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- Bucardo, Filemon, et al.
(författare)
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Pediatric norovirus diarrhea in Nicaragua
- 2008
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Ingår i: Journal of Clinical Microbiology. - 0095-1137 .- 1098-660X. ; 46:8, s. 2573-2580
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Tidskriftsartikel (refereegranskat)abstract
- Information about norovirus (NoV) infections in Central America is limited. Through a passive community and hospital pediatric diarrhea surveillance program, a total of 542 stool samples were collected between March 2005 and February 2006 in León, Nicaragua. NoV was detected in 12% (65/542) of the children; of these, 11% (45/409) were in the community and 15% (20/133) were in the hospital, with most strains (88%) belonging to genogroup II. NoV infections were age and gender associated, with children of <2 years of age (P < 0.05) and girls (P < 0.05) being most affected. Breast-feeding did not reduce the number of NoV infections. An important proportion (57%) of NoV-infected children were coinfected with diarrheagenic Escherichia coli. A significant proportion (18/31) of NoV-positive children with dehydration required intravenous rehydration. Nucleotide sequence analysis (38/65) of the N-terminal and shell region in the capsid gene revealed that at least six genotypes (GI.4, GII.2, GII.4, GII.7, GII.17, and a potentially novel cluster termed "GII.18-Nica") circulated during the study period, with GII.4 virus being predominant (26/38). The majority (20/26) of those GII.4 strains shared high nucleotide homology (99%) with the globally emerging Hunter strain. The mean viral load was approximately 15-fold higher in children infected with GII.4 virus than in those infected with other G.II viruses, with the highest viral load observed for the group of children infected with GII.4 and requiring intravenous rehydration. This study, the first of its type from a Central American country, suggests that NoV is an important etiological agent of acute diarrhea among children of <2 years of age in Nicaragua.
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| 4. |
- Nordgren, Johan, et al.
(författare)
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Novel Light-Upon-Extension Real-Time PCR Assay for Simultaneous Detection, Quantification, and Genogrouping of Group A Rotavirus
- 2010
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Ingår i: JOURNAL OF CLINICAL MICROBIOLOGY. - : American Society for Microbiology. - 0095-1137. ; 48:5, s. 1859-1865
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Tidskriftsartikel (refereegranskat)abstract
- We have developed a light-upon-extension (LUX) real-time PCR assay for detection, quantification, and genogrouping of group A rotavirus (RV), the most common cause of acute gastroenteritis in children. The LUX system uses a fluorophore attached to one primer and having a self-quenching hairpin structure, making it cost-effective and specific. We designed genogroup-specific primers having different fluorophores, making it possible to differentiate between the two main genogroups of human group A RVs. The assay was applied on clinical stool specimens from Sweden and Central America (n = 196) and compared to immunological and conventional PCR assays. The genogrouping ability was further validated against a subset of clinical specimens, which had been genogrouped using monoclonal antibodies. Our real-time PCR assay detected and quantified all positive specimens (n = 145) and exhibited higher sensitivity than immunological assays and conventional PCR. The assay exhibited a wide dynamic range, detecting from 5 to andgt; 10(7) genes per PCR, resulting in a theoretical lower detection limit of andlt; 10,000 viruses per gram of stool. No cross-reaction was observed with specimens containing norovirus, sapovirus, astrovirus, or adenovirus. In total, 22 (15%) of the positive clinical specimens were identified as genogroup I, 122 (84%) were identified as genogroup II, and 1 specimen was found to contain a mix of both genogroups. All genogroup I-positive specimens were associated with capsid glycoprotein 2 (G2). No significant difference in viral load was found between genogroups or geographic region. The detection and quantification, combined with the genogrouping ability, make this assay a valuable tool both for diagnostics and for molecular epidemiological investigations.
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| 5. |
- Nordgren, Johan, 1980-, et al.
(författare)
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Novel light-upon-extension real-time PCR assays for detection and quantification of genogroup I and II noroviruses in clinical specimens
- 2008
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Ingår i: Journal of Clinical Microbiology. - 0095-1137 .- 1098-660X. ; 46:1, s. 164-170
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Tidskriftsartikel (refereegranskat)abstract
- Norovirus is now recognized as the leading cause of nonbacterial acute gastroenteritis in adults, causing numerous outbreaks worldwide. We have developed two novel light-upon-extension (LUX) real-time PCR assays for detection and quantification of norovirus genogroups I and II. The LUX system uses a fluorophore attached to one primer having a self-quenching hairpin structure, making it cost-effective and specific. The assays were evaluated against clinical stool specimens (n = 103) from Sweden and Nicaragua and compared to established methods. The norovirus assay detected more positive stool specimens (47/103) than conventional PCR (39/103) and corresponded to a TaqMan real-time PCR, with the exception of one specimen. Furthermore, the assays correctly identified all (n = 11) coded control specimens in a reference panel containing various genogroups and genotypes. Both LUX real-time PCR assays had a wide dynamic range, detecting from < or = 10(1) to 10(7) genes per reaction, resulting in a theoretical lower limit of < or = approximately 20,000 viruses per gram of stool. No cross-reactivity was noticed with specimens containing other enteric viruses, and by using melting curve analysis we could differentiate between norovirus genogroups I and II.
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| 7. |
- Wilhelmsson, Peter, et al.
(författare)
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Prevalence and Diversity of Borrelia Species in Ticks That Have Bitten Humans in Sweden
- 2010
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Ingår i: JOURNAL OF CLINICAL MICROBIOLOGY. - : American Society for Microbiology. - 0095-1137 .- 1098-660X. ; 48:11, s. 4169-4176
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Tidskriftsartikel (refereegranskat)abstract
- Members of the genus Borrelia are among the most common infectious agents causing tick-borne disease in humans worldwide. Here, we developed a Light Upon eXtension (LUX) real-time PCR assay that can detect and quantify Borrelia species in ticks that have fed on humans, and we applied the assay to 399 such ticks. Borrelia PCR-positive ticks were identified to species level by sequencing the products of conventional PCR performed using Borrelia group-specific primers. There was a 19% prevalence of Borrelia spp. in the detached ticks, and the number of spirochetes per Borrelia PCR-positive tick ranged from 2.0 x 10(2) to 4.9 x 10(5), with a median of 7.8 x 10(3) spirochetes. Adult ticks had a significantly larger number of spirochetes, with a median of 8.4 x 10(4) compared to the median of nymphs of 4.4 x 10(4). Adult ticks also exhibited a higher prevalence of Borrelia (33%) than nymphs (14%). Among the identified species, Borrelia afzelii was found to predominate (61%) and was followed by B. garinii (23%), B. valaisiana (13%), B. burgdorferi sensu stricto (1%), B. lusitaniae (1%), and B. miyamotoi-like (1%). Also, 3% of the ticks were coinfected with multiple strains of B. afzelii. Notably, this is the first report of B. lusitaniae being detected in ticks in Sweden. Our LUX real-time PCR assay proved to be more sensitive than a corresponding TaqMan assay. In conclusion, the novel LUX real-time PCR method is a rapid and sensitive tool for detection and quantification of Borrelia spp. in ticks.
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