Bacteriophage Interactions with Marine Pathogenic Vibrios: Implications for Phage Therapy

Abstract

A global distribution in marine, brackish, and freshwater ecosystems, in combination with high abundances and biomass, make vibrios key players in aquatic environments, as well as important pathogens for humans and marine animals. Incidents of Vibrio-associated diseases (vibriosis) in marine aquaculture are being increasingly reported on a global scale, due to the fast growth of the industry over the past few decades years. The administration of antibiotics has been the most commonly applied therapy used to control vibriosis outbreaks, giving rise to concerns about development and spreading of antibiotic-resistant bacteria in the environment. Hence, the idea of using lytic bacteriophages as therapeutic agents against bacterial diseases has been revived during the last years. Bacteriophage therapy constitutes a promising alternative not only for treatment, but also for prevention of vibriosis in aquaculture. However, several scientific and technological challenges still need further investigation before reliable, reproducible treatments with commercial potential are available for the aquaculture industry. The potential and the challenges of phage-based alternatives to antibiotic treatment of vibriosis are addressed in this review.

The Fate of Bacteriophages in Recirculating Aquaculture Systems (RAS)—Towards Developing Phage Therapy for RAS

“…At the time of the 'post-antibiotic era' declared by the WHO, interest towards sustainable tools that reduce the need for antibiotics is increasing. Phages infecting aquaculture pathogens such as Flavobacterium and Vibrio species have already been isolated [14,20,21].…”

“…However, it is also a vulnerable environment for outbreaks of infectious diseases. RAS has been considered to be an optimal environment for the use of phage therapy against bacterial diseases [14], but so far, phage distribution and stability have not been tested on these systems. Here we show that after a single phage addition, the phage can be re-isolated from the RAS units at a fish farm for up to three weeks.…”

“…It has also been applied to aquaculture related bacterial pathogens, experimentally, and in practice [12,13]. So far, there is no information about phage use in RAS, but this type of system can be considered an ideal environment for phage therapy applications [14]. The water recirculation process is an advantage for phage delivery since, in theory, phage would remain in the system for long time periods for being small enough to pass through filters and other barriers, recirculating freely with the water.…”

A novel vibriophage exhibits inhibitory activity against host protein synthesis machinery

“…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.…”

“…Bacteriophage therapy has been under a recent spotlight as an alternative therapeutic method that helps minimize the extensive use of antibiotics, delay the emergence of antibiotic resistance, and combat the existing MDR bacteria 23 . In aquaculture, phage application using various potent lytic phages has been proven successful in preventing vibriosis by V. harveyi, V. alginolyticus, V. coralliilyticus, V. anguillarum, V. cyclitrophicus, V. splendidus as well as V. parahaemolyticus 24,25 . During the past few years, many phages, such as VP882, Vp1, Vpms1, A3S, VpKK5, and VVP1, have been isolated from natural resources exhibiting potent antibacterial activity against V. parahaemolyticus 26 .…”