Phages in Therapy and Prophylaxis of American Foulbrood – Recent Implications From Practical Applications

Abstract

American foulbrood is one of the most serious and yet unsolved problems of beekeeping around the world, because it causes a disease leading to the weakening of the vitality of honey bee populations and huge economic losses both in agriculture and horticulture. The etiological agent of this dangerous disease is an extremely pathogenic spore-forming bacterium, Paenibacillus larvae , which makes treatment very difficult. What is more, the use of antibiotics in the European Union is forbidden due to restrictions related to the prevention of the presence of antibiotic residues in honey, as well as the global problem of spreading antibiotic resistance in case of bacterial strains. The only available solution is burning of entire bee colonies, which results in large economic losses. Therefore, bacteriophages and their lytic enzymes can be a real effective alternative in the treatment and prevention of this Apis mellifera disease. In this review, we summarize phage characteristics that make them a potentially useful tool in the fight against American foulbrood. In addition, we gathered data regarding phage application that have been described so far, and attempted to show practical implications and possible limitations of their usage.

Isolation and Characterization of Phages Active against Paenibacillus larvae Causing American Foulbrood in Honeybees in Poland

“…Phage application in apiaries in vivo should be preceded by their detailed characterization (phage activity, lytic spectrum, life cycle parameters, genome sequences, phage stability under expected conditions at the site of application or infection) and testing of their effectiveness in vitro as stated by Jończyk-Matysiak et al (2020) [ 23 ]. Our phages have been characterized and described (as shown in Figure 12 ) before we decided to choose phages for the final preparation composition.…”

“…The development of an effective and safe method for the prevention and control of AFB is highly desirable. Bacteriophages may be a promising solution in this area [ 22 , 23 ]. These bacterial viruses have proven to be common in the hive environment [ 22 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 ] and participate in bee gut microbiota [ 34 ], modulating its structure as well as influencing honeybee health [ 35 ].…”

“…Published data regarding this topic have been scant and have indicated that the specific isolated phages showed the ability to lyse only the vegetative forms of P. larvae strains, and in vivo effects have suggested that phages could be particularly useful in AFB prevention rather than treatment [ 30 , 39 ], whereas current data suggest that P. larvae phages may also bind to vegetative and spore forms of host bacteria, and binding spores may be reversible, which has been suggested as having great potential in the treatment of infection caused by sporulating bacteria [ 40 ]. Further research on the practical application of P. larvae phages regarding, e.g., different phage titers, different phage formulation compositions, forms of preparation, application mode, and addition of carriers both in vitro and in vivo during different stages of bee development are urgently needed [ 23 ].…”

Frontiers in effective control of problem parasites in beekeeping

“…This extends to beekeeping, where phages targeting either EFB or AFB (foulbrood bacteria) are being explored as alternative treatment methods for these sporadically problematic bacteria. Focus has principally been on the prevention of AFB outbreaks ( Brady et al, 2017 ; Yost et al, 2016 ) recently reviewed by Jończyk-Matysiak et al (2020) and Tsourkas (2020) with newer developments from Brady et al (2021) . While these treatments show some initial promise, their adoption will depend on whether current patterns of prophylactic treatment being more effective than responsive treatment remain true, and if so, what the regulatory and economic prospects (see section 4.1 & 4.2) of application of these methods for a fairly low-problem bacterial disease will be.…”

Fructose and Trehalose Selectively Enhance In Vitro Sporulation of Paenibacillus larvae ERIC I and ERIC II Strains

“…The breeding of resistant lines represents another way (besides antibiotic treatment and colony burnings) to control AFB and its sense has been shown by breeding colonies with hygienic behaviour [ 30 , 32 , 33 ]. Moreover, the possible use of different natural substances and probiotic bacteria for the prevention and control of AFB has been widely studied (reviewed in [ 34 , 35 ]), as well as employing bacteriophages for AFB prevention or treatment (reviewed in [ 36 ]).…”