II Symptomatic and Asymptomatic Norovirus Infections among Hospitalized Young Children in Xi'an, China Público

Dong, Changxin (2011)

Permanent URL: https://etd.library.emory.edu/concern/etds/zp38wd21g?locale=es
Published

Abstract


Background: Acute gastroenteritis is a major cause of childhood morbidity and mortality
in the world. Noroviruses (NoVs) have been recognized as a common etiology of acute
gastroenteritis in children, but NoVs genotyping and epidemiological information in
China is not well characterized.
Objectives: To determine the NoV prevalence and genotypes associated with pediatric
symptomatic and asymptomatic infections of acute gastroenteritis at the Xi'an Children's
Hospital in Xi'an, China.
Study design: 201 fecal specimens were collected from hospitalized young children with
diarrhea (symptomatic infection), and 53 fecal specimens were collected from gender and
age matched hospitalized children without diarrhea (asymptomatic infection) between
March 2009 and May 2010. NoV TaqMan real-time RT-PCR, conventional RT-PCR, and
sequencing analysis were used to determine the NoV infection rates, circulating NoV
genotypes, and predominant NoV variants.
Results: NoVs were detected in 19.9% (40/201) of children with symptomatic infection
and in 35.8% (19/53) of children with asymptomatic infection. Only NoV GII.3 and GII.4
strains were identified, and the GII.4 sequences were similar to the 2006b variant.
Conclusions: NoVs infection appeared to be high in hospitalized children in China,
indicating that NoV vaccination is urgently needed. In addition, asymptomatic NoV
infection tends to be an important reservoir for NoVs transmission, and a surveillance
network of NoV infections should be established to monitor the trends of NoV molecular
evolution in China.


Table of Contents




TABLE OF CONTENTS

1. INTRODUCTION .................................................................................................................................... 1
2. LITERATURE REVIEW ................................................................................................................... 4
2.1 PATHOGENS THAT CAUSE ACUTE DIARRHEA......................................................................................... 4
2.1.1.1 Campylobacter Bacteria ......................................................................................................................... 4
2.1.1.2 Shigella Bacteria .................................................................................................................................... 4
2.1.1.3 Salmonella Enteritidis Bacteria .............................................................................................................. 6
2.1.1.4 Aeromonas and Plesiomonas .................................................................................................................. 6
2.1.1.5 Vibrio Cholera and Vibrio Parahaemolyticus ........................................................................................ 7
2.1.1.6 Eschericha coli ....................................................................................................................................... 8
2.1.1.7 Clostridium difficile ................................................................................................................................ 9
2.1.2 Parasite ................................................................................................................................................... 10
2.1.2.1 Giardia Parasite ................................................................................................................................... 10
2.1.2.2 Cryptosporidium parasite ..................................................................................................................... 11
2.1.3 Enteric Viruses ............................................................................................................................ 11
2.1.3.1 Rotavirus .............................................................................................................................................. 11
2.1.3.2 Adenovirus ........................................................................................................................................... 13
2.1.3.3 Astrovirus ............................................................................................................................................. 13
2.1.3.4 Human calicivirus ................................................................................................................................. 14
2.2 LABORATORY DIAGNOSIS FOR NOROVIRUS ......................................................................................... 17
2.2.1 Electron microscope (EM) ............................................................................................................ 18
2.2.2 Reverse Transcription PCR (RT-PCR) ............................................................................................ 18
2.2.3 Quantitative real-time RT-PCR ..................................................................................................... 19
2.2.4 Enzyme immunoassay (EIA) ......................................................................................................... 19
3. MATERIAL AND METHODS......................................................................................................... 19
3.1 STUDY POPULATION AND STUDY DESIGN ............................................................................................ 20
3.2 CLINICAL SAMPLES COLLECTION AND LABORATORY METHODS ......................................................... 21
3.2.1 Stool sample collection ................................................................................................................ 21
3.2.2 Norovirus RNA extraction ............................................................................................................ 21
3.2.3 Norovirus detection by TaqMan Real-time RT-PCR ................................................................... 22
3.2.4 Positive Norovirus amplification by conventional RT-PCR ...................................................... 23
3.2.5 Strategy for determining the full-length GII.4 capsid sequence .................................................. 24
3.2.6 Electrophoresis and sequencing................................................................................................... 25
3.2.7 Phylogenetic analysis ................................................................................................................... 26
3.2.8 Statistical and phylogenetic analytical methods ......................................................................... 26
3.3 RESULTS .............................................................................................................................................. 27
3.3.1 Epidemiological characteristics of study population ................................................................... 27
3.3.2 Norovirus detection using RT-qPCR ............................................................................................. 27

VIII

3.3.3 Amplification and sequencing of the GII positive samples using the conventional RT-PCR ......... 28
3.3.4 Amplification of the fragment 2 and fragment 3 in the GII.4 capsid region ................................ 31
3.3.5 Subclustering of GII.4 variants using partial and full-length capsid sequences ........................... 32
4. DISCUSSION, CONCLUSION AND RECOMMENDATION ....................................................... 35
4.1 DISCUSSION ......................................................................................................................................... 35
4.2 CONCLUSION........................................................................................................................................ 38
4.3 RECOMMENDATION ............................................................................................................................. 39
REFERENCE ....................................................................................................................................... 40

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