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Biomedical subjects

D W G Brown

Publications and source records attributed to D W G Brown.

At least 19 recordsLinked to original sources
PubMed2004

A chimeric bovine enteric calicivirus: evidence for genomic recombination in genogroup III of the Norovirus genus of the Caliciviridae.

The Norovirus genus of the Caliciviridae encompasses viruses that cause outbreaks of gastroenteritis in human and viruses that have been associated with diarrhea in cattle. The two bovine noroviruses, Bo/Newbury2/76/UK and Bo/Jena/80/DE, represent two distinct genetic clusters in the newly described genogroup III. In the present study, Jena-like polymerase sequences were identified for the first time in the UK, but one of these, Bo/Thirsk10/00/UK, was a chimeric virus. Bo/Thirsk10/00/UK had a Jena-like polymerase gene but Newbury2-like capsid and ORF3 genes by comparison of their genome organization, nucleotide, and amino acid identities and phylogenetic analyses. The present study is one of few studies to clearly demonstrate the existence of chimeric genomes in the Norovirus genus and the first, to our knowledge, to identify a chimeric genome in genogroup III. It provides additional support that genomic recombination is part of the natural evolution of noroviruses and is relevant to the diagnosis and immunological control of norovirus diarrhea outbreaks.

Amino Acid Sequence↗
PubMed2004

A population-based seroprevalence study of hepatitis A virus using oral fluid in England and Wales.

Population-based seroprevalence studies provide important data on susceptible groups and the potential for future outbreaks. However, the invasive nature of serum collection has limited studies. This paper describes the first postal population-based survey using noninvasive oral fluid technology to collect antibody prevalence data in conjunction with extensive risk factor data to assess the distribution of immunity to common viral infections in England and Wales. These results pertain to hepatitis A virus (HAV). Approximately 5,500 oral fluid samples were collected between August 2001 and May 2002, as well as individual risk factor data through a questionnaire, from persons aged less than 45 years randomly sampled from general practices countrywide. Samples were tested for immunoglobulin G-specific antibody marking a past infection or immunity to HAV using an antibody-capture enzyme-linked immunosorbent assay. The age-specific HAV seroprevalences indicated a low incidence of infection (overall seroprevalence of 18.9% (95% confidence interval: 17.0, 20.9) and of 9.2% (95% confidence interval: 7.1, 11.3) after the exclusion of vaccinees). Vaccination proved the most important determinant of seropositivity. Ethnic minority groups were underrepresented, and adjustment increased the overall prevalence to 20.1% and to 12.1% in unvaccinated individuals. The availability of comprehensive risk factor data allowed the description of two risk profiles related to natural infection and vaccination.

Adolescent↗
PubMed2004

Rubella.

Maternal rubella is now rare in many developed countries that have rubella vaccination programmes. However, in many developing countries congenital rubella syndrome (CRS) remains a major cause of developmental anomalies, particularly blindness and deafness. WHO have provided recommendations for prevention of CRS, and, encouragingly, the number of countries introducing rubella vaccination programmes has risen. However, declining uptake rates due to concerns about the measles-mumps-rubella vaccine in the UK, and increasing numbers of cases in some European countries coupled with poor uptake rates might jeopardise this progress. Surveillance of postnatally and congenitally acquired infection is an essential component of CRS prevention since rubella is difficult to diagnose on clinical grounds alone. Laboratory differentiation of rubella from other rash-causing infections, such as measles, parvovirus B19, human herpesvirus 6, and enteroviruses in developed countries, and various endemic arboviruses is essential. Reverse transcriptase PCR and sequencing for diagnosis and molecular epidemiological investigation and detection of rubella-specific IgG and IgM salivary antibody responses in oral fluid are now available.

Developing Countries↗
PubMed2004

Noroviruses associated with acute gastroenteritis in a children's day care facility in Rio de Janeiro, Brazil.

Noroviruses (Norwalk-like viruses) are an important cause of gastroenteritis worldwide. They are the most common cause of outbreaks of gastroenteritis in the adult population and occur in nursing homes for the elderly, geriatric wards, medical wards, and in hotel and restaurant settings. Food-borne outbreaks have also occurred following consumption of contaminated oysters. This study describes the application of a reverse transcription-polymerase chain reaction (RT-PCR) assay using random primers (PdN6) and specific Ni and E3 primers, directed at a small region of the RNA-dependent RNA polymerase-coding region of the norovirus genome, and DNA sequencing for the detection and preliminary characterisation of noroviruses in outbreaks of gastroenteritis in children in Brazil. The outbreak samples were collected from children <5 years of age at the Bertha Lutz children's day care facility at Oswaldo Cruz Foundation (Fiocruz), Rio de Janeiro, that occurred between 1996 and 1998, where no pathogen had been identified. At the Bertha Lutz day care center facility, only Fiocruz's employee children are provided for, and they come from different social, economic and cultural backgrounds. Three distinct genogroup II strains were detected in three outbreaks in 1997/98 and were most closely related to genotypes GII-3 (Mexico virus) and GII-4 (Grimsby virus), both of which have been detected in paediatric and adult outbreaks of gastroenteritis worldwide.

