Isolation and characterization of a N4-like lytic bacteriophage infecting Vibrio splendidus, a pathogen of fish and bivalves

Abstract

A novel virulent bacteriophage, vB_VspP_pVa5, infecting a strain of Vibrio splendidus was isolated from a sea-cage aquaculture farm in Greece, and characterized using microbiological methods and genomic analysis. Bacteriophage vB_VspP_pVa5 is a N4-like podovirus with an icosahedral head measuring 85 nm in length and a short non-contractile tail. The phage had a narrow host range infecting only the bacterial host, a latent period of 30 min and a burst size of 24 virions per infected bacterium. Its genome size was 78,145 bp and genomic analysis identified 107 densely-packed genes, 40 of which could be annotated. In addition to the very large virion encapsulated DNA-dependent RNA polymerase which is the signature of the N4-like genus, an interesting feature of the novel phage is the presence of a self-splicing group I intron in the thymidylate synthase gene. A tRNAStop interrupted by a ~2.5kb open reading frame–containing area was also identified. The absence of genes related to lysogeny along with the high efficacy observed during in vitro cell lysis trials, indicate that the vB_VspP_pVa5 is a potential candidate component in a bacteriophage cocktail suitable for the biological control of V. splendidus in aquaculture.

Phages associated with horses provide new insights into the dominance of lateral gene transfer in virulent bacteriophages evolution in natural systems

“…The G7-like phages The E. coli phage N4, the prototype species of the group of N4-related viruses was a database orphan for many years (Kazmierczak et al 2002). However, over the last decade, numerous N4-like viruses that infect Gram-negative bacteria were isolated and sequenced (Faidiuk et al 2017;Golomidova et al 2007;Cai et al 2015;Patel et al 2015;Li et al 2016;Ma et al 2016;Shigehisa et al 2016;Bhattacharjee et al 2017;Katharios et al 2017;Buttimer et al 2018), and for reviews see (Chan et al 2014;Wittmann et al 2015). The N4-related sequences are also ubiquitous in human fecal metagenomes and viromes (Waller et al 2014).…”

Isolation and Characterization of the Novel Phages vB_VpS_BA3 and vB_VpS_CA8 for Lysing Vibrio parahaemolyticus

“…Our results suggested that phages can be found in virtually all places where their related hosts exist. Several other investigations reported the presence of Vibrio-specific lytic phages in environmental water (shrimp ponds, aquaculture system, sea water and aquatic product market) from different regions of the world (Alagappan et al, 2010;Luo et al, 2016;Stalin and Srinivasan, 2016;Katharios et al, 2017;Srinivasan and Ramasamy, 2017;Yang M. et al, 2019).…”

A novel vibriophage exhibits inhibitory activity against host protein synthesis machinery

“…This study also elucidates that the phage is able to hijack protein translation machinery of the host bacteria. In comparison to other phages that infect vibrios (Table S2) [46][47][48][49][50][51][52] , phage Seahorse has relatively big burst size with a shorter latency period than phages VP-1, VP-2, VP-3, VpKK5, and VhKM4 that replicate in V. parahaemolyticus 27,29,[53][54][55][56] . It is also tolerant to the wide range of pHs and temperatures compared to other vibriophages suggesting unique survivability in harsh natural environments.…”

“…For pH stability, 100 μl of phage lysate was mixed with 900 μl of SM buffer in a pH range 2 to 10 and incubated at 30 °C for 1 hour. For temperature stability, 50 μl of phage lysate was incubated for 1 hour at different temperatures; 4,20,25,30,37,40,50,60, and 70 °C. For both tests, phage infectivity was determined by performing a spot test.…”