| 1. |
- Ayukekbong, James, et al.
(författare)
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Pattern of Circulation of Norovirus GII Strains during Natural Infection
- 2014
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Ingår i: Journal of Clinical Microbiology. - : American Society for Microbiology. - 0095-1137 .- 1098-660X. ; 52:12, s. 4253-4259
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Tidskriftsartikel (refereegranskat)abstract
- Norovirus (NoV) is considered a major cause of nonbacterial gastroenteritis among people of all ages worldwide, but the natural course of infection is incompletely known. In this study, the pattern of circulation of NoVs was studied among 146 children and 137 adults in a small community in southwestern Cameroon. The participants provided monthly fecal samples during a year. NoV RNA was detected in at least one sample from 82 (29%) of the participants. The partial VP1 region could be sequenced in 36 NoV GII-positive samples. Three different genotypes were identified (GII.1, GII.4, and GII.17), with each genotype circulating within 2 to 3 months and reappearing after a relapse period of 2 to 3 months. Most infections occurred once, and 2 episodes at most within a year were detected. No difference in the frequency of NoV infection between children and adults was recorded. The same genotype was detected for a maximum of 2 consecutive months in 3 children only, suggesting that a less than 30-day duration of viral shedding in natural infection was common. Reinfection within a year with the same genotype was not observed, consistent with short-term homotypic immune protection. The study revealed that NoV strains are circulating with a limited duration of viral shedding both in the individuals and the population as part of their natural infection. The results also provide evidence of cross-protective immunity of limited duration between genotypes of the same genogroup.
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| 2. |
- Belak, Sandor
(författare)
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Rapid PCR-Based Molecular Pathotyping of H5 and H7 Avian Influenza Viruses
- 2011
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Ingår i: Journal of Clinical Microbiology. - 0095-1137 .- 1098-660X. ; 49, s. 3860-3873
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Tidskriftsartikel (refereegranskat)abstract
- While the majority of avian influenza virus (AIV) subtypes are classified as low-pathogenicity avian influenza viruses (LPAIV), the H5 and H7 subtypes have the ability to mutate to highly pathogenic avian influenza viruses (HPAIV) in poultry and therefore are the etiological agents of notifiable AIV (NAIV). It is of great importance to distinguish HPAIV from LPAIV variants during H5/H7 outbreaks and surveillance. To this end, a novel and fast strategy for the molecular pathotyping of H5/H7 AIVs is presented. The differentiation of the characteristic hemagglutinin (HA) protein cleavage sites (CSs) of HPAIVs and LPAIVs is achieved by a novel PCR method where the samples are interrogated for all existing CSs with a 484-plex primer mixture directly targeting the CS region. CSs characteristic for HP or LP H5/H7 viruses are distinguished in a seminested duplex real-time PCR format using plexor fluorogenic primers. Eighty-six laboratory isolates and 60 characterized NAIV-positive clinical specimens from poultry infected with H5/H7 both experimentally and in the field were successfully pathotyped in the validation. The method has the potential to substitute CS sequencing in the HA gene for the determination of the molecular pathotype, thereby providing a rapid means to acquire additional information concerning NAIV outbreaks, which may be critical to their management. The new assay may be extended to the LP/HP differentiation of previously unknown H5/H7 isolates. It may be considered for integration into surveillance and control programs in both domestic and wild bird populations.
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| 3. |
- Blomström, Anne-Lie, et al.
(författare)
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Detection of a Novel Astrovirus in Brain Tissue of Mink Suffering from Shaking Mink Syndrome by Use of Viral Metagenomics
- 2010
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Ingår i: Journal of Clinical Microbiology. - 0095-1137 .- 1098-660X. ; 48, s. 4392-4396
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Tidskriftsartikel (refereegranskat)abstract
- In 2000, farmed mink kits in Denmark were affected by a neurological disorder. The characteristic clinical signs included shaking, staggering gait, and ataxia. The disease, given the name shaking mink syndrome, was reproduced by the inoculation of brain homogenate from affected mink kits into healthy ones. However, the etiology remained unknown despite intensive efforts. In this study, random amplification and large-scale sequencing were used, and an astrovirus was detected in the brain tissue of three experimentally infected mink kits. This virus also was found in the brain of three mink kits naturally displaying the disease but not in the six healthy animals investigated. The complete coding region of the detected astrovirus was sequenced and compared to those of both a mink astrovirus associated with preweaning diarrhea and to a recently discovered human astrovirus associated with a case of encephalitis in a boy with x-linked agammaglobulinemia. The identities were 80.4 and 52.3%, respectively, showing that the virus described in this study was more similar to the preweaning diarrhea mink astrovirus. For the nonstructural coding regions the sequence identity was around 90% compared to that of the astrovirus, which is associated with preweaning diarrhea in mink. The region coding for the structural protein was more diverse, showing only 67% sequence identity. This finding is of interest not only because the detected virus may be the etiological agent of the shaking mink syndrome but also because this is one of the first descriptions of an astrovirus found in the central nervous system of animals.
