Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99


Search Results: 1 - 8 of 8 matches for " Siriphan Boonsilp "
All listed articles are free for downloading (OA Articles)
Page 1 /8
Display every page Item
Molecular detection and speciation of pathogenic Leptospira spp. in blood from patients with culture-negative leptospirosis
Siriphan Boonsilp, Janjira Thaipadungpanit, Premjit Amornchai, Vanaporn Wuthiekanun, Wirongrong Chierakul, Direk Limmathurotsakul, Nicholas P Day, Sharon J Peacock
BMC Infectious Diseases , 2011, DOI: 10.1186/1471-2334-11-338
Abstract: We evaluated our hypothesis during a prospective study of 418 consecutive patients presenting to a hospital in northeast Thailand with an acute febrile illness. Admission blood samples were taken for Leptospira culture and PCR. A single tube nested PCR that amplified a region of the rrs gene was developed and applied, amplicons sequenced and a phylogenetic tree reconstructed.39/418 (9%) patients were culture-positive for Leptospira spp., and 81/418 (19%) patients were culture-negative but rrs PCR-positive. The species associated with culture-positive leptospirosis (37 L. interrogans and 2 L. borgpetersenii) were comparable to those associated with culture-negative, PCR-positive leptospirosis (76 L. interrogans, 4 L. borgpetersenii, 1 unidentified, possibly new species).Molecular speciation failed to identify a unique bacterial subset in patients with culture-negative, PCR-positive leptospirosis. The rate of false-negative culture was high, and we speculate that antibiotic pre-treatment is the most likely explanation for this.Leptospirosis is an acute febrile illness caused by pathogenic species belonging to the genus Leptospira [1,2]. This zoonotic disease has a worldwide distribution but is most common in tropical and subtropical regions and has the greatest impact on public health in developing countries [1-4]. Disease is maintained by chronic carrier hosts that excrete the organism into the environment, and infection in man results from direct contact with infected animals or indirect contact with a contaminated environment [1-3].Leptospira are present in the blood during the first week of infective symptoms [1,2]. Culture is rarely performed in routine clinical practice since this may take several months and requires considerable expertise, which places it within the domain of specialist reference centres. Culture continues to have an important role, however, in defining the global epidemiology of infection [4]. Identification of the serovar of infecting isolate
Comparison of Two Multilocus Sequence Based Genotyping Schemes for Leptospira Species
Ahmed Ahmed equal contributor ,Janjira Thaipadungpanit equal contributor,Siriphan Boonsilp,Vanaporn Wuthiekanun,Kishore Nalam,Brian G. Spratt,David M. Aanensen,Lee D. Smythe,Niyaz Ahmed,Edward J. Feil,Rudy A. Hartskeerl,Sharon J. Peacock
PLOS Neglected Tropical Diseases , 2011, DOI: 10.1371/journal.pntd.0001374
Abstract: Background Several sequence based genotyping schemes have been developed for Leptospira spp. The objective of this study was to genotype a collection of clinical and reference isolates using the two most commonly used schemes and compare and contrast the results. Methods and Findings A total of 48 isolates consisting of L. interrogans (n = 40) and L. kirschneri (n = 8) were typed by the 7 locus MLST scheme described by Thaipadungpanit et al., and the 6 locus genotyping scheme described by Ahmed et al., (termed 7L and 6L, respectively). Two L. interrogans isolates were not typed using 6L because of a deletion of three nucleotides in lipL32. The remaining 46 isolates were resolved into 21 sequence types (STs) by 7L, and 30 genotypes by 6L. Overall nucleotide diversity (based on concatenated sequence) was 3.6% and 2.3% for 7L and 6L, respectively. The D value (discriminatory ability) of 7L and 6L were comparable, i.e. 92.0 (95% CI 87.5–96.5) vs. 93.5 (95% CI 88.6–98.4). The dN/dS ratios calculated for each locus indicated that none were under positive selection. Neighbor joining trees were reconstructed based on the concatenated sequences for each scheme. Both trees showed two distinct groups corresponding to L. interrogans and L. kirschneri, and both identified two clones containing 10 and 7 clinical isolates, respectively. There were six instances in which 6L split single STs as defined by 7L into closely related clusters. We noted two discrepancies between the trees in which the genetic relatedness between two pairs of strains were more closely related by 7L than by 6L. Conclusions This genetic analysis indicates that the two schemes are comparable. We discuss their practical advantages and disadvantages.
