Human Adenoviruses of Subgenera B, C, and E with Various Tropisms Differ in Both Binding to and Replication in the Epithelial A549 and 293 Cells

Abstract

Adenoviruses of six subgenera, namely, adenovirus 31 (Ad31) (subgenus A), Ad3, Ad7, Ad11p, Ad11a, and Ad35 (subgenus B), Ad5v and Ad5p (subgenus C), Ad37 (subgenus D), Ad4 (subgenus E), and Ad41 (subgenus F), were studied. The relative binding properties of different adenoviruses to 293 (human kidney embryonic cells) and A549 (human lung carcinoma cells) cells were compared by flow cytometry. All analyzed adenoviruses bound to cells in a dose-dependent manner. The binding capacity showed that Ad11p, Ad35 (subgenus B:2) with kidney tropism, and Ad4 (subgenus E), which can cause adenopharyngoconjunctivitis, bound strongly to both A549 and 293 cells. The other members of subgenus B and Ad37 of subgenus D manifested an intermediate binding capacity. The analyzed adenoviruses of subgenera A, C, and F manifested a low affinity. Adenoviruses of subgenera B:2 and E manifested high binding affinity to preparations of cell membranes from the epithelial cell lines. Reciprocal competition experiments using Ad11p and Ad4 demonstrated that the two viruses did not block each other. Antibodies against alphavbeta3 and alphavbeta5 reduced the binding of Ad5v virions and slightly impaired the binding of Ad4 but did not affect Ad11p binding to the A549 cell surface. Recombinant fiber proteins of Ad11p and Ad35 reciprocally blocked the binding of both viruses to the epithelial cells but they could not block Ad4. The hexon protein expression of Ad11p and Ad4 was 100 times more efficient than that of the Ad5 vector (pFG140), whereas the infectivity of Ad11p and Ad4 was 40- to 200-fold that of the commonly used Ad5v vector. Taken together, our findings demonstrate that Ad11p and Ad4 bind different receptor molecules and that the fibers of these two viruses provide the predominant high degree of binding, which obviously is a requirement for subsequent internalization and efficacious expression.

Adenovirus Type 11 Uses CD46 as a Cellular Receptor

“…The main disadvantages with Ad5-based vectors appear to be low transduction of target cells and high preexisting immunity (2,13,20,24,34,48,68,74). In several cases, species B:2 adenoviruses have been shown to attach to host cells and deliver genes much more efficiently than other adenoviruses, including Ad5 (43,44,50,57,62). Thus, we believe that the identification of CD46 as a cellular receptor for these adenoviruses widens the understanding of adenovirus tropism and may also contribute to development of more effective adenovirus-based gene therapy vectors.…”

Subgroup B and F Fiber Chimeras Eliminate Normal Adenovirus Type 5 Vector Transduction In Vitro and In Vivo

“…However, we have clearly demonstrated that the F7 vector has a dramatic effect on Ad5 vector detargeting, which substantiates its use as a platform for retargeting (in place of a mutated CAR binding fiber). Subgroup B viruses have been shown to have distinct cell targets, as previously described (20,(23)(24)(25)33), and it will be important to identify the receptor used by the subgroup B viruses as well as the functional ligand domain present in the F7 homotrimer. The extension of the non-CAR binding vectors to the F7F41S tandem platform represents a novel class of modified Ad5-based vectors that provides distinct advantages over traditional single-fiber swap chimeras.…”

“…A CAR binding serotype can be converted to a subgroup B receptor-targeted vector simply by genetically switching the fiber terminal exons (12). Subgroup B viruses can bind to many of the same cell types as CAR binding viruses, but there are also cell types that demonstrate differential affinity for the subgroup B fiber versus the CAR binding serotypes (20,(23)(24)(25)33). Another distinct class of fiber-containing adenoviruses is the enteric subgroup F viruses (serotypes 40 and 41).…”

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

“…(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.…”