Prophages, a type of phage that integrates into and remains in a bacterial genome, play an important role in the genomic diversification and fitness cost of bacteria to the infected host. As a class of genetic elements, some prophages can
Prophages, a type of phage that integrates into and remains in a bacterial genome, play an important role in the genomic diversification and fitness cost of bacteria to the infected host. As a class of genetic elements, some prophages can mediate horizontal gene transfer in the evolution of bacterial genomes (Lang, Zhaxybayeva & Beatty, 2012). Because they carry virulence genes, some prophages make outstanding contributions to bacterial pathogenesis (Penadés et al., 2015) and some have also contributed to the fitness cost of bacteria to the infected host (Fan et al., 2013). Therefore, it is essential to search for the presence of prophages in the bacterial genomes and to analyze them. To date, studies have identified prophages in a diverse range of hosts, such as Moraxella catarrhalis (Ariff et al., 2015), Lawsonia intracellularis (Vannucci, Kelley & Gebhart, 2013), Bifidobacterium spp. (Lugli et al., 2016; Ventura et al., 2009), Lactococcus spp. (Ventura et al., 2007), Mycobacterium spp. (Fan, Abd Alla & Xie, 2015; Fan et al., 2014), Streptococcus spp. (Tang et al., 2013), and some plant-pathogenic bacteria (Varani et al., 2013). However, a systemic investigation of genomic information and function of Helicobacter prophages is largely lacking.
Helicobacter is a genus of Gram-negative bacteria, most frequently found in the upper gastrointestinal tract of mammals. One well-