published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

Gastroenteritis in the form of diarrhea and vomiting is common in human and is mostly caused by viral infection. As the significant proportion of gastrointestinal infections are still not diagnosed, novel viruses are suggested to be the causative agents of unknown gastroenteritis. Novel and emerging picornaviruses, including human parechovirus (HPeV), Aichi virus (AiV) and salivirus (SalV) are suggested to play an important role in acute gastroenteritis. Since little was known about the molecular and clinical epidemiology of these viruses, the present study aims to investigate the presence of HPeV, AiV and SalV in fecal samples of children with acute gastroenteritis in Hong Kong. Retrospective and prospective studies were performed using fecal samples from pediatric patients hospitalized for acute gastroenteritis from November 2004 to August 2005, August 2006 to October 2006 and September 2012 to August 2013. Among 1708 fecal samples subjected to RT-PCR using primers targeted to 5’NCR of picornaviruses, viruses were detected in 57 samples, with 47 patients (2.8%) positive for HPeVs, three patients (0.18%) positive for AiV and one patient (0.1%) positive for SalV. Phylogenetic analysis of the partial VP1 capsid gene of the 33 HPeV strains revealed the presence of genotypes of HPeV- 1, 3, 4, 5, 7, 10, among which HPeV1 was the predominant genotype circulating in our population. The peak activity of HPeV infection was in autumn. Of the three children with AiV detected in fecal samples, phylogenetic analysis of the partial VP1 and 3CD regions indicated the three AiV strains from fecal samples belonged to the AiV genotype A. Co-detection of different pathogens was noted in 6 samples (10.5%) of 57 stool samples positive for picornaviruses. Among the five samples with HPeV, co-detection with HBoV, AiV, SalV and Aeromonas were observed. In one sample with AiV, picobirnavirus was identified. In conclusion, HPeV, AiV and SalV were found to be present in fecal samples of Hong Kong children with gastroenteritis, with HPeV being the most common virus detected. Routine screening for these viruses in young children with gastroenteritis may better define their epidemiology and help prevent their transmission. / published_or_final_version / Microbiology / Master / Master of Medical Sciences

Salmonella infections remain one of the most common food borne diseases worldwide. Gastroenteritis, which can be caused by many non-typhoidal Salmonella (NTS) serovars, is relatively common in North America. One of the main risk factors of NTS gastroenteritis is travel to endemic areas in the developing world. The current treatment of NTS infections with antibiotics is reserved for severe cases. A growing concern with antibiotic use is that clinical isolates are becoming drug resistant. Although most NTS infections are self-limiting in nature, the burden on the body and recovery can take several months. Thus, it is vital to prevent NTS infections rather than solely rely on treatment. We have previously discovered two novel surface associated polysaccharides in Salmonella: O-Antigen capsule and X-factor. Not only O-Antigen Capsule is considered a common surface antigen, but its’ genes were found to be expressed during in vivo infections in mice. Such an antigen would be a suitable candidate in developing a vaccine against Salmonella induced gastroenteritis. The goal of this research was to evaluate the use of O-Antigen capsule to develop a traveler’s vaccine for NTS associated gastroenteritis. Results and Conclusions: We have developed a purification protocol and purified the capsule and X-factor from Salmonella Typhimurium, Enteritidis, and Heidelberg. Lipopolysaccharide (LPS) was co-isolated with O-Antigen capsule, but removed using Triton extraction. Salmonella LPS is strain-specific and an adaptive immune response against LPS will not provide cross-protection. We generated specific immune sera in rabbits to recognize O-Antigen capsule and X-factor produced by Salmonella Typhimurium and Enteritidis. We used a mouse model to determine the immunization dose of O-Antigen capsule and showed that conjugation is necessary to enhance the immune response in mice. To boost capsule production, we analyzed PyihUTSRQPO activity using a luciferase-based reporter system. Deletion of a putative transcriptional repressor (YihW) resulted in over 100-fold increase in PyihUTSRQPO confirming YihW as a repressor. We have also looked at the effect of growth media, temperature, and sugar precursors on PyihUTSRQPO activity, and were able to show that PyihUTSRQPO has highest activity in Tryptone broth at 30oC in the absence of any additional sugars.

Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 5 uppsatser.

Thesis (MSc (Veterinary Tropical Diseases, Veterinary Science))--University of Pretoria, 2008. / Includes bibliographical references. Also available in print format.

