A New Group B Adenovirus Receptor Is Expressed at High Levels on Human Stem and Tumor Cells

Abstract

CD46 is used by human group B adenoviruses (Ads) as a high-affinity attachment receptor. Here we show evidence that several group B Ads utilize an additional receptor for infection of human cells, which is different from CD46. We tentatively named this receptor receptor X. Competition studies with unlabeled and labeled Ads, recombinant Ad fiber knobs, and soluble CD46 and CD46 antibodies revealed three different subgroups of group B Ads, in terms of their receptor usage. Group I (Ad16, -21, -35, and -50) nearly exclusively uses CD46. Group II (Ad3, -7p, and -14) utilizes receptor X and not CD46. Group III (Ad11p) uses both CD46 and the alternative receptor X. Interaction of group II and III Ads with receptor X occurs via the fiber knob. Receptor X is an abundantly expressed glycoprotein that interacts with group II and III Ads at relatively low affinity in a Ca 2؉ -dependent manner. This receptor is expressed at high levels on human mesenchymal and undifferentiated embryonic stem cells, as well as on human cancer cell lines. These findings have practical implications for stem cell and gene therapy.Human adenoviruses (Ads) have been classified into six subgroups (A to F) currently containing 51 serotypes. Group B Ads form two genetic clusters, B1 (Ad3, Ad7, Ad16, Ad21, and Ad50) and B2 (Ad11, Ad14, Ad34, and Ad35) (44). Most B1 Ads are mainly associated with acute respiratory disease and, unlike the species C Ads (e.g., Ad5), do not establish persistence (43). The B2 serotypes 11p, 34, and 35 have mainly been associated with infections of the kidneys and urinary tract. Recently, gene transfer vectors based on group B Ads have shown promise for cell and gene therapy. Vectors containing fibers from group B Ads efficiently transduce human cell types that are relatively refractory to infection with classical serotype Ad5 vectors, including malignant tumor cells (30, 39), hematopoietic stem cells (26,35,46), mesenchymal stem (MES) cells (9, 18), dendritic cells (DC) (5, 27, 28), lymphocytes (33), chorion villus cells, and endothelial cells (13).CD46 has been identified as a cellular receptor for group B Ads (7, 32, 37) whereby the two distal extracellular domains of CD46 are involved in Ad binding (6, 7). In humans, CD46 is a ubiquitously expressed membrane protein with complement regulatory functions.A series of data suggest the existence of an additional group B Ad receptor(s). (i) Several groups found that Ad3 and Ad7 do not use CD46 for infection (7, 21), (ii) Ad3 and Ad7 (group B1) and Ad35 (group B2) do not compete for binding on HeLa cells (31,35), and (iii) Ad11p fiber knob can completely block binding of wild-type Ad35 to A549 cells, while recombinant Ad35 fiber knob cannot completely block Ad11p binding (22,41). While these data suggest that Ad3 and Ad7 and probably Ad11 can use a receptor that is different from CD46, the nature of this receptor(s) remains elusive. In this study, we investigated receptor usage by group B Ads on human cells and laid the groundwork for identification of the receptor. Also, the...

Wild-type adenoviruses from groups A–F evoke unique innate immune responses, of which HAd3 and SAd23 are partially complement dependent

“…As suggested by a recent study, these results may indicate utilization of the unknown group B receptor 'X', used specifically by HAd3, HAd7 and HAd14 in this tropic phenomenon. 17 We also found high levels of the group D representative HAd37 in the spleen as well as the liver, levels similar to those quantified for HAd5. Like group B Ads, HAd37 also uses CD46 as a receptor, but i.v.…”

“…Ad serotypes from all human subgenera use CAR as a receptor with the exception of group B Ads and some group D Ads (for example, HAd37) that use a variety of receptors including CD46, sialic acid and the unknown receptor 'X'. [15][16][17] Multiple Ad serotypes are currently under investigation for their potential ability to uniquely target various tissues and/or evade HAd5-specific innate and adaptive immune responses. 18,19 To date, various members of groups A-F have been vectorized and evaluated in vitro and/or in vivo.…”

In vivo transduction of primitive mobilized hematopoietic stem cells after intravenous injection of integrating adenovirus vectors

“…Both others and we have shown that Ad vectors containing the Ad35 fiber or fiber knob (Ad5/35) efficiently transduce human and non-human primate HSPCs in vitro. [7][8][9][10] Integration site analysis Genomic DNA was isolated from GFP 1 hCD46tg colonies using the DNeasy Blood and Tissue Kit (Qiagen, Valencia, CA). These CFU colonies were obtained from Lin 2 /GFP 1 BM cells of in vivo transduced hCD46tg animals.…”

Interaction of penton base Arg-Gly-Asp motifs with integrins is crucial for adenovirus serotype 35 vector transduction in human hematopoietic cells

“…The present study indicates that the interaction of penton base RGD motifs in Ad35 with integrins is not largely involved with the cellular binding and uptake of Ad35. Segerman et al 32 and Tuve et al 33 also demonstrated that the presence of divalent cations, which increases the affinity of integrins to their ligands, did not affect the cellular binding of subgroup B Ads. Properties of CD46 also contribute to the lack of necessity of interaction between penton base RGD motifs and integrins for uptake of Ad35.…”