Prevention of canine distemper with measles vaccine.

This research aimed to investigate the practicability of using measles vaccine to prevent canine distemper.Eight local-bred littermate puppies were tested.Three dogs(group A)were inoculated twice with live-attenuated measles vaccine at a dose of 2~2.5 individual doses per dog.The dog sera collected before inoculation and at day 7 post-inoculation were subjected to micro-plate neutralization tests to determine titers of canine distemper virus(CDV)neutralizing antibody.Peripheral circulating whole blood samples from the immunized dogs were transferred to the unvaccinated dogs(group B,n=3)at a dose of 3.2~3.5mL each,and 3 days later,both groups as well as group C(n=2)as control were challenged with Vero cell-isolated/cultured Kunming strain of CDV via muscular injection or intranasal administration at a dose of 2 000 TCID 50(about 5 600 PFU)each.As a result,all the puppies,whether immunized with attenuated measles vaccine or not,had undetectable CDV neutralizing antibody(titers lower than 1∶ 4);both group A and group B didn't develop clinical symptoms of canine distemper during 14 days post-challenge,while group C contracted an apparent but not lethal infection.The results obtained above show that live-attenuated measles vaccine can not induce CDV neutralizing antibody but can provide dogs potent cellular immunity to CDV infection.