Downloaded from www.microbiologyresearch.org by IP: 54.70.40.11 On: Sun, 25 Nov 2018 01:35:11 An engineered avian-origin influenza A virus for pancreatic ductal adenocarcinoma virotherapy Matteo Samuele Pizzuto, 1 Micol Silic-Benussi, 2 Vincenzo Ciminale, 2 Ruth A. Elderfield, 1 Ilaria Capua 3 and Wendy S. Barclay 1 Correspondence Wendy S. Barclay w.barclay@imperial.ac.uk Received 31 May 2016 Accepted 12 July 2016 1 Imperial College London, Faculty of Medicine, Division of Infectious Disease, 8 Norfolk Place, London W2 1PG, UK 2 Department of Surgery, Oncology and Gastroenterology, University of Padua, Padua, Italy 3 OIE/FAO and National Reference Laboratory for Avian Influenza A Virus, Istituto Zooprofilattico Sperimentale delle Venezie, Padua, Italy Pancreatic ductal adenocarcinoma (PDA) is one of the leading causes of cancer-related deaths worldwide and the development of new treatment strategies for PDA patients is of crucial importance. Virotherapy uses natural or engineered oncolytic viruses (OVs) to selectively kill tumour cells. Due to their genetic heterogeneity, PDA cells are highly variable in their permissiveness to various OVs. The avian influenza A virus (IAV) H7N3 A/turkey/Italy/2962/03 is a potent inducer of apoptosis in PDA cells previously shown to be resistant to other OVs (Kasloff et al., 2014), suggesting that it might be effective against specific subclasses of pancreatic cancer. To improve the selectivity of the avian influenza isolate for PDA cells, here confirmed deficient for IFN response, we engineered a truncation in the NS1 gene that is the major virus- encoded IFN antagonist. The recombinant virus (NS1-77) replicated efficiently in PDA cells, but was attenuated in non-malignant pancreatic ductal cells, in which it induced a potent IFN response that acted upon bystander uninfected cancer cells, triggering their death. The engineered virus displayed an enhanced ability to debulk a PDA-derived tumour in xenograft mouse model. Our results highlight the possibility of selecting an IAV strain from the diverse natural avian reservoir on the basis of its inherent oncolytic potency in specific PDA subclasses and, through engineering, improve its safety, selectivity and debulking activity for cancer treatment. INTRODUCTION Pancreatic ductal adenocarcinoma (PDA) is considered as one of the most lethal malignancies in humans. Late detec- tion, early metastases, difficult surgical approach and resistance to chemotherapy all contribute to one of the worst prognoses among the various gastrointestinal cancers with a 5-year survival rate of merely 6 % (American Cancer Society, 2013). Development of new treatment strategies for patients suffering from PDA is an urgent necessity. Pancreatic cell carcinogenesis develops through accumula- tion of a characteristic set of mutations and genetic lesions which lead to activation of oncogenes and inactivation of tumour suppressor genes (KRAS, CDKN2A, TP53 and SMAD4/DPC4) (Bardeesy & DePinho, 2002). A hetero- geneous collection of secondary genetic alterations is also present in patients with pancreatic cancer (Biankin et al., 2012; Yachida & Iacobuzio-Donahue, 2013), giving rise to various PDA subclasses, reflected in a variety of cancer- derived cell lines (Deer et al., 2010), which may display dif- ferent therapeutic responsiveness and thus may require ad hoc intervention strategies (Biankin et al., 2012; Collisson et al., 2011). Virotherapy is a treatment based on oncolytic viruses (OVs) that exploit the genetic aberrations in tumours to selectively or preferentially infect, replicate and ultimately kill cancer cells whilst exerting minor or no effect on the surrounding healthy cells (Russell et al., 2012). The trans- lational impact of this technique has been further strength- ened by the approval of the adenovirus H101 for the treatment of head and neck cancer patients in China (Garber, 2006), by the registration of the ECHO-7 virus The sequences of all eight influenza genome segments belonging to H7N3 A/turkey/Italy/2962/2003 were previously submitted to Gen- Bank and assigned accession numbers JX515660, JX515661, JX515662, JX515663, JX515664, JX515665, JX515666, DQ090062. 2166 000549 ã 2016 The Authors Printed in Great Britain Journal of General Virology (2016), 97, 2166–2179 DOI 10.1099/jgv.0.000549