A Single Multilocus Sequence Typing (MLST) Scheme for Seven Pathogenic Leptospira Species
Siriphan Boonsilp equal contributor,Janjira Thaipadungpanit equal contributor ,Premjit Amornchai,Vanaporn Wuthiekanun,Mark S. Bailey,Matthew T. G. Holden,Cuicai Zhang,Xiugao Jiang,Nobuo Koizumi,Kyle Taylor,Renee Galloway,Alex R. Hoffmaster,Scott Craig,Lee D. Smythe,Rudy A. Hartskeerl,Nicholas P. Day,Narisara Chantratita,Edward J. Feil,David M. Aanensen,Brian G. Spratt,Sharon J. Peacock
PLOS Neglected Tropical Diseases , 2013, DOI: 10.1371/journal.pntd.0001954
Abstract: Background The available Leptospira multilocus sequence typing (MLST) scheme supported by a MLST website is limited to L. interrogans and L. kirschneri. Our aim was to broaden the utility of this scheme to incorporate a total of seven pathogenic species. Methodology and Findings We modified the existing scheme by replacing one of the seven MLST loci (fadD was changed to caiB), as the former gene did not appear to be present in some pathogenic species. Comparison of the original and modified schemes using data for L. interrogans and L. kirschneri demonstrated that the discriminatory power of the two schemes was not significantly different. The modified scheme was used to further characterize 325 isolates (L. alexanderi [n = 5], L. borgpetersenii [n = 34], L. interrogans [n = 222], L. kirschneri [n = 29], L. noguchii [n = 9], L. santarosai [n = 10], and L. weilii [n = 16]). Phylogenetic analysis using concatenated sequences of the 7 loci demonstrated that each species corresponded to a discrete clade, and that no strains were misclassified at the species level. Comparison between genotype and serovar was possible for 254 isolates. Of the 31 sequence types (STs) represented by at least two isolates, 18 STs included isolates assigned to two or three different serovars. Conversely, 14 serovars were identified that contained between 2 to 10 different STs. New observations were made on the global phylogeography of Leptospira spp., and the utility of MLST in making associations between human disease and specific maintenance hosts was demonstrated. Conclusion The new MLST scheme, supported by an updated MLST website, allows the characterization and species assignment of isolates of the seven major pathogenic species associated with leptospirosis.
Morphological and Ultrastructural Observations on the Blood Cells of Sand Lizards (Leiolepis belliana Rubritaeniata) Mertens 1961
Siriphan Ponsen,Nual-Anong Narkkong,Warapol Angwanich
Journal of Animal and Veterinary Advances , 2012,
Abstract: The objective of this study was to examine the erythrocytes, leukocytes and thrombocytes of the sand lizard (Leiolepsis belliana rubritaeniata Mertens 1961) by light and electron (SEM and TEM) microscopy. Smears were prepared from blood from the heart of ten healthy adult sand lizards (five males and five females). Electron microscopy was also performed on all samples. The results revealed the following information: light microscopy finding; erythrocyte, lymphocyte, monocyte, heterophil, basophil, eosinophil and thrombocyte presented district morphology. Erythrocytes, mononuclear cells, granulocytes and thrombocytes of the sand lizard were nearly similar to those of chickens, snakes, tortoises, turtles and other lizards. SEM finding, the lymphocyte showed tiny round cells. The monocyte was larger than the lymphocyte and had a round cell shape and rough membrane. The heterophil was a round or elongated cell with a rough membrane. The basophil was tiny and round with a rough membrane surface. The Eosinophil was a round cell with many spherical spines protruded from their membrane surface. The thrombocyte was a tiny cell with an irregular membrane. TEM finding, the nucleus of the lymphocyte was large and round with heterochromatin. The nucleus of the monocyte was mononuclear, kidney shaped with heterochromatin. The nucleus of the heterophil was lobuled with heterochromatin, dense cytoplasm and contained spindle, drum-bell or long shape granules. The nucleus of the basophil was lobuled with heterochromatin and the cytoplasm contained large amount of strip granules. The nucleus of the eosinophil was round and had a dense cytoplasm and contained large bowling pin and round-shape liked granules. The nucleus of thrombocyte was dense with clear cytoplasm and no organelle appearance.
