Aquaculture is one the most proliferative agriculture industry owing to the increasing demand for fish products and decreasing wild catch. However, with intensive aquaculture, where stocks are kept in high density, microbial diseases would often emerge and result in outbreaks leading to massive deaths. In the past antibiotics are used to treat the infections. But, due to its misuse, resistant microbes have emerged and are now rampant in killing stocks. As a result, vaccines are very much preferred and are usually administered via a needle injection into the fish when they are at least ≥10g in size. Fish <10g are dip vaccinated—vaccine being mixed in water and fish exposed briefly in the mixture. Despite being dip vaccinated, many fish still die of disease due to the poor uptake efficiency of the vaccine. This led to the development of a nanovaccine composition that could effectively deliver vaccines into fish <10g in size. This nanovaccine, comprises of nano-needles which can be filled with antigens (proteins) but, it could also be used to deliver other materials such as hormones, nutrients, minerals, antibiotics or even chemicals into aquatic animals.
Technology Features, Specifications and Advantages
The nanovaccine has been demonstrated to deliver its payload, such as proteins like GFP, into the skin, gills and gut of fish, and is composed of 3 major components:
- Nanomaterial—Halloysite clay (HC). Chosen through a mass toxicity screening of several nanomaterials, which found HC to be safe for use in fish and mammalian cells (i.e. no acute toxicity response).
- Capping agent—Chitosan. A linear polysaccharide composed of randomly distributed β-(1→4)-linked D-glucosamine (deacetylated unit) and N-acetyl-D-glucosamine (acetylated unit) obtained from the chitin shells of shrimp and other crustaceans. Chitosan is used in the preparation of the nanovaccine as it helps to form a tight attachment of the nanovaccine to the fish target tissues such as the skin, gills and the gut epithelium.
- Bacterial antigen (protein). Processed from a microbe, such as the outer membrane proteins of pathogenic bacteria (antigen), they are loaded into the hollow cavity of HC nanoparticles.
This nanomaterial assisted delivery and methodology is a platform technology which can be adapted for use in delivering antigens from bacteria, viruses and parasites. Other materials such as recombinant proteins or DNA, hormones, nutrients, minerals, antibiotics or even chemicals, can be incorporated into the nanomaterial for delivery into a large range of aquatic animals besides fish such as crustaceans like shrimps and crabs, and shellfish like cockles, mussels and oysters.
- Allows administration of vaccines via simple dipping/immersion
- Do not require skilled manpower to inject vaccines into fish
- Enables early protection in young fish, allowing them to reach maturity and market size
- Lower cost of production in the long run
- Increased overall productivity