In a study published in ACS Nano, researchers from MIT and the U.S. Department of Agriculture describe a new vaccination system for farmed fish using silk microneedles coated with shellac. The microneedles are designed to pierce fish skin underwater, release vaccines in a controlled manner, then decompose, and could offer a safer, more efficient approach to traditional needle injection.
Aquaculture is an increasingly important source of food around the world, with farmed aquatic animals exceeding wild-caught aquatic animals for the first time in 2021 by weight. But disease outbreaks can cause substantial losses, and while vaccines are used, delivering them effectively has been a challenge.
Current methods range from medicated feed and water immersion to manual needle injection. Needle vaccination is the most effective, but it has several downsides. Meng Li, an MIT postdoc and first author of the study, explains that workers inject fish one by one, describing it as “high intensity, there's a risk of cross contamination of blood-borne diseases, and workers may accidentally jab themselves because they are working so quickly.”
The new system uses microneedles made of silk fibroin, coated with a thin layer of shellac to make them water-resistant. After piercing the fish's skin, the microneedles stay attached as the fish swims and release vaccines over a controlled period. Li said some versions could release the vaccine within 15 minutes, while others could last 10 or even 24 hours.
The researchers showed the microneedles can store a range of vaccines and preserve half of DNA plasmids' structure after four weeks in dry conditions. Benedetto Marelli, a professor at MIT, said this stability is important “particularly for the last mile of delivery, because aquaculture is mostly done in rural areas.”
In tests on rainbow trout, the researchers showed the microneedles could deliver vaccines to fish as small as 1 to 2 grams, while traditional needle-based vaccination does not work well until fish reach about 30 grams. “In trout aquaculture, one of the biggest challenges we face is preventing disease early in a fish's life,” said Gregory Wiens, a USDA researcher. “What our research shows is food-grade silk fibroin microneedles can deliver vaccines underwater to fish as small as 1 to 2 grams.”
The team stresses that more work is needed before the technology can be used at scale in fish farms. But Marelli said: "There are so many challenges with aquaculture and fish vaccination right now. We need to support farmers to operate safely, improve working conditions, protect their business, make vaccination more accessible, and improve the living conditions of farmed fish."
Analysis
Why This Matters
- With global population growth and increasing demand for protein, aquaculture is becoming more important; improving vaccination could reduce disease losses and improve food security.
- The new method could make fish vaccination safer for workers by eliminating needle accidents, and less stressful for fish by avoiding sedation and handling.
- It allows vaccination of much smaller fish, potentially protecting fish earlier and improving overall health in aquaculture.
Background
Aquaculture is a major and growing source of food worldwide. In 2021, for the first time, farmed aquatic animals exceeded wild-caught ones by weight. Disease outbreaks can cause substantial losses, so farmers use vaccines. Current vaccination methods include medicated feed, immersion, and needle injection. Needle injection is most effective but requires sedating fish and manual handling, which is stressful for fish and dangerous for workers. MIT researchers previously developed silk microneedles for delivering nutrients to plants, and adapted them for fish vaccination.
What to Watch
- Further development and testing of the technology in commercial fish farms.
- Potential expansion to other fish species and types of vaccines.
- Steps toward regulatory approval and scalability for widespread use.
Checked
11 claims in this story checked against 1 source: 10 supported.
Show each claim
- SupportedMIT and USDA researchers developed silk microneedles for safer fish vaccination.MIT News: “a team of researchers at MIT and the U.S. Department of Agriculture has developed a potentially better way to deliver vaccines. The approach uses water-resistant, food-grade microneedles”
- SupportedWater-resistant, food-grade microneedles could offer a safer way to vaccinate farmed fish.MIT News: “The approach uses water-resistant, food-grade microneedles that can lightly penetrate and remain attached to fish skin before decomposing.”
- SupportedThe researchers described the system in a study published in ACS Nano.MIT News: “In a new paper published in ACS Nano , the researchers described their system”
- Partly supportedLi said workers inject fish one by one, calling the work “high intensity, there's a risk of cross contamination of blood-borne diseases, and workers may accidentally jab themselves because they are working so quickly.”MIT News: ““Workers inject fish one by one,” Li explains. “It’s high intensity, there’s a risk of cross contamination of blood-borne diseases, and workers may accidentally jab themselves because they are working so quickly.”
- SupportedThe microneedles use silk fibroin coated with a thin layer of shellac to make them water-resistant.MIT News: “The system described in the new paper uses a thin layer of shellac, an insect-secreted resin used in food coating and pills, to make silk microneedles water-resistant”
- SupportedThe microneedles can stay attached as fish swim and release vaccines in a controlled way.MIT News: “We designed these single‑use microneedles to pierce wet skin, stay attached while the fish swim, and release either bacterin or DNA vaccines in a controlled way.”
- SupportedSome versions could release vaccine within 15 minutes, while others could release it over 10 or 24 hours.MIT News: ““In some cases, you may want the vaccine released within 15 minutes, but in others, the release can last 10 or even 24 hours,” Li says.”
- SupportedThe microneedles preserved half of DNA plasmids’ structure after four weeks in dry conditions.MIT News: “The microneedles were also able to preserve half of the DNA plasmids’ structure when stored for four weeks in dry conditions.”
- SupportedFarmed aquatic animals exceeded wild-caught aquatic animals in global food production by weight for the first time in 2021.MIT News: “In 2021, for the first time, farmed aquatic animals exceeded wild-caught aquatic animals in global food production by weight.”
- SupportedIn rainbow trout tests, the microneedles delivered vaccines to fish as small as 1 to 2 grams; traditional needle vaccination does not work well until fish reach about 30 grams.MIT News: “traditional needle‑based vaccination just doesn’t work well until the fish reach about 30 grams, which leaves the smallest juveniles unprotected during a critical growth period,” says Wiens. “What our research shows is food‑grade silk fibroin microneedles can deliver vaccines underwater to fish as small as 1 to 2 grams.”
- SupportedThe technology needs further work before it can be used at scale in fish farms.MIT News: “The researchers say there is still work to be done before their device can be seamlessly used at scale in fish farms.”
