II Symptomatic and Asymptomatic Norovirus Infections among Hospitalized Young Children in Xi'an, China Pubblico
Dong, Changxin (2011)
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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