A group of scientists in North America have developed a delivery system for an oral vaccine that could spell the end of disease-ravaged shrimp ponds and billions of dollars in lost harvests.
The solution US-based Pebble Labs has come up with uses what it refers to as “transbiotics”: essentially the production of double stranded ribonucleic acid (RNA) inside naturally occurring bacteria that are delivered to the shrimp and remain in their gut over the production cycle of the animal, protecting them from disease, Richard Sayre, the company’s chief scientific officer tells IntraFish.
Progress in global shrimp production is constantly hampered by the devastation of disease. Unpredictable and all-consuming, pathogens wipe out billions of dollars worth of shrimp every year.
White spot syndrome virus (WSSV) has long been a major player in this devastation, but according to Sayre, this system of delivery could well spell the end of the disease’s enormous impact.
RNA is naturally present in all living cells and its principal role is to act as a messenger carrying instructions from DNA for controlling the synthesis of proteins.
The RNA Pebble Labs uses is designed to target and deactivate genes that are essential for the target pathogen — in this initial case WSSV — to thrive in the host.
Trials have shown the system to reduce mortality in white spot-infected ponds from 45 to 100 percent.
At early stages of production, when the shrimp are filter feeding, the bacteria can be put into the water itself — “vaccination by immersion,” as Sayre puts it.
This is the ideal time for application, according to Sayre, but there is also nothing stopping the probiotic being added as a top coating on feed for adult shrimp.
The aim is that the application only need be made once at a low dose, the objective being to introduce the bacteria at the naupali stage, where it remains in the shrimp’s gut throughout its life cycle.
The probiotic has been through multiple trials. The first trials targeted one gene and the company is now moving into multi-gene trials that will target a wider range of pathogens.
Until now, the production of RNA was expensive, making it prohibitive in most agriculture applications. With transbiotics this is no longer an issue, as the RNA is produced by the bacteria at no cost, then grown in large-scale fermenters in sufficient quantities to cover the entire world’s shrimp production and more.
Once FDA-approved — the application process began started last month — the group will look to distribute the product via a partnership with some of the world’s bigger LP producers or with a major feed producer, Pebble Labs CEO Michael Harrison told IntraFish.
The group toured Southeast Asia and Australia last month and already has verbal agreements with several large Australian producers for trials, according to Harrison. Time to market for the WSSV solution will depend on FDA approval, but is expected to be around 18 months.
“This is a very safe and efficient way of protecting the shrimp,” said Harrison, emphasizing this “super probiotic” would negate the need for antibiotics by enabling immunity in the shrimp.
There is also no environmental impact that the company is aware of. RNA is already used in food crops and against mosquitos.
“In just a short time disease can cause billions of dollars of losses,” said Harrison.“If shrimp farmers can move the dial by single digits, it’s a game changer,” he said.
It’s a simple approach, explains Director of Regulatory Affairs, Kimberly Harrison. “The bacteria is introduced to the water and the shrimp absorbs, or consumes the bacteria naturally,” she said.
The RNA target can also be quickly updated to respond to resistance and the emergence of new diseases, by “slotting in” another gene sequence, according to Harrison.
The disease control applications for RNA interference are wide-ranging, from shrimp, fish, mosquitos and plants to potentially the issue of sea lice in salmon.
“There has been a very enthusiastic response from shrimp farmers because they have nothing else,” said Dr Anne Lo, Pebble Labs’ director of strategic development.
“They are used to losses, but here is an affordable solution.”
Original article here