title: Complement component C1q and anti-hexon antibody mediate adenovirus infection of a CAR-negative cell line.
abstract: Realization of the potential clinical utility of recombinant adenovirus for gene therapy or vaccine development depends on a better understanding of the role of naturally occurring or therapy-induced anti-adenovirus antibodies. This study addresses the impact of anti-adenovirus neutralizing antibodies and the complement protein C1q on adenovirus infection of coxsackie and adenovirus receptor (CAR)-positive, and especially CAR-negative cells. Initially, transduction efficiency of adenovirus vectors was assessed in the presence or absence of human sera derived from healthy individuals that were seropositive for anti-adenovirus neutralizing antibodies. Infection was monitored by transgene expression in vitro using a replication-deficient adenovirus encoding green fluorescent protein (Ad-GFP). HeLa cells (CAR-positive) were readily infected by Ad-GFP and increasing concentrations of pooled sera increasingly inhibited infection. In contrast, rhabdomyosarcoma (RD) cells, a CAR-negative cell, were poorly infected by Ad-GFP. However, in the presence of human serum, robust GFP expression was observed. This expression was completely abrogated if the human serum was heat-inactivated. Addition of purified human C1q protein to the heat-inactivated serum restored GFP expression. Similar results were seen when human C1q protein was added to purified anti-hexon antibodies, but not to anti-fiber or anti-penton base antibodies, thus implicating anti-hexon antibodies as the infective antibody component of the human sera. These studies suggest that complement protein C1q and anti-hexon antibodies together can mediate efficient adenovirus infection in CAR-negative cell types.
authors.affiliation: Department of Pharmacology, Canji Inc., San Diego, California, USA.
authors.forename: Van
authors.initials: V
authors.lastname: Tsai
authors.forename: Robin
authors.initials: R
authors.lastname: Varghese
authors.forename: Sundari
authors.initials: S
authors.lastname: Ravindran
authors.forename: Robert
authors.initials: R
authors.lastname: Ralston
authors.forename: Gary
authors.initials: G
authors.lastname: Vellekamp
mesh_terms: D000258:Adenovirus Infections, Human / Q000276:immunology* / Q000821:virology; D000260:Adenoviruses, Human / Q000276:immunology*; D000914:Antibodies, Viral / Q000276:immunology / Q000302:isolation & purification; D036022:Capsid Proteins / Q000276:immunology* / Q000302:isolation & purification; D015922:Complement C1q / Q000276:immunology*; D062727:Coxsackie and Adenovirus Receptor-Like Membrane Protein; D006367:HeLa Cells; D006801:Humans; D011991:Receptors, Virus / Q000276:immunology*; D012208:Rhabdomyosarcoma / Q000276:immunology / Q000821:virology*
chemical_list: D000914:Antibodies, Viral; C568771:CLMP protein, human; D036022:Capsid Proteins; D062727:Coxsackie and Adenovirus Receptor-Like Membrane Protein; D011991:Receptors, Virus; C018315:hexon capsid protein, Adenovirus; D015922:Complement C1q