Biotechnology and Bioinformatics (1+1)

4.3.1. Introduction

Vaccination is one of the important means of controlling disease. In 1798, Edward Jenner worked on small pox. He employed the term ‘vaccine’ (vaccination for protective inoculation). Pasteur extended Jenner’s findings to other infective diseases such as anthrax, rabies and chicken cholera. By ‘vaccination’ it is possible to induce active immunity to diseases. Immunisation is brought about by the use of killed or weakened(attenuated) bacteria. The immune system recognizes and begins to produce antibodies.

Control of diseases by vaccination has a number of advantages over chemotherapeutic methods.

• Vaccination is preventive measure. The use of vaccines has entered in the field of aquaculture recently. Because of the intensive culture systems, many industries have resorted to the routine use of vaccines which confer a high degree of protection when correctly used.

• Their use in salmon, trout, Mediterranean sea bass and even in shrimp and lobsters is now a standard part of husbandry in all important areas for fish culture in Scandinavia, North and South America and Asia.

• The concept of vaccinating fish on a commercial scale has now been realized with respect to Enteric Red Mouth and Vibriosis.

• Fish immunization began in 1942, with the successful oral immunization of trout against bacterium Aeromonas salmonicida by Duff.

• Fish vaccines in general, fall into three major categories, namely, killed whole cell vaccine, live-attenuated vaccine and recombinant DNA based vaccines.

• Efficacy of these vaccines has been appreciably improved using adjuvants,immuno stimulants or vaccines carriers.

• However, it is still affected by the routes of vaccine administration. In general, injection is better than immersion and oral administration.