An alternative method for evaluating potency of modified live canine parainfluenza virus vaccine

Two evaluation procedures for efficacy testing of modified canine parainfluenza virus master seed within the restrictions of the seed-lot principle test are described. It is concluded the evaluation by post-mortem examination for specific hemorrhagic lung lesions more nearly reflects the objective of the seed-lot principle test method than does reduced days of shedding virulent virus after challenge. The problems associated with the seed-lot principle test method when working with diseases which are difficult to reproduce or modified viruses which show a dose response are discussed.