Human adenoviruses in respiratory infections: Sequencing of the hexon hypervariable region reveals high sequence variability

BackgroundIn respiratory infections, human adenoviruses (hAdV) of species B1 and C are frequently detected, but severe or even fatal disease outbreaks are predominantly caused by only few serotypes. The molecular typing of hAdV hexon sequences can help to speed up the discrimination of serotypes, thus improving on-time epidemiological examinations and patient care.ObjectivesWe aimed to develop a molecular method for the rapid species B1 and C serotype identification in respiratory samples based on sequence generation of the hexon hypervariable region (HVR).Study designWe developed two PCR-based genotyping systems for a generic HVR amplification and sequence determination of species B1 and C viruses. The assays were applied to hAdV prototypes and 106 samples.ResultsThe primer sets proved to be capable of amplifying all B1 and C serotypes. The viruses detected in clinical samples belong to serotypes 1, 2, 3, 5 and 6. The obtained sequences of serotypes 2, 3 and 5 form 2–3 phylogenetic clusters that are based on the characteristic amino acid changes within the variable HVR sites.ConclusionsOur assay can significantly speed up the time-span needed for serotype identification and will improve epidemiological surveillance and patient care. The obtained hexon sequences of field viruses vary significantly and form multiple genetic lineages. The variability is focussed on the HVR sites and can be interpreted as the ongoing evolutionary process. Further research is needed on the hexon sequence variability of other (respiratory) hAdV serotypes.