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| 4. |
- Bom, Reinier J. M., et al.
(författare)
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Evaluation of High-Resolution Typing Methods for Chlamydia trachomatis in Samples from Heterosexual Couples
- 2011
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Ingår i: Journal of Clinical Microbiology. - 0095-1137 .- 1098-660X. ; 49:8, s. 2844-2853
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Tidskriftsartikel (refereegranskat)abstract
- We aimed to compare conventional ompA typing of Chlamydia trachomatis with multilocus sequence typing (MLST) and multilocus variable-number tandem-repeat (VNTR) analysis (MLVA). Previously used MLST and MLVA systems were compared to modified versions that used shorter target regions and nested PCR. Heterosexual couples were selected from among persons with urogenital C. trachomatis infections visiting the sexually transmitted infection outpatient clinic in Amsterdam, The Netherlands. We identified 30 couples with a total of 65 degrees C. trachomatis-positive samples on which MLST and MLVA for eight target regions were performed. All regions were successfully sequenced in 52 samples, resulting in a complete profile for 18 couples and 12 individuals. Nine ompA genovars from D to K, with two variants of genovar G, were found. The numbers of sequence type and MLVA type profiles were 20 for MLST and 21 for MLVA, and a combination of MLST and MLVA yielded 28 profiles, with discriminatory indexes (D) ranging from 0.95 to 0.99. Partners in 17 couples shared identical profiles, while partners in 1 couple had completely different profiles. Three persons had infections at multiple anatomical locations, and within each of these three individuals, all profiles were identical. The discriminatory capacity of all MLST and MLVA methods is much higher than that of ompA genotyping (D = 0.78). No genotype variation was found within the samples of the same person or from heterosexual couples with a putative single transmission. This shows that the chlamydial genome in clinical specimens has an appropriate polymorphism to enable epidemiological cluster analysis using MLST and MLVA.
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| 5. |
- Bongcam Rudloff, Erik, et al.
(författare)
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Molecular Typing of Escherichia coli O157:H7 Isolates from Swedish Cattle and Human Cases: Population Dynamics and Virulence
- 2014
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Ingår i: Journal of Clinical Microbiology. - 0095-1137 .- 1098-660X. ; 52, s. 3906-3912
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Tidskriftsartikel (refereegranskat)abstract
- While all verotoxin-producing Escherichia coli O157:H7 bacteria are considered potential pathogens, their genetic subtypes appear to differ in their levels of virulence. The aim of this study was to compare the distribution of subtypes of E. coli O157:H7 in the cattle reservoir and in human cases with and without severe complications in order to gain clues about the relationship between subtype and relative virulence. A lineage-specific polymorphism assay (LSPA-6), multilocus variable-number tandem-repeat analysis (MLVA), and a novel real-time PCR assay to identify clade 8 were applied to a large and representative set of isolates from cattle from 1996 to 2009 (n = 381) and human cases from 2008 to 2011 (n = 197) in Sweden. Draft genome sequences were produced for four selected isolates. The E. coli O157:H7 isolates in Swedish cattle generally belonged to four groups with the LSPA-6 profiles 211111 (clade 8/non-clade 8), 213111, and 223323. The subtype composition of the cattle isolates changed dramatically during the study period with the introduction and rapid spread of the low-virulence 223323 subtype. The human cases presumed to have been infected within the country predominantly carried isolates with the profiles 211111 (clade 8) and 213111. Cases progressing to hemolytic-uremic syndrome (HUS) were mostly caused by clade 8, with MLVA profiles consistent with Swedish cattle as the source. In contrast, infections contracted abroad were caused by diverse subtypes, some of which were associated with a particular region. The work presented here confirms the high risk posed by the clade 8 variant of E. coli O157:H7. It also highlights the dynamic nature of the E. coli O157:H7 subtype composition in animal reservoirs and the importance of this composition for the human burden of disease.
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| 6. |
- Christerson, Linus, et al.
