Patricia Pring-Akerblom

Publications of Patricia Pring-Akerblom

• Phylogenetic analysis and structural predictions of human adenovirus penton proteins as a basis for tissue-specific adenovirus vector design.

  Authors: Ijad Madisch, Soeren Hofmayer, Christian Moritz, Alexander Grintzalis, Jens Hainmueller, Patricia Pring-Akerblom, Albert Heim

  Journal of virology. 09/2007; 81(15):8270-81.

  The penton base is a major capsid protein of human adenoviruses (HAdV) which forms the vertices of the capsid and interacts with hexon and fiber protein. Two hypervariable loops of the penton areThe penton base is a major capsid protein of human adenoviruses (HAdV) which forms the vertices of the capsid and interacts with hexon and fiber protein. Two hypervariable loops of the penton are exposed on the capsid surface. Sequences of these and 300 adjacent amino acid residues of all 51 HAdV and closely related simian adenoviruses were studied. Adjacent sequences and predicted overall secondary structure were conserved. Phylogenetic analysis revealed clustering corresponding to the HAdV species and recombination events in the origin of HAdV prototypes. All HAdV except serotypes 40 and 41 of species F exhibited an integrin binding RGD motif in the second loop. The lengths of the loops (HVR1 and RGD loops) varied significantly between HAdV species with the longest RGD loop observed in species C and the longest HVR1 in species B. Long loops may permit the insertion of motifs that modify tissue tropism. Genetic analysis of HAdV prime strain p17'H30, a neutralization variant of HAdV-D17, indicated the significance of nonhexon neutralization epitopes for HAdV immune escape. Fourteen highly conserved motifs of the penton base were analyzed by site-directed mutagenesis of HAdV-D8 and tested for sustained induction of early cytopathic effects. Thus, three new motifs essential for penton base function were identified additionally to the RGD site, which interacts with a secondary cellular receptor responsible for internalization. Therefore, our penton primary structure data and secondary structure modeling in combination with the recently published fiber knob sequences may permit the rational design of tissue-specific adenoviral vectors.

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• Rapid and quantitative detection of human adenovirus DNA by real-time PCR.

  Authors: Albert Heim, Carmen Ebnet, Gabi Harste, Patricia Pring-Akerblom

  Journal of medical virology. 06/2003; 70(2):228-39.

  Rapid diagnosis of human adenovirus (HAdV) infections was achieved by PCR in the recent years. However, conventional PCR has the risk of carry-over contamination due to open handling with itsRapid diagnosis of human adenovirus (HAdV) infections was achieved by PCR in the recent years. However, conventional PCR has the risk of carry-over contamination due to open handling with its products, and results are only qualitative. Therefore, a quantitative "real-time" PCR with consensus primer and probe (dual fluorescence labelled, "TaqMan") sequences for a conserved region of the hexon gene was designed and evaluated. Real-time PCR detected all 51 HAdV prototypes. Sensitivity of the assay was <or=15 copies/run and the linear range of quantitation 1.5 x 10(1) to 1.5 x 10(8) copies/run. TaqMan PCR gave identical results compared to an established conventional one-step PCR protocol in 218 (38 positive and 180 negative) of 234 clinical samples including blood, serum, eye swabs, and feces, and had divergent results in 16 samples (15 positive only in TaqMan PCR, all with low copy numbers, and one positive only in conventional PCR), indicating a higher sensitivity of TaqMan PCR. Adenovirus viremia was detected by TaqMan PCR in 4 of 27 (14.8%) paediatric and 8 of 93 (8.6%) adult stem cell transplant recipients but only in 5 of 306 healthy controls (blood donors, 1.6%). Virus loads of pediatric patients (median 1.7 x 10(5)) were significantly higher than in adult patients (median 2.3 x 10(3)) and than in controls (all samples <or=1.7 x 10(3) copies/ml). A few immunosuppressed children had very high virus loads (up to 1.1 x 10(10) copies/ml), which were associated with symptoms of disseminated disease. In conclusion, real-time PCR is a sensitive and quantitative procedure for the detection of adenovirus infections.

• Adenovirus type 37 binds to cell surface sialic acid through a charge-dependent interaction.

  Authors: Niklas Arnberg, Alistair H. Kidd, Karin Edlund, Jonas Nilsson, Patricia Pring-Akerblom, Göran Wadell

  Virology. 11/2002; 302(1):33-43.

  Most adenoviruses use the coxsackie-adenovirus receptor (CAR) as a major cellular receptor. We have shown recently that adenovirus types 8, 19a, and 37, which are the major causes of epidemicMost adenoviruses use the coxsackie-adenovirus receptor (CAR) as a major cellular receptor. We have shown recently that adenovirus types 8, 19a, and 37, which are the major causes of epidemic keratoconjunctivitis, use sialic acid rather than CAR as a major cellular receptor. The predicted isoelectric point of the receptor-interacting knob domain in the adenovirus fiber protein is unusually high (9.0-9.1) in type 8, 19a, and 37. The pKa of sialic acid is low, 2.6, implying a possible involvement of charge in fiber knob-sialic acid interactions. Here we show that (i) positively charged adenovirus knobs require sialic acid for efficient cell membrane interactions; (ii) viral and knob interactions with immobilized sialic acid or cell-surface sialic acid are sensitive to increased ionic strength; (iii) negatively charged molecules such as sulfated glycosaminoglycans inhibit the binding of virions to target cells in a nonspecific, charge-dependent manner; and that (iv) the ability of adenovirus knobs to interact with sialic acid correlates with the overall charge on the top surface of the respective knobs as predicted by homology modeling. Taken together, the results presented provide strong evidence for a charge mechanism during the interaction between the Ad37 fiber knob and sialic acid.

• Adenovirus type 37 uses sialic acid as a cellular receptor on Chang C cells.

  Authors: Niklas Arnberg, Patricia Pring-Akerblom, Göran Wadell

  Journal of virology. 10/2002; 76(17):8834-41.

  Epidemic keratoconjunctivitis (EKC) is a severe eye infection caused mainly by adenovirus type 8 (Ad8), Ad19, and Ad37. We have shown that the EKC-causing adenoviruses use sialic acid as a cellularEpidemic keratoconjunctivitis (EKC) is a severe eye infection caused mainly by adenovirus type 8 (Ad8), Ad19, and Ad37. We have shown that the EKC-causing adenoviruses use sialic acid as a cellular receptor on A549 cells instead of the coxsackie-adenovirus receptor, which is used by most adenoviruses. Recently, Wu et al. (Virology 279:78-89, 2001) proposed that Ad37 uses a 50-kDa protein as a receptor on Chang C conjunctival cells and that this interaction is independent of sialic acid. According to the American Type Culture Collection, this cell line carries HeLa cell markers and should be considered to be a genital cell line. This prompted us to investigate the function of sialic acid as a cellular receptor for Ad37 in Chang C cells. In this study, we demonstrate that enzymatic removal or lectin-mediated blocking of cell surface sialic acid inhibits the binding of Ad37 virions to Chang C cells, as does soluble, virion-interacting sialic acid-containing substances. The binding was Ca2+ or Mg2+ ion independent and mediated by the knob domain of the trimeric viral fiber polypeptide. Moreover, Ad37 virions infected Chang C cells and two other genital cell lines (HeLa and SiHa) as well as a corneal cell line in a strictly sialic acid-dependent manner. From these results, we conclude that Ad37 uses sialic acid as a major receptor in cell lines derived from both genital and corneal tissues.