Researchers from the National University of Singapore (NUS) have developed an oral vaccine aimed at protecting farmed fish from nervous necrosis virus (NNV), a major threat to aquaculture production.
The vaccine can be delivered through feed, offering fish farming operators a practical alternative to injection-based vaccination methods.
“Fish are particularly vulnerable in the larval and juvenile stages, with the disease having a near 100 per cent mortality rate in the larval stage. Moreover, the growth is reduced even if some fish survive,” said Professor Yang Daiwen from the NUS Department of Biological Sciences.
”At present, there are no simple and effective treatments available for NNV infection, making prevention through vaccination the most promising strategy. Our novel discovery of a viable and effective delivery system to transport virus-like particles to enable fish to resist the effects of NNV addresses this pertinent issue.”
Disease protection
Developed in collaboration with Temasek Life Sciences Laboratory, the technology is designed to improve disease protection in juvenile fish while reducing handling stress and labour demands in commercial aquaculture operations.
According to the research team, the oral vaccine uses harmless bacteria to carry virus-like particles safely through the digestive system, allowing fish to develop immunity against NNV.
Trials showed that vaccinated fish produced significantly higher antibody levels and lower viral loads compared with fish receiving unprotected vaccine particles.
NNV is considered one of the most damaging viral diseases affecting aquaculture globally, particularly in species such as grouper and Asian seabass.
Existing injection-based vaccines are difficult to use on small fish, creating challenges for large-scale fish farming operations seeking efficient disease prevention measures.
The researchers said the oral vaccine could support more sustainable aquaculture production by improving fish survival rates and reducing losses linked to disease outbreaks.
They have filed patents for the technology and plans to conduct further field testing with industry partners.
