engleski

Human adenovirus type 26 uses αv integrin for infection of human epithelial cells

Human adenovirus vectors based on type 5 (HAdV5) are the most commonly investigated adenoviral vectors for gene therapy and vaccination. Limitations for using AdV5 as a vector are activation of the host innate immune responses as well as preexisting immunity to AdV5 wild type, therefore development of new strategies to evade undesired anti vector host immune responses is needed. Currently the most studied approach is the search for other types of adenoviruses that occur at low prevalence in human populations. One of the rare human adenovirus types that is under evaluation includes human adenovirus type 26 (HAdV26). HAdV26 belongs to subgroup D and its natural tropism is still unknown. HAdV26 has RGD motif in penton base and relatively short fiber with only 7 to 8 shaft repeats. Unlike HAdV5, HAdV26 does not bind coagulation factor X. While HAdV26 immunogenicity in vivo is rather well described, basic biology of this virus, like receptor usage, is studied less extensive and less well defined. Hence, the main objective of this study was to investigate transduction efficacy and cell entry of HAdV26 in epithelial cells. As a cell model we used A549 and SK-OV-3 cells which have different expression of known adenovirus receptors: CAR, CD46 and αv integrin. We showed that HAdV26 transduces SK- OV-3 cells 4 times better than A549 indicating that SK-OV-3 cells might express molecule/s that HAdV26 uses as a receptor. Thus, we downregulated CAR, CD46 and αv integrin in A549 and SK-OV-3 cells and subsequently measured transduction efficacy and binding of HAdV26. Downregulation of αv integrin significantly decreased transduction efficacy and binding of HAdV26 in both A549 and SK-OV-3 cells. We obtained the same effect by measuring transduction efficacy of HAdV26 after antibody- mediated blocking of αv integrin Namely, blocking αv integrin in A549 cells efficiently decreased transduction efficacy of HAdV26. These results were further confirmed in A549 cells with increased expression of αv integrin. We stably transfected A549 cells with αv integrin expression plasmid and showed that overexpression of αv integrin increases binding and transduction efficacy of HAdV26 in A549 cells. Based on our results we conclude that HAdV26 uses αv integrin for infection of epithelial cells. Further experiments needed to understand the fundamental molecular characteristics of HAdV26 are ongoing.

adenovirus ; receptor ; endocitoza ; integrin

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