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Fiber mediated receptor masking in non-infected bystander cells restricts adenovirus cell killing effect but promotes adenovirus host co-existence
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2009 (English)In: PloS one, ISSN 1932-6203, Vol. 4, no 12, e8484- p.Article in journal (Refereed) Published
Abstract [en]

The basic concept of conditionally replicating adenoviruses (CRAD) as oncolytic agents is that progenies generated from each round of infection will disperse, infect and kill new cancer cells. However, CRAD has only inhibited, but not eradicated tumor growth in xenograft tumor therapy, and CRAD therapy has had only marginal clinical benefit to cancer patients. Here, we found that CRAD propagation and cancer cell survival co-existed for long periods of time when infection was initiated at low multiplicity of infection (MOI), and cancer cell killing was inefficient and slow compared to the assumed cell killing effect upon infection at high MOI. Excessive production of fiber molecules from initial CRAD infection of only 1 to 2% cancer cells and their release prior to the viral particle itself caused a tropism-specific receptor masking in both infected and non-infected bystander cells. Consequently, the non-infected bystander cells were inefficiently bound and infected by CRAD progenies. Further, fiber overproduction with concomitant restriction of adenovirus spread was observed in xenograft cancer therapy models. Besides the CAR-binding Ad4, Ad5, and Ad37, infection with CD46-binding Ad35 and Ad11 also caused receptor masking. Fiber overproduction and its resulting receptor masking thus play a key role in limiting CRAD functionality, but potentially promote adenovirus and host cell co-existence. These findings also give important clues for understanding mechanisms underlying the natural infection course of various adenoviruses.

Place, publisher, year, edition, pages
2009. Vol. 4, no 12, e8484- p.
URN: urn:nbn:se:umu:diva-42372DOI: 10.1371/journal.pone.0008484PubMedID: 20041185OAI: diva2:409147
Available from: 2011-04-07 Created: 2011-04-07 Last updated: 2011-04-07Bibliographically approved
In thesis
1. Mechanisms involved in adenovirus binding to and infection of host cells
Open this publication in new window or tab >>Mechanisms involved in adenovirus binding to and infection of host cells
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The adenovirus (Ad) family consists of 52 different human types, which are divided into seven species (A-G). Human Ads cause disease in the respiratory tract, lymphoid tissue, intestine, urinary tract, and/or in the eye. Most, but not all Ads have been demonstrated to use the coxsackie-adenovirus receptor (CAR) as an efficient receptor in vitro, but CAR has been questioned as an in vivo-receptor for various reasons. Thus, there are reasons to believe that Ads use other mechanisms for binding to target cells. In an attempt to investigate the impact of tear fluid during in vitro infection of ocular Ads (i.e. Ad37), using corneal cells, we found that human tear fluid promoted infection of an Ad with pronounced respiratory tropism (i.e. Ad5) used here as a control, but surprisingly not of Ad37. Furthermore using a virus overlay protein blotting assay we found that Ad5 bound to several tear fluid proteins. One of these, human lactoferrin (hLf) which is a component that belongs to the innate immune system in various body fluids, was alone able to promote both binding and infection of all species C Ads (Ad1, Ad2, Ad5, Ad6) in epithelial cells. hLf was also found to promote gene delivery (GFP) from an Ad5-based vector. Further we have identified lactoferricin (Lfcin), the N-terminal part of hLf, as to be responsible for this effect. We also show that plasma, saliva, and tear fluid promote infection of Ad5 in respiratory and ocular epithelial cells, and that plasma promotes infection of Ad31. The component in plasma that is responsible for this effect is likely to be coagulation factor IX (FIX) and X (FX), since both these factors were able to promote binding and infection of Ad5 and/or Ad31 in epithelial cells. Finally, we show that the excess of fiber production from initial Ad infection and the release of fibers before the particle itself is released caused masking of the tropism-specific receptors in both infected and non-infected surrounding cells. This means that the overproduction of fibers affects the ability of Ad to spread within tissues.

We conclude that soluble components in body fluids, such as hLf, FIX, and FX have the ability to mediate binding and infection of selected human Ads (species C and Ad31) in epithelial cells that represent the tropism of these Ads. We suggest that these components may serve as bridges between the virion and the cell surface. This is contributes to the knowledge about Ad lifecycle, and might help to improve the de-/retargeting of gene therapy based on Ad vectors.

Place, publisher, year, edition, pages
Umeå: Umeå university, 2009. 71 p.
Umeå University medical dissertations, ISSN 0346-6612 ; 1301
Adenovirus, binding, infection, lactoferrin, coagulation factor IX and X, fiber
National Category
Medical and Health Sciences
urn:nbn:se:umu:diva-27646 (URN)978-91-7264-876-0 (ISBN)
Public defence
2009-12-04, Betula, Byggnad 6M, NUS, Umeå, 09:00 (English)
Available from: 2009-11-16 Created: 2009-11-12 Last updated: 2011-04-07Bibliographically approved

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