Abstract: | A trivalent parainfluenza virus vaccine has been tested in guinea pigs. The parainfluenza 2 virus vaccine component was superior in the magnitude of antibody titers, and in the ability to convert animals serologically after two doses of an undiluted or a 10-fold diluted vaccine. The parainfluenza 1 virus vaccine gave a higher percentage of conversion than parainfluenza 3 virus vaccine after administration of two doses of either undiluted or 10-fold diluted vaccine. |