Targeting and stimulation of the zebrafish (Danio rerio) innate immune system with LPS/dsRNA-loaded nanoliposomes

Abstract

Herein we report the use of immunostimulant-loaded nanoliposomes (called NLcliposomes) as a strategy to protect fish against bacterial and/or viral infections. This work entailed developing a method for in vivo tracking of the liposomes administered to adult zebrafish that enables evaluation of their in vivo dynamics and characterisation of their tissue distribution. The NLc liposomes, which co-encapsulate poly(I:C) and LPS, accumulate in immune tissues and in immunologically relevant cells such as macrophages, as has been assessed in trout primary cell cultures. They protect zebrafish against otherwise lethal bacterial (Pseudomonas aeruginosa PAO1) and viral (Spring Viraemia of Carp Virus) infections regardless of whether they are administered by injection or by immersion, as demonstrated in a series of in vivo infection experiments with adult zebrafish. Importantly, protection was not achieved in fish that had been treated with empty liposomes or with a mixture of the free immunostimulants. Our findings indicate that stimulation of the innate immune system with co-encapsulated immunostimulants in nano-liposomes is a promising strategy to simultaneously improve the levels of protection against bacterial and viral infections in fish.

Exploring the efficacy of vaccine techniques in juvenile sablefish,Anoplopoma fimbria

“…For example, Ruyra et al. () successfully encapsulated lipopolysaccharide (LPS) within a liposome to produce an efficacious immersion vaccine in zebrafish, Danio rerio , against a gram‐negative bacteria Pseudomonas aeruginosa . Ruyra et al.…”

“…Ruyra et al. () also determined that empty liposomes and unassociated LPS were not efficacious against the pathogen.…”

Nanostructured recombinant cytokines: A highly stable alternative to short-lived prophylactics

“…Adult zebrafish (0.64 ± 0.17 g body weight) were transferred to an isolated system and acclimatized 1 day before each experiment. Pseudomonas aeruginosa (PAO1) was cultured and grown as previously described [33]. Two different cytokines, CCL4 and TNFα, were successfully produced in E. coli as IBs ( Figure 1A).…”

Zebrafish liver (ZFL) cells are able to mount an anti-viral response after stimulation with Poly (I:C)

“…In addition, more recently, it has also become a model for those researchers working in fish immunology and vaccinology (Phelps and Neely, 2005;Boltana et al, 2013;Garcia-Valtanen et al, 2013Varela et al, 2014). We (Ruyra et al, 2014) and others have shown that zebrafish is an excellent model to study bioactive compounds prior to performing more laborious and expensive analysis in commercial species. Although zebrafish use is growing in many laboratories to replace the use of rodents or commercial fish species, there is a lack of wellcharacterised zebrafish in vitro models.…”