An Intracellular Mortality-Enhancing Material from Malleomyces Pseudomallei

Abstract

Summary The injection of intracellular material obtained from either a virulent or a relatively avirulent culture of Malleomyces pseudomallei into mice caused marked enhancement of the lethal outcome of concurrent infection with this species. Mortality enhancement was demonstrated employing a number of strains of varying virulence for the mouse but not with 2 avirulent cultures. While enhancement of lethality was similarly demonstrated in infection with Pasteurella pestis, comparably derived material from the latter genus was without significant effect in melioidotic or plague infections. Administration of the intracellular material at 4 to 12 days prior to infection, rather than concurrently with the infecting dose, rendered the mice more resistant to the lethal effects of infection with M. pseudomallei. The active enhancing component was purifed 19-fold and was shown to be a nondialyzable, heat stable, chloroform-resistant, ammonium sulfate-precipitable material free of detectable nucleic acids. Less than 60 μg/mouse of partially purified material elicited an enhanced mortality response. This and higher concentrations were nontoxic.