Syrian Hamster Tumor Model to Study Oncolytic Ad5-Based Vectors
Oncolytic (replicating) adenovirus (Ad) vectors are emerging as a promising form of a cancer therapy agent. There has been a need for an appropriate animal model to study oncolytic Ad since human Ad replication is usually species specific. We have shown
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Introduction Oncolytic adenovirus (Ad) vectors are under study as cancer therapy agents. A major obstacle in the oncolytic Ad field is the lack of a proper animal model to study these vectors. Because of the species specificity of Ads, such vectors are commonly evaluated in immunodeficient mice bearing human tumor xenografts. However, since these mice are immunodeficient and nonpermissive for human Ads, this model cannot adequately address the effect of the host immune system on the vector-infected tumor or the toxicity and biodistribution of the vector in normal tissues. We have developed a novel Syrian hamster model for the study of oncolytic Ad serotype 5 (Ad5)-based vectors because the hamsters are both immunocompetent and permissive David H. Kirn et al. (eds.), Oncolytic Viruses: Methods and Protocols, Methods in Molecular Biology, vol. 797, DOI 10.1007/978-1-61779-340-0_4, © Springer Science+Business Media, LLC 2012
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for human Ad5 (1). We have further used this model to study the effects of preexisting anti-Ad5 immunity (which is prevalent in the human population) on intratumoral vector efficacy (2) and the role of preexisting immunity and passive immunity in vector-associated toxicity (3). Additionally, we compared the hamster and the mouse models to determine the toxicity and biodistribution of Ad vectors following an intravenous (iv) injection of the vector (4, 5). We have also used Syrian hamsters to develop a pancreatic cancer model to study oncolytic Ads (6) and to study the effect of immunosuppression on oncolytic Ad vector antitumor efficacy (7). Since Syrian hamsters are permissive for Ad5 replication, they provided us with a very promising model to study anti-Ad drugs (8). Apart from our group, the Syrian hamster is also being used by other groups to study various Ad vectors (9–12). This chapter describes how to immunosuppress the hamster, generate preexisting immunity against Ad, and how to determine the anti-Ad5 neutralizing antibody (NAb) titers from various tissues. Additionally, we describe methods for establishing cell lines from Syrian hamster tumors, passaging transplantable tumors, ways to generate disseminated pancreatic tumors, and how to oral gavage a hamster. The handling, maintenance, and some basic techniques with Syrian hamsters have been described previously (13). We have used the Syrian hamster model to work primarily with Ad5-based vectors. We presume that the model would be useful for other Ad serotypes in Species C (Ad1, 2, 5, 6) because these serotypes are highly related to Ad5. In our experience, the Syrian hamster is not permissive, or is minimally permissive for human Ads that are not in Species C.
2. Materials 1. Syrian (golden) hamsters (Mesocricetus auratus), 4- to 5-weekold females (Harlan Sprague Dawley, Indianapolis, IN). 2. Dulbecco’s modified Eagle’s medium (DMEM). 3. Fetal bovine serum (FBS). 4. Trypsin–ethylenediaminetetraacetic acid (EDTA). 5. Virus: Purified and titered Ad5. 6. Human lung carcinoma cell line A549 [American Type Culture Collection
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