PCR Analysis of Egyptian Respiratory Adenovirus Isolates, Including Identification of Species, Serotypes, and Coinfections

Abstract

Eighty-eight adenovirus (Ad) isolates and associated clinical data were collected from walk-in patients with influenza-like illness in Egypt during routine influenza surveillance from 1999 through 2002. Respiratory Ad distributions are geographically variable, and serotype prevalence has not been previously characterized in this region. Serotype identity is clinically relevant because it predicts vaccine efficacy and correlates strongly with both clinical presentation and epidemiological pattern. Species and serotype identities were determined using several well-validated multiplex PCR protocols culled from the literature and supplemented with a few novel primer sets designed to identify rare types. The isolates included common species B1 serotypes (Ad3 and Ad7), common species C serotypes (Ad1, Ad2, and Ad5), the less common species B2 serotype Ad11, and three isolates of the rare species B1 serotype Ad16. Two isolates that appear to be variant Ad16 were also identified. Fifteen coinfections of multiple adenoviral types, primarily AdB/AdC and Ad3/Ad7 dual infections, were detected. The majority of these were verified using redundant PCR tests targeted at multiple genes. PCR is able to resolve coinfections, in contrast to traditional serum neutralization tests. PCR is also comparatively rapid and requires very little equipment. Application of the method allowed an inclusive determination of the serotypes found in the Egyptian respiratory sample set and demonstrated that coinfections are common and may play a previously unrecognized role in adenovirus pathogenesis, evolution, and epidemiology. In particular, coinfections may influence adenoviral evolution, as interserotypic recombination has been identified as a source of emerging strains.

Quantitative Real-Time PCR Assay Panel for Detection and Type-Specific Identification of Epidemic Respiratory Human Adenoviruses

“…To complement this assay, in this study we developed additional type-specific qPCR assays that run under conditions identical to those for other HAdVs documented to cause ARI outbreaks, including HAdV types 3, 4, 7, 11, and 21. We also developed an assay for the rarely identified species B HAdV-16, found to be associated with cases of acute febrile respiratory illness in Egypt (33) and Kenya (unpublished data) that may pose a future risk of spread outside these regions.…”

Adenovirus Microsatellite Reveals Dynamics of Transmission during a Recent Epidemic of Human Adenovirus Serotype 14 Infection

“…Most adults are immune to these serotypes. The sole HAdV-E serotype, HAdV-4, and several HAdV-B serotypes, including HAdV-3, HAdV-7, and HAdV-21, are commonly associated with epidemic outbreaks of FRI and pneumonia in healthy adults and children throughout the world (16,17,24,21). Two other HAdV-B serotypes, HAdV-11a and HAdV-14, had, until recently, been identified only in association with respiratory disease epidemics in rare (though severe) outbreaks in Eurasia (3,5,16).…”

“…The second polymorphism was an insertion/deletion mutation in a mononucleotide microsatellite repeat, consisting of 17 consecutive thymidines [T (17)] in one sequenced isolate and T (13) in the other. This polymorphism was identified in the noncoding region at the 3Ј end of the terminal binding protein (TBP) gene.…”

Molecular Characterization of an Adenovirus 3-16 Intertypic Recombinant Isolated in Argentina from an Infant Hospitalized with Acute Respiratory Infection

“…Based on the few reports published in the literature, HAdV-16 and intertypic recombinants involving HAdV-16 appear to be rarely associated with cases of acute respiratory disease requiring hospitalization (3,12). In addition, their infrequent detection during surveillance studies of HAdV-associated respiratory disease suggests that these viruses may have a restricted geographic area of circulation and/or not be particularly virulent.…”