Acute Disease↗
PubMed2004

A novel method of oral fluid collection to monitor immunity to common viral infections.

Serological surveys among representative population samples have proved rare given their reliance on invasive sample collection. We therefore completed the first population-based postal survey of immunity in England and Wales using new oral fluid technology. This paper examines the feasibility of this new methodological approach. Nearly 5500 oral fluid samples were collected, with individual demographic and social data via a questionnaire, from persons under 45 years of age recruited through general practices. Instructions were accurately followed with only 1% of samples returned without risk-factor data. The overall response rate was 40%. Response was independently associated with age, sex and location. Response was highest in children aged 5-14 years, adult females and in rural locations. This approach allowed the successful collection of comprehensive individual risk data, but response rates in adults must be improved if oral fluid surveys are to routinely complement serological surveillance.

Adolescent↗
PubMed2003

Validation of a modified commercial assay for the detection of rubella-specific IgG in oral fluid for use in population studies.

Matching serum and oral fluid (saliva) samples were collected from 369 subjects in Tunisia in 2002, from a city in the north and a rural district in the south. Rubella-specific IgG was detected in sera by commercial ELISA (Dade Behring) and in matching oral fluids by two methods, a previously described IgG-capture ELISA (GACELISA) [J. Clin. Microbiol. 37 (1999) 391] and the Dade Behring ELISA with the assay protocol modified for use with oral fluids. Total IgG concentration of oral fluids was also measured. Rubella-specific IgG was detected in 289 (78.3%) sera overall. Differences in the age distribution of the study population in the north and south led to a higher prevalence being found in the north (86.2%) than in the south (71.8%). This difference was reflected in the oral fluid rubella-specific IgG results. With GACELISA, rubella-specific IgG was detected in 79.4% of oral fluids from the north and 69.7% from the south and with the modified Dade Behring assay, in 81.4% of oral fluids from the north and in 64.9% from the south. The sensitivity and specificity of GACELISA in comparison to results from the matching sera were 92.4 and 93.2%, respectively. The sensitivity and specificity of the modified Dade Behring ELISA were 89.8 and 92.0%, respectively. Total IgG concentration in oral fluid showed a weak correlation (r=0.19) with the modified Dade Behring results and with samples where total IgG was >7.5 mg/l, the sensitivity and specificity were 94.4 and 90.0%, respectively. Twenty-nine oral fluids, which gave false negative rubella-specific IgG results with the modified Dade Behring ELISA, had a lower mean total IgG concentration than 256 oral fluids which gave concordant positive results (7.0mg/l versus 15.8 mg/l, P<0.001). The study validated the modified Dade Behring ELISA, providing an alternative to the GACELISA for assessing levels of rubella immunity for population studies using oral fluid samples.

Adolescent↗
PubMed2003

Evaluation of a commercial ELISA for detecting Norwalk-like virus antigen in faeces.

A commercially available enzyme immunoassay, the IDEIA Norwalk-like virus (NLV) enzyme linked immunosorbent assay (ELISA; Dako Cytomation, Ely, UK) for detecting NLV antigen in faecal samples and determining the NLV genogroup was evaluated. The performance of the ELISA was compared with that of electron microscopy and the reverse transcription polymerase chain reaction by testing a panel of faecal samples collected from patients involved in outbreaks of gastroenteritis. When compared with reverse transcription-polymerase chain reaction (RT-PCR), the ELISA had a sensitivity and specificity of 55.5 and 98.3%, respectively. This compares with a sensitivity and specificity for EM of 23.9 and 99.2%, respectively. The sensitivity and specificity of the ELISA for determining the aetiology of a Norwalk virus-like outbreak, based on two or more positive samples within an outbreak, were 52.2 and 100% when two samples were collected from an outbreak and 71.4 and 100% when six or more samples were collected. The ELISA correctly identified the NLV genogroups of viruses previously characterised by partial DNA sequencing. The ELISA is a suitable alternative to the preliminary screening by EM for investigating outbreaks of gastroenteritis. Outbreaks, negative by ELISA should be examined by RT-PCR in order to detect strains non-reactive in the assay and virus strains from representative ELISA positive outbreaks should be characterised fully to allow the genetic diversity of NLVs co-circulating in the population to be described.

