Skip directly to site content Skip directly to page options Skip directly to A-Z link Skip directly to A-Z link Skip directly to A-Z link
Volume 17, Number 12—December 2011
Letter

Novel Astroviruses in Children, Egypt

On This Page
Figures
Article Metrics
25
citations of this article
EID Journal Metrics on Scopus

Cite This Article

To the Editor: Human astroviruses (HAstVs) are a common cause of gastroenteritis in children, the elderly, and immunocompromised persons (1). Up to 10% of acute viral gastroenteritis in children and 0.5%–15% of diarrheal outbreaks are attributed to astroviruses (2). Until 2008, eight classical astrovirus serotypes were known to cause human disease; in Egypt, HAstV-1 is the most frequent astrovirus serotype detected (3). Recently, 5 novel astroviruses have been discovered in human fecal samples from patients with diarrhea or acute flaccid paralysis (47). Because the prevalence of these virsues in the Middle East is unknown, we screened fecal samples from children with diarrhea residing in Egypt to ascertain the prevalence and diversity of these novel astroviruses.

Fecal samples were collected from a cohort of 364 symptomatic children <5 years of age who had diarrhea and were seeking medical care at Abu Homos Hospital in the Nile Delta of Egypt from September 2006 through September 2007. RNA was extracted from 10% fecal suspensions and reverse transcription PCR for astrovirus was performed as previously described (46). Astrovirus consensus primer pair SF0073/SF0076 amplified an ≈409-bp region of open reading frame (ORF) 1b, encoding the RNA polymerase gene. PCR-positive samples were then tested by using primer sets Mon269–Mon270 (8) and SF0053–SF0061, amplifying either a 449-bp or a 402-bp product of the ORF2 capsid gene from classical HAstVs (serotypes I–VIII) or astrovirus MLB1, respectively. DNA sequences of PCR products were determined by using Big Dye Terminator Cycle technology (Applied Biosystems, Foster City, CA, USA). Nucleotide sequences were compared with sequences obtained from GenBank. Phylogenies were constructed with the MEGA4 software (www.megasoftware.net) by using the neighbor-joining method and a p-distance algorithm. Bootstrap resampling was performed by using 2,000 replicates to demonstrate robustness of grouping. The nucleotide sequences determined in this study were assigned GenBank accession nos. HQ674630–HQ674650.

Figure

Thumbnail of A) Phylogenetic analysis of the partial amino acid sequences of the open reading frame (ORF) 2 capsid region of human astrovirus (HAstV) types I–VIII (using Mon primer) with other sequences from GenBank. B, C) Phylogenetic trees based on partial nucleotide sequences of MLB1 ORF2 (B) and ORF1b (VA2) (C). Egyptian isolates are shown in boldface. Sequence alignment was performed by using ClustalW in the BioEdit software package (www.clustal.org). Dendrograms were constructed by using t

Figure. A) Phylogenetic analysis of the partial amino acid sequences of the open reading frame (ORF) 2 capsid region of human astrovirus (HAstV) types I–VIII (using Mon primer) with other sequences from...

Consensus astrovirus reverse transcription PCR results were positive in 23 (6.3%) of 364 fecal samples. Five common serotypes of classical HAstV were identified constituting 16 (70%) of 23 positive samples; HAstV type I was most prevalent (n = 9). Alignment of the partial amino acid sequences of the ORF2 capsid region indicates that Egyptian HAstV type I strains share 99%–100% identity (Figure, panel A).

Five of the 7 remaining positive samples were most closely related to MLB1 on the basis of the partial ORF2 sequence analysis. Egypt MLB1 samples shared ≈99%-nt identity with each other, and all grouped in 1 phylogenetic cluster (Figure, panel B) along with a recently identified MLB1 strain (GenBank accession no. HM450380 [9]) isolated from a human fecal sample in Hong Kong. The Egypt MLB1 strains shared ≈97%-nt identity with the prototype MLB1 Australia strain but were more divergent from an isolate recently described in the United States (92% nt identity, GenBank accession no. FJ222451). However, all of the observed nucleotide differences represented silent mutations between Egypt MLB1 and Australia and US isolates; comparison of partial capsid protein sequences indicated no amino acid changes.

The 2 remaining HAstV-positive samples were phylogenetically most similar to astrovirus VA2 (VA2) (Figure, panel B). On the basis of the sequence of the amplicon from the ORF1b region, the Egyptian VA2 isolates shared 96.1%–100% aa identity to previously described VA2 and astrovirus human/mink/ovine genomes in GenBank.

Our study describes the detection of the recently identified viruses MLB1 and VA2 in a cohort of symptomatic children with diarrhea residing in Egypt. This study expands the geographic range of these viruses to include northern Africa. The consensus primers used in our study were able to detect a higher percentage of positive HAstV serotypes I–VIII than the Mon340/Astman-2 primers (10) (data not shown), a finding that encourages use of these primers to screen humans with gastroenteritis for astroviruses. Increased understanding of the genetic diversity within viral families infecting humans will assist in future studies of their pathogenicity and the design of specific diagnostic assays. Further epidemiologic studies, including clinical cases and demographically matched healthy controls, are required to better define their pathogenic potential.

