Temporal distribution of encapsulated bacteriophages during passage through the chick gastrointestinal tract

Abstract

Encapsulation of bacteriophages ("phage") protects phage against environmental deactivation and provides a product that is easy to handle for storage and application with animal feed as an antibiotic alternative. The objective of this study was to evaluate an orally administered, encapsulated phage for efficient phage release in the gastrointestinal tract (GIT) of young chicks receiving feed. An optimized formulation that consisted of 0.8% low molecular weight (MW) alginate, 2% ultra-low molecular weight alginate and 3% whey protein completely released the encapsulated phage within 60 min under simulated intestinal conditions. This product was given to broiler chicks to determine passage time and distribution of the viable phage within the GIT. Following a single oral dose of 10 plaque-forming unit (PFU)/chick, the major portion (peak concentration) of the encapsulated phage passed through the chick's GIT and was detected in the feces within 4 h, with low levels being continuously excreted for up to 24 h. In comparison, the passage of free phage through the GIT occurred faster as indicated by a peak concentration in feces after 1.5 h. In assessing the temporal phage distribution, both encapsulated and free phage treatments showed no apparent difference, both having low levels of 10 to 10 PFU/g of contents along the entire GIT after 1, 2 and 4 h. These low concentrations recovered in vivo led us to examine various exposure conditions (with feed, fecal material, and buffer solutions) that were suspected to have affected phage viability/infectivity during oral delivery, sample recovery, and enumeration by plaque assay. Results showed that the exposure conditions examined did not significantly reduce phage viability and could not account for the observed low phage levels following oral administration in chicks that are on feed. In conclusion, an oral encapsulated phage dose can take more than 4 h to completely move through the GIT of young chicks. Thus, repeated or higher doses may be necessary to attain higher phage concentrations in the GIT.

The Yersinia Phage X1 Administered Orally Efficiently Protects a Murine Chronic Enteritis Model Against Yersinia enterocolitica Infection

“…Currently, encapsulation of phages by liposomes (Colom et al, 2015) or alginate nanoparticles (Ma et al, 2016) may also be used to enhance bacteriophage stability and bactericidal activity. The pH in the stomach of mice is 3.0 (fed) and 4.0 (starved) (McConnell et al, 2008).…”

Transient carriage and low-level colonization of orally administrated lytic and temperate phages in the gut of mice

“…Ma et al (2016) demonstrated that the transient carriage of phage through the gastrointestinal tract of chickens occurred as indicated by a peak phage concentration in feces after 1.5 h. In the current study, we assessed the colonization of the gastrointestinal tract of mice by phages after oral administration with ad libitum access to water for 31 days. The limited phage colonization of the mouse gut matched data reported by Ma et al (2016), who assessed the temporal distribution of both encapsulated and free phages administered to young chicks, showing that both types of phages were present at levels ranging from 10 2 to 10 6 PFU/g of gut contents along the entire gastrointestinal system. Low-level phage colonization in the small intestine of treated mice could be due to the segmented movement of gut contents or the absence of their host bacteria.…”

Microencapsulation of Enteric Bacteriophages in a pH-Responsive Solid Oral Dosage Formulation Using a Scalable Membrane Emulsification Process

“…Liquid phage formulations taken orally exposes phages to stomach acidity and digestive tract contents (enzymes such as pepsin and pancreatin), increasing the risk of phage viability loss [16]. A recent in vivo study in chickens showed a significant reduction (3 log reductions compared to the dose given) in viable phages reaching the gastrointestinal tract due to stomach acid exposure [17]. Mice receiving an oral dose (T4 coliphages in drinking water) of 10 9 PFU/g gut contents had a thousand-fold lower phage titer, indicating a sizable loss in phage activity [16].…”

“…There is a clear need to protect phages against adverse gastrointestinal environmental conditions and to control their targeted release at the site of infection such as in the lower gastrointestinal tract (GIT) compartments of the cecum and colon for E. coli infections; this is achievable through encapsulation [19,20,22]. Microencapsulated phages may also result in longer transit times through the GIT in comparison with application of free phages due to mucoadhesive interactions with the gastrointestinal mucus [23] or in animals such as chickens, where retention of microparticles in the crop may result in slowing their transit through the GIT [17]. The purpose of encapsulation is to protect phages from harsh environmental stresses found in the gastrointestinal tract as well as to protect the phages during processing and storage prior to use [24], whilst yielding a product that is easy to handle and apply, e.g., with animal feed [17].…”

“…Microencapsulated phages may also result in longer transit times through the GIT in comparison with application of free phages due to mucoadhesive interactions with the gastrointestinal mucus [23] or in animals such as chickens, where retention of microparticles in the crop may result in slowing their transit through the GIT [17]. The purpose of encapsulation is to protect phages from harsh environmental stresses found in the gastrointestinal tract as well as to protect the phages during processing and storage prior to use [24], whilst yielding a product that is easy to handle and apply, e.g., with animal feed [17].…”