Vaccination effective in fish; can be extended to humans, says Fisheries College Dean

One of the harmful forms of bacterial growth may soon be used as an efficient way to counter infection.

At College of Fisheries here, researchers are developing a vaccination out of a bacterial ‘biofilm’, a tendency of bacteria to pile up on each other to form a layer that is resistant to certain conditions.

The research, funded by the International Foundation for Science in Sweden since 1993, has been published in peer-reviewed journals such as Fish and Shellfish Immunology and Journal of Aquaculture Tropics.

K.M. Shankar, Dean of the college, who is spearheading the research using the bacteria Aeromonas hydrophila - a pathogen of the common Indian carp, said though the process was effective in countering infections in fish, the concept can be applied to livestock, poultry and for delivering human medicine. Field trials may see the novel vaccination being developed within a year, he said.

The disease, which manifests itself as an ulcer and then leads to death, is now countered by “abuse” of antibiotics that lower the quality of the fish, Mr. Shankar said.

What is it

As fish breed in large numbers, it is impossible to vaccinate each one. Oral vaccination is the only technique to keep them disease-free. Currently, “free cell” inactive bacteria vaccination (the same concept is used in polio or Hepatitis vaccination) shows an efficiency of just 30 per cent in fish as the bacteria gets destroyed in the gut or in the stomach of the fish, said Mr. Shankar.

However, if a biofilm of bacteria is developed, these can not only survive in the stomach, but can also attach itself to the body and slowly release inactive bacteria into the body, thus developing immunity over a long period of time, the research has shown.

Viral infections

“The efficiency of delivery was more than 70 per cent and to 90 per cent during our lab trials,” he said, and added that this could be a simpler, cheaper vaccination method. His Ph.D students have shown how the vaccination helps gut immunity.

Through the recumbent DNA technology (taking the disease causing gene from a virus and inserting this into bacteria), the biofilm vaccination can take on viral infections; while, the system is also being adapted to tackle parasites.

How it started

The idea first took shape when he was pursuing his doctoral studies in microbiology in Canada. “The formation of bacterial bio-films in lungs or in pacemakers and prosthetics was a problem there. These bio-films could not be removed easily, and they kept giving off bacteria,” he said.

“There have been eight international papers (published in journals) by the college in just this one topic. We’re the first to be developing the vaccine,” said Mr. Shankar. With a private company to take up field trials and products, the first indigenous vaccination could soon be available.

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