Fish Immunology (1+1)

Unit 14 - Vaccine

Types of vaccine
14.2. Killed whole cell vaccines
Killed whole cell vaccine is a suspension of heat or chemical-killed pathogens that are able to induce specific protective immune response against those pathogens when administered into the host. Killed whole cell vaccine are administrated when it is unsafe to use live microorganisms. These vaccines are prepared from normal wild type bacteria that are made nonpathogenic usually by treating with heat, formaldehyde or gamma irradiation.
Killed whole cell vaccine can be used in controlling some of the important fish bacterial pathogens like V. anguiliarum, V. salmonicida, V. ordalli, Y. ruckeri, E. tarda and A. sarmonicida.
Among carp virus killed vaccine of spring viremia of carp virus (SVCV) was commercially available for some years.
Advantages:

• Safe to use
• Cheaper than live attenuated vaccine
• Storage is easier than live vaccine

Disadvantages:

• Large number of microorganisms is required to stimulate immunity.
• High cost of their production in cell culture,
• Difficulty in the purification and delivery.
• In general killed vaccines alone trigger only the humoral immune response
• Needs to be given booster doses
• Presence of some un-inactivated microbes can lead to vaccine-associated disease.
• Inactivation, by formaldehyde may alter antigenicity.