Antigens, Viral↗
PubMed2003

Primary human herpesvirus-6 and -7 infections, often coinciding, misdiagnosed as measles in children from a tropical region of Brazil.

We investigated primary human herpesvirus-6 and -7 (HHV-6, HHV-7) infections as a cause of rashes incorrectly diagnosed as measles in Brazilian children. Sera from 124 patients, aged 4 months to 17 years, from the states of Rio de Janeiro and Espirito Santo, in whom measles, rubella and parvovirus B19 infections had been excluded, were studied using indirect immunofluorescence antibody avidity tests; 38 (31%) had evidence of primary HHV-6 and/or HHV-7 infections. Twenty four children had primary HHV-6 infection, either recent or coincident with the rash, and similarly 31 had primary HHV-7 infection. Remarkably, almost half (17) of primary infections were dual HHV-6 and HHV-7 infections with the majority, 12 (71%), in children less than 1 year old. HHV-7 infection occurred earlier than previously reported, perhaps due to socioeconomic and tropical conditions in this region of Brazil, and thus coincided with the HHV-6 infections. This study also highlights the difficulties of diagnosing a rash illness on clinical grounds alone.

Adolescent↗
PubMed2003

Herpes simplex virus type 2 and heterosexual spread of human immunodeficiency virus infection in developing countries: hypotheses and research priorities.

Herpes simplex virus type 2 (HSV-2) infection is almost always sexually transmitted, and causes genital ulceration. Significant progress in our understanding of HSV infection has occurred over the last decade, in part related to the development of accurate and sensitive laboratory tests to study HSV-2. The application of PCR and type-specific serology to individual cases and in population-based studies has enabled the identification of a potentially important role for HSV-2 infection as a cofactor in the sexual transmission of HIV. This is a particular issue in developing countries. This review describes the epidemiology of HSV-2 infection in the HIV era, the hypotheses regarding HSV-HIV interactions, and research priorities for the developing world.

Developing Countries↗
PubMed2003

Detection of low-avidity immunoglobulin G in oral fluid samples: new approach for rubella diagnosis and surveillance.

Low-avidity rubella immunoglobulin G (IgG) was detected in oral fluid samples from 30 of 32 rubella IgM-positive patients (sensitivity, 94%) and from 4 of 34 IgM-negative patients (specificity, 88%). Measuring IgG avidity in oral fluid samples could improve the reliability of rubella surveillance when the incidence of the disease and the positive predictive value of IgM tests are low.

Antibodies, Viral↗
PubMed2003

Molecular characterization of bovine enteric caliciviruses: a distinct third genogroup of noroviruses (Norwalk-like viruses) unlikely to be of risk to humans.

Bovine enteric caliciviruses (BoCVs) have been classified in the Norovirus (Norwalk-like virus) genus of the Caliciviridae, raising questions about zoonotic transmission and an animal reservoir for the human Norwalk-like viruses (NLVs), an important cause of nonbacterial gastroenteritis in humans. We examined the genetic relationship of human NLVs to BoCVs that were identified by using reverse transcription-PCR with primer pairs originally designed to detect human NLVs. Polymerase, capsid, and open reading frame 3 (ORF3) gene sequence analyses of BoCVs that were identified from 1976 to 2000 from throughout the United Kingdom showed that BoCVs formed a distinct third genogroup of closely related viruses distinct from the human genogroup I and II NLVs. Evidence was not obtained to support the concept that BoCVs are circulating in humans and pose a threat to human health.

Amino Acid Sequence↗
PubMed2003

Predictors of seropositivity to herpes simplex virus type 2 in women.

Five hundred and twenty consecutive women newly attending a genitourinary medicine clinic who participated in a study of sexual behaviour were also tested for type-specific antibody to herpes simplex virus type 2; 135 (26%) were seropositive, of whom only 29 (21.5%) had had clinical evidence of genital herpes. Seropositive women were much more likely to have a past history of genital herpes (odds ratio [OR] 173). They were also more likely to be black non-UK born (OR 14), aged 30 years or over (OR 6), to have had 6-20 sexual partners (OR 3-4), especially from abroad (OR 12), to be unemployed (OR 6) or blue collar workers (OR 4), to have smoked cigarettes (OR 2) and to have practised peno-anal penetration (OR 5). Disease predictors included a past history of pelvic inflammatory disease (OR 63) and bacterial vaginosis (OR 3). Unexpected predictors were only one sexual partner (OR 5) and no non-regular partners (OR 5). Commencing intercourse before 16 years of age showed a protective effect (OR 0.2) and so did use of oral contraception (OR 0.5). Our findings show that infection with HSV-2 is associated with a wider range of morbidity and also emphasize the role of male sexual partner selection in the transmission of infection.

