title: Manipulating adenovirus hexon hypervariable loops dictates immune neutralisation and coagulation factor X-dependent cell interaction in vitro and in vivo.
abstract: Adenoviruses are common pathogens, mostly targeting ocular, gastrointestinal and respiratory cells, but in some cases infection disseminates, presenting in severe clinical outcomes. Upon dissemination and contact with blood, coagulation factor X (FX) interacts directly with the adenovirus type 5 (Ad5) hexon. FX can act as a bridge to bind heparan sulphate proteoglycans, leading to substantial Ad5 hepatocyte uptake. FX "coating" also protects the virus from host IgM and complement-mediated neutralisation. However, the contribution of FX in determining Ad liver transduction whilst simultaneously shielding the virus from immune attack remains unclear. In this study, we demonstrate that the FX protection mechanism is not conserved amongst Ad types, and identify the hexon hypervariable regions (HVR) of Ad5 as the capsid proteins targeted by this host defense pathway. Using genetic and pharmacological approaches, we manipulate Ad5 HVR interactions to interrogate the interplay between viral cell transduction and immune neutralisation. We show that FX and inhibitory serum components can co-compete and virus neutralisation is influenced by both the location and extent of modifications to the Ad5 HVRs. We engineered Ad5-derived HVRs into the rare, native non FX-binding Ad26 to create Ad26.HVR5C. This enabled the virus to interact with FX at high affinity, as quantified by surface plasmon resonance, FX-mediated cell binding and transduction assays. Concomitantly, Ad26.HVR5C was also sensitised to immune attack in the absence of FX, a direct consequence of the engineered HVRs from Ad5. In both immune competent and deficient animals, Ad26.HVR5C hepatic gene transfer was mediated by FX following intravenous delivery. This study gives mechanistic insight into the pivotal role of the Ad5 HVRs in conferring sensitivity to virus neutralisation by IgM and classical complement-mediated attack. Furthermore, through this gain-of-function approach we demonstrate the dual functionality of FX in protecting Ad26.HVR5C against innate immune factors whilst determining liver targeting.
authors: Institute of Cardiovascular and Medical Sciences, BHF Glasgow Cardiovascular Research Centre, University of Glasgow, Glasgow, United Kingdom.
authors: Jiangtao
authors: J
authors: Ma
authors: Institute of Cardiovascular and Medical Sciences, BHF Glasgow Cardiovascular Research Centre, University of Glasgow, Glasgow, United Kingdom.
authors: Margaret R
authors: MR
authors: Duffy
authors: Institute of Cardiovascular and Medical Sciences, BHF Glasgow Cardiovascular Research Centre, University of Glasgow, Glasgow, United Kingdom.
authors: Lin
authors: L
authors: Deng
authors: Institute of Cardiovascular and Medical Sciences, BHF Glasgow Cardiovascular Research Centre, University of Glasgow, Glasgow, United Kingdom.
authors: Rachel S
authors: RS
authors: Dakin
authors: Crucell Holland BV, Leiden, The Netherlands.
authors: Taco
authors: T
authors: Uil
authors: Crucell Holland BV, Leiden, The Netherlands.
authors: Jerome
authors: J
authors: Custers
authors: Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom.
authors: Sharon M
authors: SM
authors: Kelly
authors: University of Surrey, Guildford, Surrey, United Kingdom.
authors: John H
authors: JH
authors: McVey
authors: Institute of Cardiovascular and Medical Sciences, BHF Glasgow Cardiovascular Research Centre, University of Glasgow, Glasgow, United Kingdom.
authors: Stuart A
authors: SA
authors: Nicklin
authors: Institute of Cardiovascular and Medical Sciences, BHF Glasgow Cardiovascular Research Centre, University of Glasgow, Glasgow, United Kingdom.
authors: Andrew H
authors: AH
authors: Baker
mesh_terms: D000258:Adenovirus Infections, Human / Q000276:immunology / Q000517:prevention & control; D000260:Adenoviruses, Human / Q000235:genetics / Q000276:immunology*; D000818:Animals; D057134:Antibodies, Neutralizing / Q000276:immunology; D000914:Antibodies, Viral / Q000276:immunology*; D000956:Antigens, Viral / Q000235:genetics / Q000276:immunology; D036022:Capsid Proteins / Q000235:genetics* / Q000276:immunology*; D045744:Cell Line, Tumor; D005170:Factor X / Q000276:immunology*; D014644:Genetic Variation / Q000235:genetics; D005822:Genetic Vectors / Q000235:genetics; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D007075:Immunoglobulin M / Q000097:blood / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D020349:Surface Plasmon Resonance; D014161:Transduction, Genetic; D053585:Virus Attachment
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D000956:Antigens, Viral; D036022:Capsid Proteins; D007075:Immunoglobulin M; C018315:hexon capsid protein, Adenovirus; D005170:Factor X