method to produce large numbers of EPCs that are highly permissive to B19V infection and replication, offering a cellular system that mimics in vivo infection with this pathogenic human virus.
Journal of Virology 04/2008; 82(5):2470-6. DOI:10.1128/JVI.02247-07 · 4.44 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: During 2005-2006, nine measles virus (MV) genotypes were identified throughout the World Health Organization European Region. All major epidemics were associated with genotypes D4, D6, and B3. Other genotypes (B2, D5, D8, D9, G2, and H1) were only found in limited numbers of cases after importation from other continents. The genetic diversity of endemic D6 strains was low; genotypes C2 and D7, circulating in Europe until recent years, were no longer identified. The transmission chains of several indigenous MV strains may thus have been interrupted by enhanced vaccination. However, multiple importations from Africa and Asia and virus introduction into highly mobile and unvaccinated communities caused a massive spread of D4 and B3 strains throughout much of the region. Thus, despite the reduction of endemic MV circulation, importation of MV from other continents caused prolonged circulation and large outbreaks after their introduction into unvaccinated and highly mobile communities.
[Show abstract][Hide abstract] ABSTRACT: A real-time PCR assay for measles virus was designed and validated using clinical samples including oral fluids, sera, urines, throat swabs, blood samples, and nasopharyngeal aspirates. The test was specific for measles virus, with a slightly higher sensitivity compared to the conventional nested PCR. Calculation of viral genome number in these samples, by comparison with a standard curve prepared from dilutions of cloned measles virus H gene, indicated that, overall, serum samples tended to have a lower viral load than oral fluid samples, and that the viral load decreased with increasing time after onset of symptoms. The real-time PCR is considered to be a sensitive and specific alternative to the conventional measles PCR, especially in situations where early and rapid diagnosis are important.
Journal of Medical Virology 10/2007; 79(10):1587-92. DOI:10.1002/jmv.20997 · 2.35 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In an attempt to experimentally define the roles of viral proteins encoded by the B19 genome in the viral life cycle, we utilized the B19 infectious clone constructed in our previous study to create two groups of B19 mutant genomes: (i) null mutants, in which either a translational initiation codon for each of these viral genes was substituted by a translational termination codon or a termination codon was inserted into the open reading frame by a frameshift; and (ii) a deletion mutant, in which half of the hairpin sequence was deleted at both the 5' and the 3' termini. The impact of these mutations on viral infectivity, DNA replication, capsid protein production, and distribution was systematically examined. Null mutants of the NS and VP1 proteins or deletion of the terminal hairpin sequence completely abolished the viral infectivity, whereas blocking expression of the 7.5-kDa protein or the putative protein X had no effect on infectivity in vitro. Blocking expression of the proline-rich 11-kDa protein significantly reduced B19 viral infectivity, and protein studies suggested that the expression of the 11-kDa protein was critical for VP2 capsid production and trafficking in infected cells. These findings suggest a previously unrecognized role for the 11-kDa protein, and together the results enhance our understanding of the key features of the B19 viral genome and proteins.
Journal of Virology 07/2006; 80(12):5941-50. DOI:10.1128/JVI.02430-05 · 4.44 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Parvovirus B19, the only known pathogenic human parvovirus is the aetiologic agent of erythema infectiosum, transient aplastic crisis, pure red cell aplasia, and hydrops fetalis. Transmission is either by respiratory secretions or, as it can be present at high titre in plasma, by blood and blood products. B19 is only cultured with difficulty in vitro, and there is no readily available assay for detecting B19 infectivity or neutralizing antibodies.
In this study, we evaluated different methods to detect viral infection for the purpose of developing automated methods for large-scale testing of viral infectivity, development of neutralizing antibody and viral inactivation assays.
Different cell lines were evaluated for their ability to support B19 infection and assays tested for sensitivity and ease of performing. A high-throughput assay was validated by determining infectious virus in blood pools and for determining neutralizing antibody in sera.
B19 protein production was detected by immunofluorescence (IF) staining and increased viral DNA production by dot blot hybridization and quantitative PCR. The detection of RNA transcripts by RT-PCR assay and quantitative RT-PCR (qRT-PCR) was used as an indirect marker for infection. Of the cell lines tested, the subclone UT7/Epo-S1 showed the greatest sensitivity to B19 infection, with detection of viral transcripts by qRT-PCR the preferred assay. The assays were validated by experiments to determine the infectious titre of sera from acutely infected humans, to evaluate the presence of infectious virus in human donor plasma pools and to measure neutralizing antibodies.