Antibodies, Viral↗
PubMed2002

Oral fluid collection by post--a pilot study of two approaches.

This pilot study aimed to assess the feasibility of the postal collection of oral fluid samples for surveillance purposes and the effect of two different approaches on the response rates. This cross-sectional, antibody prevalence study collected oral fluid samples and questionnaire data from randomly selected individuals, aged under 45 y, through the post. The individuals were recruited from four general practice registers. In a one stage approach patients were sent the oral fluid kit with the initial invitation letter. In a two stage approach the kits were sent out after written consent had been received. There was little difference in the overall response rates between the two approaches (38% two stage and 41% one stage), though the response rate for the one stage approach was 10% higher in the under-20-y-olds in practices from areas of greater deprivation. The low response partly reflected poor uptake in young adults who may need to be approached through more targeted surveys. In the other age groups additional reminders could prove a cost-effective way of increasing the response rate further.

Adolescent↗
PubMed2002

Characterization of measles virus strains causing SSPE: a study of 11 cases.

Eleven subacute sclerosing panencephalitis (SSPE) cases diagnosed in the UK between 1965 and 2000 were investigated. The entire or partial matrix (M), hemagglutinin (H), and nucleoprotein (N) genes of measles virus (MV) were sequenced following direct RT-PCR amplification from brain tissues. All the M genes showed the characteristic biased hypermutations and a premature termination codon was detected in 5/11 M sequences. Based on the more highly conserved H and N genes observed in persistent MV studies, phylogenetic analysis showed that two of three strains from patients likely to have acquired infection in the 1950s were related to clade C (WHO designation) and one appears to be a novel genotype. Three strains from patients infected in the 1960s and 1970s were clearly related to a MV strain isolated in 1974 belonging to genotype D1. Four strains from patients infected in the 1980s clustered with genotype D7 strains. One sequence from a patient infected in 1990s was identified as genotype D6. No vaccine strains were detected although five of these patients had been previously immunized. The sequence data obtained from these historic strains do not support the view that vaccine strains are associated with SSPE and provide valuable information for further studies of MV epidemiology, evolution, and pathogenesis in SSPE.

Adolescent↗
PubMed2002

Generation of recombinant virus-like particles of human and non-human polyomaviruses in yeast Saccharomyces cerevisiae.

OBJECTIVES: Non-viral methods of gene transfer have been preferred in gene therapy approaches for several reasons, particularly for their safety, simplicity and convenience in introducing heterologous DNA into cells. Polyomavirus virus-like particles (VLPs) represent a promising carrier for encapsidation of foreign nucleic acids for gene therapy. For the development of such gene delivery systems as well as for providing reagents for improving virus diagnostics, an efficient yeast expression system for the generation of different polyomavirus VLPs was established. METHODS: A galactose-inducible Saccharomyces cerevisiae yeast expression system was used. Formation of empty VLPs was confirmed by cesium chloride ultracentrifugation, agarose gel electrophoresis and electron microscopy. Cross-reactivity of the major capsid proteins (VP1) of different polyomaviruses was analyzed by Western blot using rabbit and mice sera raised against the VP1 proteins. RESULTS: VP1 of polyomaviruses from humans (JC polyomavirus and serotypes AS and SB of BK polyomavirus), rhesus monkeys (simian virus 40), hamsters (hamster polyomavirus), mice (murine polyomavirus) and birds (budgerigar fledgling disease virus) were expressed at high levels in yeast. Empty VLPs formed by all yeast-expressed VP1 proteins were dissociated into pentamers and reassociated into VLPs by defined ion and pH conditions. Different patterns of cross-reactivity of the VP1 proteins with heterologous mice and rabbit sera were observed. CONCLUSION: The developed heterologous yeast expression system is suitable for high-level production of polyomavirus VLPs. Yeast-derived VLPs are generally free of toxins, host cell DNA and proteins. These VLPs might be useful for the generation of new diagnostical tools, gene delivery systems and antiviral vaccines.

Amino Acid Sequence↗