Fish Immunology (1+1)

Unit 14 - Vaccine

14.7. Oral Vaccination
During the oral vaccination, the vaccine is given orally and it may be either through feed, where it is either mixed along with feed or coated on top of the feed or bio-encapsulated. During oral vaccination proper care must be taken to ensure that the antigen is successfully absorbed into the body. It is because the antigens incorporated in feed may be the heat sensitivity or the digestive system may digest the antigen. So when the vaccine is coated on the feed usually a coating agent is applied to prevent leaching of vaccine or to prevent the digestion of an antigen in the acidic environment of the fish stomach. Bio encapsulations are used usually when the fish fry are to be vaccinated, Bio encapsulation include the live feed such as Artemia nauplii, copepods or rotifers which are fed after incubation in a vaccine suspension. During incubation they accumulate the antigen in their digestive tract and as such, transform themselves into living microcapsules.
Advantages

• Vaccine mixed with feed
• Easiest method for mass vaccination of all sizes of fish
• Saves labour
• Avoids stress to fish

Disadvantages

• Large quantities of vaccines are required
• Some fish may not consume the feed.
• Protection generally weak and of short duration