Metabolic Characterization of the Genus Brucella VI. Growth Stimulation by i -Erythritol Compared with Strain Virulence for Guinea Pigs

Abstract

Strains of Brucella abortus isolated 20 to 38 years ago and strains recently isolated were assessed for their virulence to guinea pigs and for their ability to grow in halfstrength Tryptose Broth with and without i-erythritol. The recently isolated strains were virulent and i-erythritol enhanced their growth. The aged strains were avirulent and grew equally well in both media. Three of the recently isolated strains were subcultured serially every 24 hr alternately on Tryptose Agar slants and in halfstrength Tryptose Broth without i-erythritol. After 8 to 13 such transfers, the growth of each strain was equivalent in both media. The subculture on which growth equivalence occurred was retested for virulence. None of the three strains had decreased in its virulence for guinea pigs. The conclusion was drawn that strain virulence for guinea pigs and growth enhancement by i-erythritol are independent characteristics. Williams et al. (9) observed that the addition of i-erythritol to half-strength tryptic digest broth

Adaptation of the brucellae to their intracellular niche

“…Experimental evidence strongly suggests that the differential virulence of the B. abortus dhbC mutant in mice and ruminants stems from the inability of this mutant to replicate efficiently in the presence of the four-carbon sugar alcohol erythritol when faced with iron limitation (Bellaire et al, 2003b). Erythritol is the favoured carbon source for B. abortus strains (Meyer, 1967;Sperry and Robertson, 1975), and ruminant placental trophoblasts begin producing copious quantities of this compound at the onset of the last trimester of pregnancy (Smith et al, 1961;Enright, 1990). This is the same time at which pregnant ruminants are most susceptible to infection by the brucellae.…”

DNA sequence and expression of the 36-kilodalton outer membrane protein gene of Brucella abortus

“…At that time these investigators suggested that the increased virulence of in vivo-grown organisms in a guinea pig model was due to a cell wall component distinct from the major antigenic lipopolysaccharide. In addition, B. abortus has been shown to preferentially utilize the four-carbon aliphatic alcohol erythritol, which is present at high concentrations in infected bovine tissues (19). Our goal was to determine any changes which potentially occur in B. abortus as a result of changing environmental conditions during the course of infection and which play a role in intracellular survival and virulence.…”

Erythritol catabolism by Brucella abortus

“…In contrast to domestic animals, the bacteria cause a chronic disease in man in which cells of the reticuloendothelial system are parasitized. It is significant that erythritol is present only in fetal fluids and tissues of animals which suffer acute infectious abortions; however, considerable controversy has been raised concerning possible relationship(s) between erythritol utilization and virulence (23,24). Infections with B. melitensis and B. suis have been enhanced by co-injection of erythritol (20).…”

“…McCullough and Beal (22) studied the utilization of carbohydrates by 12 strains of Brucella and found that erythritol was the only sugar which supported growth of all strains. More recently, several hundred strains of Brucella were examined for ability to catabolize erythritol, and only the culture of B. abortus used for vaccine production in the United States was negative (18,23,24).Since animal tissues do not appear to catab-619 on August 1, 2020 by guest…”