京都大学 / 新制・論文博士 / 博士(社会健康医学) / 乙第13455号 / 論社医博第17号 / 新制||社医||11(附属図書館) / 京都大学大学院医学研究科社会健康医学系専攻 / (主査)教授 長尾 美紀, 教授 近藤 尚己, 教授 中川 一路 / 学位規則第4条第2項該当 / Doctor of Public Health / Kyoto University / DFAM

Norovirus Gastroenteritis Leading to Partial Small Bowel Obstruction David Berry DO, Arthur Cecchini DO, Koushik Sanku MD, Bhavesh Gajjar MD Berrydw@etsu.edu, Cecchini@etsu.edu, Sankuk@etsu.edu, Gajjarb@etsu.edu Department of Internal Medicine, Quillen College of Medicine, East Tennessee State University BACKGROUND Acute gastroenteritis (AGE) is a common problem in both inpatient and outpatient settings. Most cases are viral in origin, with norovirus being the most cited. Typical symptoms include low-grade fever, chills, nausea, vomiting, and abdominal discomfort. The physical examination is usually unremarkable, but abdominal tenderness or signs of volume depletion may be present in severe disease. Most patients have spontaneous remission within a few days and do not require hospitalization or diagnostic evaluation. Laboratory evaluation is often helpful in severe disease, immunocompromised patients, or when bloody or mucoid diarrhea is present. Polymerase chain reaction (PCR) gastrointestinal multiplex testing is often the preferred evaluation as it has a high sensitivity, specificity, and turnaround time when compared to traditional stool studies of enzyme-immunoassay studies. Treatment is often supportive, but specific bacterial and parasitic pathogens should prompt treatment with antimicrobial therapy. CASE PRESENTATION This case presents a 47-year-old male with no known previous medical history or history of intraabdominal surgeries. He presented with four days of progressive nausea, vomiting, diarrhea, and abdominal discomfort. The physical examination revealed a distended and tender abdomen. The metabolic panel did not show any electrolyte derangements. Computed tomography with intravenous contrast revealed partial small bowel obstruction versus less likely ileus. Gastrointestinal pathogen PCR returned positive for norovirus. The patient was given intravenous fluid, nausea control, and pain control, his diet was advanced, and his symptoms subsequently resolved. We believe this case to be unusual, as most cases of viral gastroenteritis are uncomplicated, and this patient presented with radiographic evidence of ileus versus partial small bowel obstruction. PCR testing revealed positivity for norovirus. He had no previous abdominal surgeries or family history of early intestinal malignancies, and the symptoms spontaneously resolved with several days of conservative management, making another etiology much less likely. CONCLUSION AGE is a common diagnosis seen in the primary care clinic, and most patients have an uneventful recovery. However, suspicion of partial obstruction or intestinal ileus should arise when severe abdominal pain and prolonged vomiting are present.

No description available.

High levels of fecal indicator bacteria (e.g. E. coli) are the leading cause of identified surface water impairments in the United States. The US Clean Water Act of 1972 requires that jurisdictions establish priority rankings for impaired waterways and develop a Total Maximum Daily Load (TMDL) plan for each. Although past research indicates that the risk of illness to humans varies by source of fecal contamination, current watershed assessments are developed according to total concentration of indicator bacteria, with all sources weighed equally. A stochastic model using Quantitative Microbial Risk assessment (QMRA) principles to translate source-specific (e.g. human, livestock) daily average concentrations of E.coli into a daily average risk of gastroenteritis infection was developed and applied to Pigg River, an impaired watershed in southern Virginia. Exposure was calculated by multiplying a ratio of source related reference pathogens to predicted concentrations of E.coli and a series of qualifying scalars. Risk of infection was then determined using appropriate dose response relationships. Overall, human and goose sources resulted in the greatest human health risk, despite larger overall E.coli loading associated with cattle. Bacterial load reductions specified in the Pigg River TMDL were applied using Hydrological Simulation Program- FORTRAN (HSPF) to assess the effect these reductions would have on the risk of infection attributed to each modeled bacterial source. Although individual risk sources (neglecting geese) were reduced below the EPA limit of 8 illnesses per 1000 exposures, the combined risk of illness varied between 0.006 and 64 illnesses per 1000 exposures. / Master of Science

