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Dispatch
Genetic Diversity of Sapovirus
in Children, Australia
Grant S. Hansman,*
Naokazu Takeda,* Kazuhiko Katayama,* Elise T.V. Tu,†‡ Christopher J. McIver,†‡
William D. Rawlinson,†‡ and Peter A. White†
*National Institute of Infectious Diseases, Tokyo, Japan; †University
of New South Wales, Sydney, New South Wales, Australia; and ‡Prince of
Wales Hospital, Sydney, New South Wales, Australia
Suggested
citation for this article
Sapovirus was detected
in 7 of 95 stool specimens from children with gastroenteritis of unknown
etiology in Sydney, Australia, from August 2001 to August 2002 and from
February 2004 to August 2004, by using reverse transcription–polymerase
chain reaction. Sequence analysis of the N-terminal capsid region showed
all human sapovirus genogroups.
Sapovirus (SaV), a member of the genus Sapovirus in the family
Caliciviridae, is an etiologic agent of human gastroenteritis.
SaV-associated infections can cause both mild and acute gastroenteritis.
Symptoms include watery stool, mild and or acute diarrhea, stomach cramps,
nausea, and vomiting (1). In a recent study, the
independent risk factor for SaV gastroenteritis in children was contact
with an index case-patient, usually in daycare centers (2).
The most widely used method of SaV detection is reverse transcription–polymerase
chain reaction (RT-PCR), which has high sensitivity and can be used for
further genetic analysis (3,4). SaV strains can
be divided into 5 genogroups (GI, GII, GIII, GIV, and GV), of which GI,
GII, GIV, and GV strains infect humans, while GIII strains infect pigs
(5,6). The 4 human genogroups can be further divided
into genotypes (7). The purpose of this study
was to describe sapovirus-associated infections in Australia.
The Study
We screened stool specimens for SaV by using RT-PCR and described the
genetic diversity of virus-positive specimens. A total of 95 stool specimens
were collected from children <18 years of age treated for gastrointestinal
illness at the Sydney Children's Hospital. Stool specimens were obtained
from patients with gastroenteritis of unknown origin despite extensive
investigation. These specimens were negative for common foodborne bacterial
pathogens (Salmonella, Shigella, and Campylobacter)
and enteric viruses (rotavirus, adenovirus, astrovirus, and norovirus)
(IDEIA enzyme-linked immunosorbent assay, Dako Cytomation, Ely, UK). The
specimens included 67 of 110 specimens obtained from children hospitalized
between August 2001 and August 2002 and 28 of 60 specimens from outpatients
between February 2004 and August 2004. Specimens were not tested for the
presence of SaV if an etiologic agent was already identified (n = 75).
RNA was extracted and purified as described elsewhere (3).
Ten microliters of RNA was reverse transcribed by using SuperScript III
RNaseH (–) reverse transcriptase according to the manufacture's instructions
(Invitrogen, Carlsbad, CA, USA). PCR was conducted by using a nested approach
with primers directed against the N-terminal capsid region (4).
The PCR products were analyzed by 2% agarose gel electrophoresis and visualized
by staining with ethidium bromide. PCR-generated amplicons were excised
from the gel and purified by using the QIAquick gel extraction kit (Qiagen,
Hilden, Germany). Nucleotide sequences were determined by using the terminator
cycle sequence kit (version 3.1) and the ABI 3100 Avant sequencer (Perkin-Elmer
ABI, Boston, MA, USA). Nucleotide sequences were aligned by using ClustalX,
and distances were calculated by using the 2-parameter method of Kimura
(8). Phylogenetic trees with bootstrap analysis
from 1,000 replicas were generated by using the neighbor-joining method
as described previously (8).
SaV was detected in 7 of 95 stool specimens from children 9 months to
7 years of age with previously unknown causes of acute gastroenteritis.
This represented a minimum prevalence of 4.1% (7 of 170 specimens). Sequence
analysis showed the presence of all known human SaV genogroups (Figure).
Two sequences (strains Sydney31 and Sydney40), which shared ≈99%
nucleotide (nt) identity and belonged to genogroup GI, closely matched
(>99% nt identity) the Manchester sequence. Three sequences (strains
Sydney53, Sydney77, and Sydney4106) that belonged to genogroup GII had
69%–77% nt identity. Sydney4106 had ≈98% nt identity with the Mc10
sequence, Sydney53 had ≈90% nt identity with the C12 sequence, and
Sydney77 had ≈99% nt identity with the Bristol sequence.
We recently reported SaV strains Mc10 and C12 as recombinant strains
(7). Phylogenetic analysis of the nonstructural
region (i.e., genome start to capsid start) grouped Mc10 and C12 in 1
GII cluster (7), and the structural region (i.e.,
capsid start to genome end) grouped Mc10 and C12 into distinct GII genotypes
(7). Evidence suggested that the recombination
site occurred at the polymerase and capsid junction in open reading frame
1, as we recently described with recombinant norovirus strains (9).
Further sequence analysis of the nonstructural region (i.e., 800 nt of
the polymerase gene) showed that Sydney4106 had ≈99% nt identity
with Mc10, and Sydney53 had ≈92% nt identity with C12. These findings
suggest that Sydney4106 and Sydney53 were also recombinant strains and
indicate the widespread distribution and genetic stability of recombinant
SaV strains. One sequence (strain Sydney3) belonged to genogroup GIV and
had ≈99% nt identity with the SW278 sequence, which recently caused
an outbreak of gastroenteritis in adults in Sweden in March 2004 (1).
Another sequence (strain Sydney4402) belonged to genogroup GV and had
100% nt identity with the NK24 sequence, which was isolated from an infant
with gastroenteritis in Thailand in December 2002 (10).
