Animal vaccine reveals potential novel delivery for oral drugs
for badgers based on alginate gel beads, which protect the bacteria
from stomach acid until it reaches the intestine. They say the
technology could also work for human vaccines.
The project being carried out by Dr Perrie and co-reasearcher Dr Hannah Batchelor at Aston University was launched in an effort to remove the potential TB transmission route from badgers to cattle. Last year alone, over 20,000 cattle were slaughtered in the UK due to TB infection, at a cost of £31 million in farmer compensation.
The researchers have received funding from the Veterinary Licensing Agency to develop appropriate vaccines for badgers but it could work across a range of species, including man.
"If it works on badgers there is no reason why you couldn't scale it up to humans," Dr Yvonne Perrie told In-Pharmatechnologist.com.
"A significant problem in the oral delivery of vaccines is that the acid within the stomach of the badger destroys the fragile vaccine, thus it does not reach the intestines where it is absorbed.
"Our preliminary experiments have shown that the beads remain intact within a solution of acid (simulated gastric fluid) for up to two hours, after which the beads are transferred to simulated intestinal fluid where they are seen to fully dissolve over a two-hour period," said the researchers.
Alginates are natural products derived from seaweed and can be found in many food substances as well as pharmaceutical applications like excipients.
"This means there are no issues of toxicity and speeds up the lead-in time to development," said Dr Perrie.
"Alginate beads have most famously been used to encapsulate islet cells to create an artificial pancreas," added Dr Batchelor.
Batchelor has also been investigating the potential use of alginates to construct a kind of internal bandage that would coat the oesophagus, protecting it from stomach acid in gastrointestinal reflux.
"The beads can carry the TB bacteria, which is quite large, protecting it until it reaches the intestine where it accesses the lymph nodes. It has been tailored to deliver live attenuated bacteria, which need a mild protocol and are very fragile," explained Dr Perrie.
A similar approach has in fact been used to deliver live probiotic bacteria to the gut, she added.
The vaccine also had to act as a tempting bait, and the odourless alginate beads are expected to conform to the high compliance requirements of the badgers.
Humans too tend to be keener on oral vaccines however. "Oral drug delivery vaccines are a gold standard. An oral TB vaccine could be especially useful in developing countries where you could cut down on the associated health risks with injecting vaccines."
