published_or_final_version / Microbiology / 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

Background: Respiratory tract infection is one of the major diseases to cause morbidity and mortality worldwide. Undiagnosed respiratory infection remains unclear. Picornavirus is most common to cause respiratory infection after the influenza virus and RSV. There were numerous notorious pathogens in the Picornaviridae family, for instance, human parechovirus and Saffold virus. These emerging and novel viruses are reported sporadically in respiratory infection and amongst children in particular. This study is aimed to assess the potential role of HPeV and SAFV in respiratory infection in Hong Kong. Methods: Between May 2013 and April 2014, nasopharyngeal aspirates (NPA) were collected from hospitalized patients who have respiratory infection. The collected samples were tested negative for respiratory syncytial virus, adenovirus, influenza A and B viruses, parainfluenza viruses types 1, 2 and 3 by direct immunofluorescence. RT-PCR was used to target the HPeV and SAFV corresponding region of 5'UTR and analyze by the BioEdit sequence Alignment Editor and Basic Local Alignment Search Tool. Results: 597 female and 603 male were included in 1200 NPA samples. 20% of these samples were under the age of 5. However, there were no HPeV and SAFV detected in all 1200 NPA samples. Conclusion: To reveal the possible association between viruses and respiratory infection, the sampling size and district area should be expanded. The single detection method may not be able to detect all the viruses in the current study. / published_or_final_version / Microbiology / Master / Master of Medical Sciences