Humane Astroviren (HAstV) stellen wichtige Erreger kindlicher Gastroenteritiden dar, die in ihrer Bedeutung lange Zeit unterschätzt wurden. Sie werden in acht Serotypen klassifiziert, die nach dem bisherigen Kenntnisstand mit den Genotypen korrespondieren. Ziel dieser Arbeit war es, Einsicht in die molekulare Epidemiologie der in Deutschland zirkulierenden Astroviren zu vermitteln. Eine HAstV-spezifische RT-PCR bildete die Grundlage für die phylogenetische Analyse eines Genomabschnitts, der für die Kapsidproteine des Virus kodiert. Dazu wurden 16 deutsche Astrovirusisolate aus den Jahren 1997-1999 unter Einbeziehung bereits publizierter Sequenzdaten der Serotypen 1-8 untersucht. In Anlehnung an ein in der vorliegenden Literatur verwendetes Klassifizierungsschema erfolgte die Einteilung der deutschen Isolate in unterschiedliche Genotypen. Hierbei bildete eine Konvergenz von mindestens 85% das Kriterium für die Zuordnung differenter Isolate zum gleichen Genotyp. Es konnte gezeigt werden, dass in Deutschland wenigstens vier HAstV-Genotypen (1-4) kozirkulieren. Über dem betrachteten Genomabschnitt stimmten einige Isolate aus unterschiedlichen geografischen Regionen in ihrer Sequenz überein. Im Rahmen dieser Arbeit wurde erstmals die Totalsequenz eines humanen Astrovirus vom Serotyp 3 ermittelt. Während in der phylogenetischen Analyse des betreffenden Isolats nur ein Genomabschnitt betrachtet wurde, ließ sich an seiner Totalsequenz demonstrieren, dass die Einordnung in den Geno- bzw. Serotyp 3 auch in anderen Genomregionen Gültigkeit besitzt. Analog zu den bisher bekannten Gesamtgenomsequenzen der Serotypen 1, 2 und 8 lassen sich drei überlappende offene Leseraster (ORFs) identifizieren. In den beiden am 5'-Ende gelegenen ORFs 1a und 1b erweisen sich die putativen Motive der Protease und der RNA-Polymerase zwischen den vier Serotypen als hochkonserviert, ebenso wie vier potentielle Transmembrandomänen, ein ribosomales frameshift-Signal und ein nukleäres Lokalisationssignal. In dem am 3'-Ende gelegenen ORF 2 befinden sich drei hochkonservierte potentielle N-Glykosylierungs-Sites sowie ein hochkonserviertes Glykosaminoglykan-Attachment-Site. Ein wesentlicher Befund im Zusammenhang mit der Totalsequenz ist der Nachweis einer 45 Nukleotide umfassenden Deletion im ORF1a im Originalmaterial (Stuhl). Diese wurde bisher nur bei Astroviren gefunden, die in Zellen kultiviert wurden. Von Interesse und weiteren Untersuchungen vorbehalten ist ihre Nähe zur nukleären Lokalisationssequenz, die für die Beeinflussung des Zielzell-Tropismus von Astroviren verantwortlich sein könnte. / Human astroviruses (HastV) are an important cause of infantile gastroenteritis. To date, there are eight recognized serotypes which correlate with genotypes. The aim of this study was to investigate the molecular epidemiology of astroviruses circulating in Germany. Based on a HAstV-specific RT-PCR, phylogenetic analysis of a segment of the capsid protein gene was performed. The examination included sequence data of 16 German astrovirus isolates from the years 1997-1999 as well as published sequence information of the serotypes 1-8. Molecular typing was carried out following published classification strategies. The criterion for classification of isolates into one genotype was sequence identity of at least 85%. Astroviruses of at least four different genotypes (1-4) were found to cocirculate in Germany. The nucleotide sequences of several isolates from different geographical regions were identical. As part of this study, the complete genomic sequence of a type 3 human astrovirus was determined. The classification of the virus as a genotype 3 astrovirus as suggested by phylogenetic analysis over a limited genome section was supported by sequence comparison over two different genomic regions. Similar to the known total sequences of serotypes 1,2 and 8, three overlapping open reading frames (ORFs) were identified. The 5' end ORFs 1a and 1b contain the putative protease and polymerase motifs, which are highly conserved between the four serotypes. A high degree of sequence identity was also found for four potential transmembrane domains, a ribosomal frameshift signal and a nuclear localisation signal. The 3' end ORF 2 encodes three almost totally conserved potential N-glycosylation sites and one highly conserved putative glycosaminoglycan attachment site. As an outstanding feature, the virus, which was isolated and sequenced directly from diarrheal feces, presents a 45-nucleotide deletion in ORF 1 a. This deletion has previously only been found in cell cultured astroviruses. Further studies are needed to determine whether all viral genomes within the quasispecies carry the deletion.