(författare)
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Chlamydia trachomatis Strains Show Specific Clustering for Men Who Have Sex with Men Compared to Heterosexual Populations in Sweden, the Netherlands, and the United States
- 2012
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Ingår i: Journal of Clinical Microbiology. - 0095-1137 .- 1098-660X. ; 50:11, s. 3548-3555
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Tidskriftsartikel (refereegranskat)abstract
- High-resolution genotyping of Chlamydia trachomatis improves the characterization of strains infecting different patient groups and sexual networks. In this study, multilocus sequence typing (MLST) and ompA sequence determination were used for an analysis of C. trachomatis strains from 203 men who have sex with men (MSM) from Sweden, the Netherlands, and the United States. The results obtained were compared with data from 153 heterosexual women from Sweden and the Netherlands. The overlap in MLST/ompA profiles between MSM from Sweden and the Netherlands was 68%, while the overlap between heterosexual populations from these countries was only 18%. The distribution of genotypes in MSM from the United States was less similar to that in MSM from the European countries, with 45% and 46% overlaps for MSM in Sweden and the Netherlands, respectively. Minimum-spanning-tree analysis of MLST/ompA sequence types identified two large clusters that contained almost exclusively samples from MSM and comprised 74% of all MSM samples. Three other clusters were predominated by samples from women but also contained MSM specimens. Of 19 detected variants of the MLST target CT144, three variants were highly associated with MSM. Our study supports the hypotheses of both tissue tropism as well as epidemiological network structures as explanations for the linkage between specific genetic variants and sexual orientation.
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| 7. |
- Christerson, Linus, 1985-, et al.
(författare)
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High-Resolution Genotyping of Chlamydia trachomatis by Use of a Novel Multilocus Typing DNA Microarray
- 2011
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Ingår i: Journal of Clinical Microbiology. - 0095-1137 .- 1098-660X. ; 49:8, s. 2838-2843
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Tidskriftsartikel (refereegranskat)abstract
- Typing of Chlamydia trachomatis is important to understandingits epidemiology. Currently used methods such as DNA sequencingof the ompA gene and multilocus sequence typing (MLST) eitheroffer limited epidemiological resolution or are laborious andexpensive, or both. DNA microarray technology using the ArrayStripformat is an affordable alternative for genotyping. In thisstudy, we developed a new multilocus typing (MLT) DNA microarray,based on the target regions of a high-resolution MLST systemas well as software for easy analysis. Validation of the arraywas done by typing 80 previously MLST-typed clinical specimensfrom unselected adolescents in school. The MLT array showed100% specificity and provided 2.4-times-higher resolution thanompA sequencing, separating the commonly predominating ompAE/Bour genotype into 7 MLT array genotypes. The MLT array reproducedepidemiological findings revealed by the MLST system and showedsufficient sensitivity to work with clinical specimens. Comparedto MLST analysis, the expenses needed for testing a sample withthe MLT array are considerably lower. Moreover, testing canbe completed within 1 working day rather than 3 or 4 days, withdata analysis not requiring highly specialized personnel. Thepresent MLT array represents a powerful alternative in C. trachomatisgenotyping.
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| 8. |
- Gonzales, Lucia, et al.
(författare)
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Molecular Characterization of Enterotoxigenic Escherichia coli Isolates Recovered from Children with Diarrhea during a 4-Year Period (2007 to 2010) in Bolivia
- 2013
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Ingår i: Journal of Clinical Microbiology. - : American Society for Microbiology. - 0095-1137 .- 1098-660X. ; 51:4, s. 1219-1225
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Tidskriftsartikel (refereegranskat)abstract
- Enterotoxigenic Escherichia coli (ETEC) is an important cause of childhood diarrhea. This study aimed to characterize ETEC strains isolated from Bolivian children aged <5 years according to enterotoxin profile, colonization factors (CFs), suggested virulence genes, and severity of disease. A total of 299 ETEC isolates recovered from children with diarrhea and 55 ETEC isolates from children without diarrhea (controls) were isolated over a period of 4 years. Strains expressing heat-labile toxin (LT) or heat-stable toxin (ST) alone were about equally common and twice as common as ETEC producing both toxins (20%). ETEC strains expressing human ST (STh) were more common in children aged <2 years, while ETEC strains expressing LT plus STh (LT/STh) were more frequent in 2- to 5-year-old children. Severity of disease was not related to the toxin profile of the strains. CF-positive isolates were more frequently identified in diarrheal samples than in control samples (P = 0.02). The most common CFs were CFA/I and CS14. CFA/I ETEC strains were more frequent in children aged <2 years than CS1+CS3 isolates and CS14 isolates, which were more prevalent in 2- to 5-year-old children. The presence of suggested ETEC virulence genes (clyA, eatA, tia, tibC, leoA, and east-1) was not associated with disease. However, east-1 was associated with LT/STh strains (P < 0.001), eatA with STh strains (P < 0.001), and tia with LT/STh strains (P < 0.001). A minor seasonal peak of ETEC infections was identified in May during the cold-dry season and coincided with the peak of rotavirus infections; this pattern is unusual for ETEC and may be important for vaccination strategies in Bolivia.
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| 9. |
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| 10. |
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