Contents lists available at ScienceDirect Virus Research journal homepage: www.elsevier.com/locate/virusres Comparative genome analysis of novel Podoviruses lytic for hypermucoviscous Klebsiella pneumoniae of K1, K2, and K57 capsular types Ekaterina V. Solovieva, Vera P. Myakinina, Angelina A. Kislichkina, Valentina M. Krasilnikova, Vladimir V. Verevkin, Vladimir V. Mochalov, Anastasia I. Lev, Nadezhda K. Fursova, Nikolay V. Volozhantsev ⁎ State Research Center for Applied Microbiology and Biotechnology, Obolensk 142279, Moscow Region, Russia ARTICLE INFO Keywords: Bacteriophage Genome analysis Hypermucoviscosity Polysaccharide depolymerase ABSTRACT Hypermucoviscous (HV) strains of capsular types K1, K2 and K57 are the most virulent representatives of the Klebsiella pneumoniae species. Eight novel bacteriophages lytic for HV K. pneumoniae were isolated and char- acterized. Three bacteriophages, KpV41, KpV475, and KpV71 were found to have a lytic activity against mainly K. pneumoniae of capsular type K1. Two phages, KpV74, and KpV763 were lytic for K2 capsular type K. pneu- moniae, and the phage KpV767 was specific to K57-type K. pneumoniae only. Two more phages, KpV766, and KpV48 had no capsular specificity. The phage genomes consist of a linear double-stranded DNA of 40,395–44,623 bp including direct terminal repeats of 180–246 bp. The G + C contents are 52.3–54.2 % that is slightly lower than that of genomes of K. pneumoniae strains being used for phage propagation. According to the genome structures, sequence similarity and phylogenetic data, the phages are classified within the genus Kp32virus and Kp34virus of subfamily Autographivirinae, family Podoviridae. In the phage genomes, genes en- coding proteins with putative motifs of polysaccharide depolymerase were identified. Depolymerase genes of phages KpV71 and KpV74 lytic for hypermucoviscous K. pneumoniae of K1 and K2 capsular type, respectively, were cloned and expressed in Escherichia coli, and the recombinant gene products were purified. The specificity and polysaccharide-degrading activity of the recombinant depolymerases were demonstrated. 1. Introduction Bacterial viruses (bacteriophages or phages) are natural killers of bacteria that specifically infect and lyse bacterial host strains. Due to the bacteriolytic activity and bacterial host specificity, bacteriophages are considered as potential bioagents to control various pathogenic bacteria. Klebsiella pneumoniae is an opportunistic pathogen that is a common cause of healthcare-associated infections such as septicemia, pneu- monia, urinary tract infections, surgical site infections, and catheter- related infections (Chung, 2016; Podschun and Ullmann, 1998). The isolation of multidrug-resistant K. pneumoniae in hospitals is increas- ingly reported (Prestinaci et al., 2015). Over the past three decades, a new type of hypervirulent K. pneumoniae (hvKP) causing community- acquired invasive life-threatening infections characterized by pyogenic liver abscesses with possible dissemination to distant body sites has emerged worldwide, especially in the Asia-Pacific region (Fang et al., 2005; Liu et al., 1986; Shon et al., 2013; Sobirk et al., 2010; Turton et al., 2007). A hallmark of many hvKP strains is hypermucoviscosity (HV) that is associated with the overproduction of capsular poly- saccharides (CPS) and the presence of rmpA gene and/or its isoform rmpA2 encoding the transcriptional activators of CPS biosynthesis (Cheng et al., 2010; Hsu et al., 2011; Shon et al., 2013). Of more than 78 CPS-types K. pneumoniae, K1, and K2 (and to a lesser extent K5, K20, K54, and K57) strains overproducing capsular polysaccharides are the most virulent human pathogens (Fang et al., 2007; Liu et al., 2014; Yu et al., 2008). It is unclear whether all hypervirulent K. pneumoniae strains are hypermucoviscous. Nevertheless, it was shown that HV-po- sitive strains cause the distinctive invasive infections such as liver ab- scess, meningitis, pleural empyema or endophthalmitis rather than HV- negative strains (Lee et al., 2006). As determined by statistical multi- variate analysis, strains carrying rmpA gene are significantly associated with the HV-phenotype, and there is a significant correlation with purulent tissue infections including liver abscess and other focal ab- scesses (Yu et al., 2006). Our analysis of strains isolated in Russian hospitals between 2011 http://dx.doi.org/10.1016/j.virusres.2017.09.026 Received 1 July 2017; Received in revised form 29 September 2017; Accepted 30 September 2017 ⁎ Corresponding author at: Department of Molecular Microbiology, State Research Center for Applied Microbiology and Biotechnology, Obolensk 142279, Moscow Region, Russian Federation. E-mail address: nikvol@obolensk.org (N.V. Volozhantsev). Virus Research 243 (2018) 10–18 Available online 05 October 2017 0168-1702/ © 2017 Elsevier B.V. All rights reserved. MARK