Studies on the immunology of murine leprosy effects of vaccinations and previous infection

ABSTRACT

1- Injection of a saline vaccine of heat-killed murine leprosy bacilli some time prior to inoculation of live bacilli, causes inhibition of onset (prophylaxis) in a relatively high degree, although not totally. When the vaccine is given simulataneously with inoculation of live bacilli, there is a distinct but lesser degree of inhibition of onset. 2- Injection of a vaccine prepared by adding liquid paraffin to killed murine leprosy bacilli did not completely prevent infection by a challenge inoculation of live bacilli, but onset was strongly inhibited. The effect of this vaccine was stronger than that of the saline vaccine. 3- Administration of a liquid-paraffin vaccine of nonpathogenic acid-fast bacilli in place of murine leprosy bacilli resulted in a slight degree of immunity. 4- When secondary infection was attempted in rats already infected with murine leprosy, resistance greater than that induced by injectionnof the liquid paraffin vaccine was observed. When the challenge inoculum was a 0.5 cc. dose of a 10-4 leproma suspension, complete prevention was observed. 5- An acute reaction of the skin over the site of the reinoculation dose, resembling the Koch phenomenon in tuberculosis, was not observed. The size of the primary lesion did not influence the progress of the primary lesion. It is indicated that a certain degree of immunity can be attained by injection of killed or live murine leprosy bacilli in rats, and that it is also possible to obtain such an effect nonspecifically but in lesser degrees by injection of vaccines of other acid-fast bacilli.