Fitness Costs of Mutations at the HIV-1 Capsid Hexamerization Interface
Siriphan Manocheewa, J. Victor Swain, Erinn Lanxon-Cookson, Morgane Rolland, James I. Mullins
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0066065
Abstract: The recently available x-ray crystal structure of HIV-1 capsid hexamers has provided insight into the molecular interactions crucial for the virus’s mature capsid formation. Amino acid changes at these interaction points are likely to have a strong impact on capsid functionality and, hence, viral infectivity and replication fitness. To test this hypothesis, we introduced the most frequently observed single amino acid substitution at 30 sites: 12 at the capsid hexamerization interface and 18 at non-interface sites. Mutations at the interface sites were more likely to be lethal (Fisher’s exact test p = 0.027) and had greater negative impact on viral replication fitness (Wilcoxon rank sum test p = 0.040). Among the interface mutations studied, those located in the cluster of hydrophobic contacts at NTD-NTD interface and those that disrupted NTD-CTD inter-domain helix capping hydrogen bonds were the most detrimental, indicating that these interactions are particularly important for maintaining capsid structure and/or function. These functionally constrained sites provide potential targets for novel HIV drug development and vaccine immunogen design.
Diagnostic Accuracy of Real-Time PCR Assays Targeting 16S rRNA and lipl32 Genes for Human Leptospirosis in Thailand: A Case-Control Study
Janjira Thaipadunpanit,Wirongrong Chierakul,Vanaporn Wuthiekanun,Direk Limmathurotsakul,Premjit Amornchai,Siriphan Boonslip,Lee D. Smythe,Roongrueng Limpaiboon,Alex R. Hoffmaster,Nicholas P. J. Day,Sharon J. Peacock
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0016236
Abstract: Rapid PCR-based tests for the diagnosis of leptospirosis can provide information that contributes towards early patient management, but these have not been adopted in Thailand. Here, we compare the diagnostic sensitivity and specificity of two real-time PCR assays targeting rrs or lipL32 for the diagnosis of leptospirosis in northeast Thailand.
Impact of Mutations in Highly Conserved Amino Acids of the HIV-1 Gag-p24 and Env-gp120 Proteins on Viral Replication in Different Genetic Backgrounds
Yi Liu, Ushnal Rao, Jan McClure, Philip Konopa, Siriphan Manocheewa, Moon Kim, Lennie Chen, Ryan M. Troyer, Denis M. Tebit, Sarah Holte, Eric J. Arts, James I. Mullins
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0094240
Abstract: It has been hypothesized that a single mutation at a highly conserved amino acid site (HCS) can be severely deleterious to HIV in most if not all isolate-specific genetic backgrounds. Consequently, potentially universal HIV-1 vaccines exclusively targeting highly conserved regions of the viral proteome have been proposed. To test this hypothesis, we examined the impact of 10 Gag-p24 and 9 Env-gp120 HCS single mutations on viral fitness. In the original founder sequence of the subject in whom these mutations were identified, all Gag-p24 HCS mutations significantly reduced viral replication fitness, including 7 that were lethal. Similar results were obtained at 9/10 sites when the same mutations were introduced into the founder sequences of two epidemiologically unlinked subjects. In contrast, none of the 9 Env-gp120 HCS mutations were lethal in the original founder sequence, and four had no fitness cost. Hence, HCS mutations in Gag-p24 are likely to be severely deleterious in different HIV-1 subtype B backgrounds; however, some HCS mutations in both Gag-p24 and Env-gp120 fragments can be well tolerated. Therefore, when designing HIV-1 immunogens that are intended to force the virus to nonviable escape pathways, the fitness constraints on the HIV segments included should be considered beyond their conservation level.
Amino-Acid Co-Variation in HIV-1 Gag Subtype C: HLA-Mediated Selection Pressure and Compensatory Dynamics
Morgane Rolland,Jonathan M. Carlson,Siriphan Manocheewa,J. Victor Swain,Erinn Lanxon-Cookson,Wenjie Deng,Christine M. Rousseau,Dana N. Raugi,Gerald H. Learn,Brandon S. Maust,Hoosen Coovadia,Thumbi Ndung'u,Philip J. R. Goulder,Bruce D. Walker,Christian Brander,David E. Heckerman,James I. Mullins
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0012463
Abstract: Despite high potential for HIV-1 genetic variation, the emergence of some mutations is constrained by fitness costs, and may be associated with compensatory amino acid (AA) co-variation. To characterize the interplay between Cytotoxic T Lymphocyte (CTL)-mediated pressure and HIV-1 evolutionary pathways, we investigated AA co-variation in Gag sequences obtained from 449 South African individuals chronically infected with HIV-1 subtype C.
Page 1 /8
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.