Examination of the bactericidal and opsonic activity of normal human serum for a mucoid and nonmucoid strain ofPseudomonas aeruginosa

The bactericidal and opsonic activity of fresh human serum (FHS) for a mucoid strain ofPseudomonas aeruginosa, 144M, and its spontaneous nonmucoid revertant, 144NM, was examined. Strain 144M was sensitive to the bactericidal activity of FHS, but strain 144NM was not. This bactericidal activity was due to the combined interaction of IgG and IgM with complement, activated through both pathways. Neither 144M nor 144NM was ingested by human polymorphonuclear leukocytes (PMNL) without FHS. Whereas maximal phagocytosis of 144M required only 5% FHS, comparable ingestion of 144NM required 25% FHS. Maximal phagocytosis of either 144M or 144NM required IgG, IgM, and complement. However, 144M required a heat-sensitive opsonic IgG, whereas 144NM required a heat-resistant IgG. Using selective absorption techniques, the targets for bactericidal and opsonic immunoglobulins on 144M and 144NM appeared to be different, suggesting that the variant 144NM had one or more altered, absent, or inaccessible cell surface components that account for differences in response to FHS and PMNL.     

A Novel Imidazole Nucleoside Containing a Diaminodihydro-S-triazine as a Substituent: Inhibitory Activity Against the West Nile Virus NTPase/Helicase

The attempted synthesis of a ring-expanded guanosine (1) containing the imidazo[4,5-e][1,3]diazepine ring system by condensation of 1-(2′-deoxy-β-D-erythropentofuranosyl)-4-ethoxycarbonylimidazole-5-carbaldehyde (2) with guanidine resulted in the formation of an unexpected product, 1-(2′-deoxy-β-D-erythropentofuranosyl)-5-(2,4-diamino-3,6-dihydro-1,3,5-triazin-6-yl)imidazole-4-carboxamide (7). The structure as well as the pathway of formation of 7 was corroborated by isolation of the intermediate, followed by its conversion to the product. Nucleoside 7 showed promising in vitro anti-helicase activity against the West Nile virus NTPase/ helicase with an IC ₅₀ of 3-10 μg/mL.