Jenkins Testopia Plug-in retrieves automated test cases data from Testopia. This data is then set as environment variables. Thus your iterative Build Steps can make use of this information to execute your automated tests.
For instance, you could run ant passing a Test Class as parameter:
/opt/java/apache-ant-1.8.0/bin/ant -DtestClass=$TESTOPIA_TESTCASE_SCRIPT
List of environment variables that Jenkins Testopia Plug-in defines: