Development of phage delivery by bioencapsulation of artemia nauplii with Edwardsiella tarda phage (ETP-1)

Abstract

This study proposed that phage-enriched artemia could be a useful tool for transferring phage into the cultured fish (larvae or adult) as a feed, and introduce mode of phage administration and its safety in concern of tissue adaptation for efficient phage therapy in aquatic animals. First, whether Edwardsiella tarda phage (ETP-1) could attach or ingest by the artemia and optimum time period for the ETP-1 enrichment with artemia were investigated. ETP-1 dispersion, abundance and persistency, and zebrafish immune transcriptional responses and histopathology were evaluated after feeding the fish with ETP-1-enriched artemia. Hatched artemia nauplii (36 h) were enriched with 1.90 × 10 11 PFUmL −1 of ETP-1, and maintained at 25°C. The highest enrichment level was obtained after 4 h (3.00 × 10 9 PFUmL −1), and artemia were alive and active similar to control for 8 h. ETP-1 disseminated dose dependently to all the tissues rapidly (12 h). However, when feeding discontinued, it drastically decreased at day 3 with high abundance and persistency in the spleen (1.02 × 10 3) followed by the kidney (4.00 × 10 1) and the gut (1 × 10 1 PFUmL −1) for highest ETP-1-enriched artemia dose. In contrast, during continuous delivery of ETP-1-enriched artemia, ETP-1 detected in all the tissues

Phage-Mediated Control of Flavobacterium psychrophilum in Aquaculture: In vivo Experiments to Compare Delivery Methods

“…Thus, a key step in delivering phages via feed is the application of very high initial titers. In a recent study, the delivery of Edwardsiella tarda phage ETP-1 bio-encapsulated in Artemia nauplii (enriched Artemia at 10 11 PFU ml –1 ) could provide phages with a concentration of 10 4 –10 6 PFU mg –1 of tissue 10 days after the start of the phage feeding in gut, kidney, spleen and liver of zebrafish ( Nikapitiya et al, 2020 ). Interestingly, it seemed that phage penetration from the gut into the circulatory system was very efficient and only a 10-fold phage decay was observed between the gut and the kidney at the time points examined.…”