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

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.

Abbreviations: HAdV, Human adenoviruses, IFA, Immunofluorescent Assay, qPCRs, Quantitative PCRs, ALRI, Acute lower respiratory tract infections, NPA, Nasopharyngeal aspirates

Keywords: Human adenoviruses, Coinfections, Viral load