By intraspinous injections of specimens of poliomyelitic virus of suitable virulence infection can be caused regularly in Macacus rhesus monkeys. The virus passes from the subarachnoid spaces into the nervous tissues in which it multiplies, and into the blood. The constant involvement of the pia-arachnoid membranes in poliomyelitis, even when no paralysis occurs, and the fact that infection can...

Salmonella enteritidis is highly virulent for the mouse causing an infection resembling mouse typhoid. Survivors of the infection are completely resistant to reinfection and eliminate a large challenge dose of virulent organisms within 72 hr. The antigenically related Salmonella gallinarum was almost avirulent for the mouse but animals vaccinated with this organism were equally capable of elimi...

Experimental viral disease studies in volunteers have clarified many aspects of the pathogenesis of human viral disease. Recently, interest has focused on rhinovirus-associated asthma exacerbations, and new volunteer studies have suggested that airway responsiveness (AR) is enhanced during a cold. For scientific, ethical and safety reasons, it is important to use validated methods for the prepa...