Adenovirus type 11 uses CD46 as a cellular receptor

Abstract

The 51 human adenovirus serotypes are divided into six species (A to F). Many adenoviruses use the coxsackie-adenovirus receptor (CAR) for attachment to host cells in vitro. Species B adenoviruses do not compete with CAR-binding serotypes for binding to host cells, and it has been suggested that species B adenoviruses use a receptor other than CAR. Species B adenoviruses mainly cause disease in the respiratory tract, the eyes, and in the urinary tract. Here we demonstrate that adenovirus type 11 (Ad11; of species B) binds to Chinese hamster ovary (CHO) cells transfected with CD46 (membrane cofactor protein)-cDNA at least 10 times more strongly than to CHO cells transfected with cDNAs encoding CAR or CD55 (decay accelerating factor). Nonpermissive CHO cells were rendered permissive to Ad11 infection upon transfection with CD46-cDNA. Soluble Ad11 fiber knob but not Ad7 or Ad5 knob inhibited binding of Ad11 virions to CD46-transfected cells, and anti-CD46 antibodies inhibited both binding of and infection by Ad11. From these results we conclude that CD46 is a cellular receptor for Ad11.

FIG. 1.

Ad7 and Ad11 virions exhibit increased binding to CHO-CD46 cells. The ability of Ad5 (species C) (A), Ad37 (species D) (B), Ad7 (species B:1) (C), and Ad11 (species B:2) (D) to bind to CHO cells transfected with cDNAs encoding human CAR, CD55 (DAF), and CD46 (BC1 or BC2 isoforms) was investigated as described in Materials and Methods.

FIG. 2.

CD46 expression on A549 cells and CHO cell transfectants. The expression of CD46 on A549 cells, CHO cells, and CHO cells transfected with cDNAs encoding the BC1 and BC2 isoforms of CD46 was investigated by using flow cytometry with the E4.3 monoclonal anti-CD46 antibodies as described in Materials and Methods. Black and white fields represent cells incubated in the absence and presence of anti-CD46 antibodies, respectively.

FIG. 3.

Anti-CD46 antibodies inhibit binding of species B adenoviruses to CHO-BC1 and A549 cells. The binding of Ad7 (A and C) and Ad11 (B and D) virions to CHO-BC1 (A and B) and A549 (C and D) preincubated with or without (CTRL) antibodies was performed as described in Materials and Methods. GB24 and TRA-2-10, monoclonal antibodies directed against the SCRs 3/4 and 1, respectively; Poly, rabbit anti-human CD46 polyclonal antiserum; RmcB and IF7, monoclonal antibodies directed against human CAR and CD55, respectively; rabbit-1 and rabbit-2, serum from two nonimmunized rabbits.

FIG. 4.

CD46 promotes infection of Ad11 in CHO cells. (A) Ad11 virions were allowed to infect CHO cells or CHO cells transfected with cDNAs encoding the BC1 or BC2 isoforms of human CD46, as described in Materials and Methods. (B) CHO-BC1 cells were preincubated with rabbit anti-CD46-serum before infection with Ad11 virions. At 44 h after infection, the cells were fixed, stained, and visualized by using a fluorescent microscope as described in Materials and Methods.

FIG. 5.

Ca²⁺ or Mn²⁺ ions promote binding of Ad7 virions to CHO and CHO-BC1 cells. The ability of ³⁵S-labeled virions to bind to EDTA-pretreated CHO-BC1 (Ad11 [A] and Ad7 [B]) or CHO (Ad7 [C]) cells in the presence of Ca²⁺, Mn²⁺, or Mg²⁺ and either with or without rabbit anti-CD46 serum, was investigated as described in Materials and Methods.

FIG. 6.

Trypsination of CHO-BC1 cells inhibits the binding of Ad7 but enhances the binding of Ad11. The ability of Ad7 and Ad11 virions to bind to CHO-BC1 cells either pretreated with trypsin or left untreated was investigated as described in Materials and Methods.

FIG. 7.

Ad11 fiber knobs block the binding of Ad11 virions to A549 and CHO-BC1 cells. Binding of Ad11 virions to A549 preincubated with homologous fiber knobs or binding to CHO-BC1 cells preincubated with homologous fiber knobs or fiber knobs from Ad5 or Ad7 was investigated as described in Materials and Methods.