Top

Acknowledgment

This work was supported by the Global Emerging Infections and Surveillance System, a Division of the Armed Forces Health Surveillance Center and in part by the National Institutes of Health under KL2 RR024994. The study protocol DOD NAMRU3.2000.0002 (IRB Protocol No. 096) was hospital-based surveillance for enteric pathogens associated with severe diarrhea in Egyptian children.

Top

Salwa F. AhmedComments to Author , Peter J. Sebeny, John D. Klena, Guillermo Pimentel, Adel Mansour, Amel M. Naguib, Jody Bruton, Sylvia Y.N. Young, Lori R. Holtz, and David Wang
Author affiliations: US Naval Medical Research Unit No.3, Cairo, Egypt (S.F. Ahmed, P.J. Sebeny, J.D. Klena, G. Pimentel, A. Mansour, J. Bruton, S.Y.N. Young); Ministry of Health, Cairo (A.M. Naguib); Washington University School of Medicine, St. Louis, Missouri, USA (L.R. Holtz, D. Wang)

Top

References

  1. Klein  EJ, Boster  DR, Stapp  JR, Wells  JG, Qin  X, Clausen  CR, Diarrhea etiology in a children’s hospital emergency department: a prospective cohort study. Clin Infect Dis. 2006;43:80713. DOIPubMedGoogle Scholar
  2. Lyman  WH, Walsh  JF, Kotch  JB, Weber  DJ, Gunn  E, Vinje  J. Prospective study of etiologic agents of acute gastroenteritis outbreaks in child care centers. J Pediatr. 2009;154:2537. DOIPubMedGoogle Scholar
  3. Naficy  AB, Rao  MR, Holmes  JL, Abu-Elyazeed  R, Savarino  SJ, Wierzba  TF, Astrovirus diarrhea in Egyptian children. J Infect Dis. 2000;182:68590. DOIPubMedGoogle Scholar
  4. Finkbeiner  SR, Kirkwood  CD, Wang  D. Complete genome sequence of a highly divergent astrovirus isolated from a child with acute diarrhea. Virol J. 2008;5:117.PubMedGoogle Scholar
  5. Finkbeiner  SR, Holtz  LR, Jiang  Y, Rajendran  P, Franz  CJ, Zhao  G, Human stool contains a previously unrecognized diversity of novel astroviruses. Virol J. 2009;6:161. DOIPubMedGoogle Scholar
  6. Finkbeiner  SR, Li  Y, Ruone  S, Conrardy  C, Gregoricus  N, Toney  D, Identification of a novel astrovirus (astrovirus VA1) associated with an outbreak of acute gastroenteritis. J Virol. 2009;83:108369. DOIPubMedGoogle Scholar
  7. Kapoor  A, Li  L, Victoria  J, Odernide  B, Mason  C, Pandey  P, Multiple novel astrovirus species in human stool. J Gen Virol. 2009;90:296572. DOIPubMedGoogle Scholar
  8. Noel  JS, Lee  TW, Kurtz  JB, Glass  RI, Monroe  SS. Typing of human astroviruses from clinical isolates by enzyme immunoassay and nucleotide sequencimg. J Clin Microbiol. 1995;33:797801.PubMedGoogle Scholar
  9. Chu  DK, Chin  AW, Smith  GJ, Chan  KH, Guan  Y, Peiris  JS, Detection of novel astroviruses in urban brown rats and previously known astroviruses in humans. J Gen Virol. 2010;10:245762. DOIPubMedGoogle Scholar
  10. Rohayem  J, Berger  S, Juretzek  T, Herchenroder  O, Mogel  M, Poppe  M, A simple and rapid single-step m-RT-PCR to detect norovirus, astrovirus and adenovirus in clinical stool samples. J Virol Methods. 2004;118:4959. DOIPubMedGoogle Scholar

Top

Figure

Top

Cite This Article

DOI: 10.3201/eid1712.110909

Related Links

Top

Table of Contents – Volume 17, Number 12—December 2011

EID Search Options
presentation_01 Advanced Article Search – Search articles by author and/or keyword.
presentation_01 Articles by Country Search – Search articles by the topic country.
presentation_01 Article Type Search – Search articles by article type and issue.

Top

Comments

Please use the form below to submit correspondence to the authors or contact them at the following address:

Salwa F. Ahmed, US Naval Medical Research Unit No. 3 (NAMRU-3), PSC 452 Box 5000, FPO AE 09835, USA

Send To

10000 character(s) remaining.

Top

Page created: November 18, 2011
Page updated: November 18, 2011
Page reviewed: November 18, 2011
The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.
file_external