White blood cells were detected in the stool specimens of 3 children infected
with SaV genogroups GII, GIV, and GV (strains Sydney4106, Sydney3, and
Sydney4402, respectively). In our previous study (10),
an infant infected with NK24 (SaV genogroup GV) had a fever for 11 days
and vomiting for 3 days, which was notably longer than the duration of
symptoms in other infants infected with SaV GI and GII strains (unpub.
data). These results suggest that some SaV genogroups could be more virulent
than others, although additional studies are needed.
Conclusions
Little is known about SaV infections in Australia (11–14).
Data from these reports indicate that SaV is an uncommon cause of acute
gastroenteritis in Australia. When the proportion of SaV present in the
total calicivirus isolations was used, SaV was estimated to be the etiologic
agent of gastroenteritis in 0.56% (11), 0.32%
(12), and 0.46% (14)
of cases. Our results have shown that SaV is an important cause of acute
gastroenteritis in children in Sydney, with a minimum prevalence of 4.1%,
which is higher than previously reported. This is the first report of
SaV GIV genogroup-associated infection in Australia and widespread distribution
of SaV. However, a more comprehensive study is needed to determine whether
predominant SaV strains are circulating, as observed with noroviruses
(7,11,15).
This work was supported
by grants-in-aid from the Ministry of Education, Culture, Sports, Science
and Technology, Japan, and a grant for research on reemerging infectious
diseases from the Ministry of Health, Labor, and Welfare, Japan. We
are grateful to the Human Science Foundation of Japan for the Fellowship
provided to Grant Hansman. Elise Tu is supported by a University Postgraduate
Award from the University of New South Wales, Australia.
Dr Hansman is a
researcher at the National Institute of Infectious Diseases, Japan.
His research interests include viruses that cause gastroenteritis in
humans, molecular epidemiology of sapoviruses and noroviruses, expression
of caliciviruses, and serologic cross-reactivity between viral genotypes.
References
- Johansson PJ, Bergentoft K, Larsson PA, Magnusson
G, Widell A, Thorhagen M, et al. A
nosocomial sapovirus-associated outbreak of gastroenteritis in adults.
Scand J Infect Dis. 2005;37:200–4.
- de Wit MA, Koopmans MP, van Duynhoven YT. Risk
factors for norovirus, Sapporo-like virus, and group A rotavirus gastroenteritis.
Emerg Infect Dis. 2003;9:1563–70.
- Hansman GS, Katayama K, Maneekarn N, Peerakome S, Khamrin P, Tonusin
S, et al. Genetic
diversity of norovirus and sapovirus in hospitalized infants with sporadic
cases of acute gastroenteritis in Chiang Mai, Thailand. J Clin Microbiol.
2004;42:1305–7.
- Okada M, Shinozaki K, Ogawa T, Kaiho I. Molecular
epidemiology and phylogenetic analysis of Sapporo-like viruses.
Arch Virol. 2002;147:1445–51.
- Farkas T, Zhong WM, Jing Y, Huang PW, Espinosa SM, Martinez N, et
al. Genetic
diversity among sapoviruses. Arch Virol. 2004;149:1309–23.
- Schuffenecker I, Ando T, Thouvenot D, Lina B, Aymard M. Genetic
classification of “Sapporo-like viruses.” Arch Virol. 2001;146:2115–32.
- Katayama K, Miyoshi T, Uchino K, Oka T, Tanaka T, Takeda N, et al.
Novel
recombinant sapovirus. Emerg Infect Dis. 2004;10:1874–6.
- Katayama K, Shirato-Horikoshi H, Kojima S, Kageyama T, Oka T, Hoshino
F, et al. Phylogenetic
analysis of the complete genome of 18 Norwalk-like viruses. Virology.
2002;299:225–39.
- Bull RA, Hansman GS, Clancy LE, Tanaka MM, Rawlinson WD, White PA.
Norovirus
recombination in ORF1/ORF2 overlap. Emerg Infect Dis. 2005;11:1079–85.
- Guntapong R, Hansman GS, Oka T, Ogawa S, Kageyama T, Pongsuwanna Y,
et al. Norovirus
and sapovirus infections in Thailand. Jpn J Infect Dis. 2004;57:276–8.
- Kirkwood CD, Bishop RF. Molecular
detection of human calicivirus in young children hospitalized with acute
gastroenteritis in Melbourne, Australia, during 1999. J Clin Microbiol.
2001;39:2722–4.
- Wright PJ, Gunesekere IC, Doultree JC, Marshall JA. Small
round-structured (Norwalk-like) viruses and classical human caliciviruses
in southeastern Australia, 1980–1996. J Med Virol. 1998;55:312–20.
- Grohmann G, Glass RI, Gold J, James M, Edwards P, Borg T, et al. Outbreak
of human calicivirus gastroenteritis in a day-care center in Sydney,
Australia. J Clin Microbiol. 1991;29:544–50.
- Kirkwood CD, Clark R, Bogdanovic-Sakran N, Bishop RF. A
5-year study of the prevalence and genetic diversity of human caliciviruses
associated with sporadic cases of acute gastroenteritis in young children
admitted to hospital in Melbourne, Australia (1998–2002). J Med
Virol. 2005;77:96–101.
- White PA, Hansman GS, Li A, Dable J, Isaacs M, Ferson M, et al. Norwalk-like
virus 95/96-US strain is a major cause of gastroenteritis outbreaks
in Australia. J Med Virol. 2002;68:113–8.
Suggested citation
for this article:
Hansman GS, Takeda
N, Katayama K, Tu ETV, McIver CJ, Rawlinson WD, et al. Genetic diversity
of sapovirus in children, Australia. Emerg Infect Dis [serial on the Internet].
2006 Jan [date cited]. Available from http://www.cdc.gov/ncidod/EID/vol12no01/05-0846.htm
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