PIC 024-4 and PRO 2000 are naphthalene sulfonate polymers that bind to CD4 with nanomolar affinity and block binding of gp120. Both have activity against human immunodeficiency virus type 1 in H9 cells, peripheral blood mononuclear cells, and primary monocyte/macrophages, are synergistic with zidovudine, and do not inhibit tetanus toxoid-stimulated T-cell proliferation at anti-human immunodeficiency virus type 1 concentrations.

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We describe novel rifamycin derivatives (new chemical entities [NCEs]) that retain significant activity against a comprehensive collection of Staphylococcus aureus strains that are resistant to rifamycins. This collection of resistant strains contains 21 of the 26 known single-amino-acid alterations in RpoB, the target of rifamycins. Some NCEs also demonstrated a lower frequency of resistance development than rifampin and rifalazil in S. aureus as measured in a resistance emergence test. When assayed for activity against the strongest rifamycin-resistant mutants, several NCEs had MICs of 2 g/ml, in contrast to MICs of rifampin and rifalazil, which were 512 g/ml for the same strains. The properties of these NCEs therefore demonstrate a significant improvement over those of earlier rifamycins, which have been limited primarily to combination therapy due to resistance development, and suggest a potential use of these NCEs for monotherapy in several clinical indications.

In response to iron deprivation, Bacillus subtilis secretes a catecholic siderophore, 2,3-dihydroxybenzoyl glycine, which is similar to the precursor of the Escherichia coli siderophore enterobactin. We isolated two sets of B. subtilis DNA sequences that complemented the mutations of several E. coli siderophore-deficient (ent) mutants with defective enterobactin biosynthesis enzymes. One set contained DNA sequences that complemented only an entD mutation. The second set contained DNA sequences that complemented various combinations of entB, entE, entC, and entA mutations. The two sets of DNA sequences did not appear to overlap. AB. subtilis mutant containing an insertion in the region of the entD homolog grew much more poorly in low-iron medium and with markedly different kinetics. These data indicate that (i) at least five of the siderophore biosynthesis genes of B. subtilis can function in E. coli, (ii) the genetic organization of these siderophore genes in B. subtilis is similar to that in E. coli, and (iii) the B. subtilis entD homolog is required for efficient growth in low-iron medium. The nucleotide sequence of the B. subtilis DNA contained in plasmid pENTA22, a clone expressing the B. subtilis entD homolog, revealed the presence of at least two genes. One gene was identified as sfpo, a previously reported gene involved in the production of surfactin in B. subtilis and which is highly homologous to the E. coli entD gene. We present evidence that the E. coli entD and B. subtilis sfpo genes are interchangeable and that their products are members of a new family of proteins which function in the secretion of peptide molecules.

The TonB box, a conserved pentapeptide sequence found in TonB-dependent colicins and receptors, is thought to interact physically with the TonB protein to facilitate TonB-dependent processes. Strains of Escherichia coli were treated in vivo with the synthetic TonB box pentapeptide Glu-Thr-Val-Ile-Val. The pentapeptide inhibited several TonB-dependent processes, including cell growth in low-iron medium, phi 80 infection, and killing by colicins B and Ia. Two unrelated control pentapeptides had no effect on TonB-dependent processes.