VMC 221: Veterinary Immunology and Serology (1+1)

POTENCY

• It is required for each lot prior to release and designed to correlate with host animal vaccination - challenge efficacy studies. For killed viral (or) bacterial products, potency test should be conducted in lab animals (or) by quantitative in vitro methods. The potency of live vaccine is generally measured by means of bacterial count (or) by virus titration.
• The bacterial count of the live bacterial vaccine must be sufficiently greater than that shown to be protective in immunogenicity test.
• As a rule the virus titre of the live viral vaccine must be sufficiently greater than that shown to be protective in immunogenicity test.
• For bacterial vaccine the bacterial count should be twice as that is shown in immunogenicity test. Whereas for viral vaccine it is 5 times.
• Usually the potency test is conducted in guinea pig by intradermal injection.
• After 14 days of immunization the guinea pigs to be challenged  with virulent strain of microorganisms.
• Keep appropriate control.
• Vaccinated and control guinea pigs to be observed for  daily for 20 days after challenging .
• The vaccinted guinea pig should not show any clinical signs and lesion on post mortem examination.