Molecular typing of adenoviruses in pediatric respiratory infections in Buenos Aires, Argentina (1999–2010)

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Abstract

Background

The human adenovirus (HAdV) types most commonly found in respiratory samples belong to HAdV species C (HAdV-C1, -C2, -C5, and -C6) and to HAdV species B (HAdV-B3 and -B7). Several studies in South America have shown the association between severe respiratory infections and subspecies B1.

Objectives

The aim of this study was to identify the adenovirus types associated with acute lower respiratory tract infections in children, found as single or coinfections, throughout a 12-year period.

Study design

All samples that tested positive for adenovirus by immunofluorescence assay from January 1999 to December 2010 were typed by evaluating a set of four viral genes (E1A, VA, hexon and fiber). Quantitative PCRs for HAdV-B and HAdV-C species were performed to compare the viral load found in single infections and coinfections.

Results

From a total of 743 HAdV, 654 (88%) were single infections and 89 (12%) coinfections. From the 654 single HAdV infections, members of four species were present: species B (n = 492, 75.23%), species C (n = 138, 21.1%), species E (n = 19, 2.91%), and species D (n = 5, 0.76%). Only members of species B (n = 109, 57.67%) and species C (n = 80, 42.33%) were detected in coinfections. HAdV-B7 and HAdV-B3 were the most prevalent types (n = 308, 36.54%; n = 230, 27.28% respectively) and HAdV-C1, -C2, -E4, -C5, -C6, -D8, -B11, -B14 and -B21 were also detected. Viral loads for species C viruses were higher in single infections than in coinfections (p < 0.01), whereas the opposite was observed for species B viruses (p < 0.0001).

Conclusions

This study provides a thorough description of adenovirus circulation and diversity in Buenos Aires in a 12-year period. The high proportion of coinfections found in this work shows that this phenomenom might be more common than expected.

Section snippets

Background

Human adenoviruses (HAdV) belong to the Mastadenovirus genus and are classified into six different species (A–F), with marked differences in tissue tropism and clinical manifestations.1 The types most commonly found in respiratory samples belong to HAdV species C (HAdV-C1, -C2, -C5, and -C6) and to HAdV species B, subspecies B1 (HAdV-B3 and -B7) and B2 (HAdV-B14), which are endemic and epidemic respectively in pediatric populations.2, 3, 4

Rare cases of severe infection, outbreaks in closed

Objectives

The aim of this study was to identify the adenovirus types associated with ALRI in children, found as single or coinfections, by evaluating a set of four viral genes throughout a 12-year period.

Samples

Nasopharyngeal aspirates (NPA) from children hospitalized with clinical diagnosis of ALRI were received at the Virology Laboratory of “Dr. R. Gutiérrez” Children's Hospital (Buenos Aires, Argentina) from January 1999 to December 2010.

Viral studies

Rapid detection of adenovirus was performed by indirect immunofluorescence assay (IFA) with monoclonal antibodies (Light Diagnostics, Chemicon Int., Temecula, CA, USA).19 This research included all samples that tested positive for adenovirus by IFA.

PCR typing

Molecular typing

Viral detection

A total of 48,544 NPA were received at the Virology Laboratory of “Dr. R. Gutiérrez” Children's Hospital and tested for HAdV by IFA from January 1999 to December 2010. Overall, HAdVs were found in 4.7% of the samples, but in 1999, 2002 and 2003, these viruses were significantly more prevalent than in other years (p < 0.000001) (Table 1). Adenovirus circulation showed both an epidemic and an endemic pattern (Supplemmentary Fig. 1).

Molecular typing

PCR sensitivity and specificity were evaluated for each protocol by

Discussion

In this study, 748 samples were analyzed and ten types (HAdV-C1, -C2, -B3, -E4, -C5, -C6, -B7, -D8, -B11 and -B21) of four species (HAdV-B, C, D, E) were found in single infections, whereas only members of species B and C were found in coinfections, including the first HAdV-B14 description in Argentina. This study provides a thorough description of adenovirus circulation and diversity in Buenos Aires in a 12-year period. Although prevalences presented in this work may represent only the cases

Funding

This work was partially supported by ANPCYT, Ministerio de Ciencia, Tecnología e Innovación Productiva de la Nación, Argentina (grant PICT 22147/04 and 1624/07); and by CONICET (grant PIP112-200801-00294).

Competing interests

None declared.

Ethical approval

Not required.

Acknowledgements

We thank P.M. Riveiro, V. Burna, M. Campal, A.M. Caratozzolo, R. Murgo, and M.I. Natale for their excellent technical support.

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