Discovering key residues of dengue virus NS2b-NS3-protease: New binding sites for antiviral inhibitors design.

The NS2B-NS3 protease is essential for the Dengue Virus (DENV) replication process. This complex constitutes a target for efficient antiviral discovery because a drug could inhibit the viral polyprotein processing. Furthermore, since the protease is highly conserved between the four Dengue virus serotypes, it is probable that a drug would be equally effective against all of them. In this article, a strategy is reported that allowed us to identify influential residues on the function of the Dengue NS2b-NS3 Protease. Moreover, this is a strategy that could be applied to virtually any protein for the search of alternative influential residues, and for non-competitive inhibitor development. First, we incorporated several features derived from computational alanine scanning mutagenesis, sequence, structure conservation, and other structure-based characteristics. Second, these features were used as variables to obtain a multilayer perceptron model to identify defined groups (clusters) of key residues as possible candidate pockets for binding sites of new leads on the DENV protease. The identified residues included: i) amino acids close to the beta sheet-loop-beta sheet known to be important in its closed conformation for NS2b ii) residues close to the active site, iii) several residues evenly spread on the NS2b-NS3 contact surface, and iv) some inner residues most likely related to the overall stability of the protease. In addition, we found concordance on our list of residues with previously identified amino acids part of a highly conserved peptide studied for vaccine development.

Concurrent use of ganciclovir and foscarnet to treat cytomegalovirus infection in AIDS patients.

Ten patients with AIDS and progressive cytomegalovirus disease were treated with ganciclovir and foscarnet concurrently. The patients had received ganciclovir and foscarnet monotherapy a median of 330 days before receiving combination therapy for a median of 80 days. Nine of the 10 patients responded to the combination. No electrolyte abnormalities were noted during combination therapy, but rates of neutropenia (relative rate, combination vs. ganciclovir, 1.99; P = .229) and thrombocytopenia (relative rate, combination vs. ganciclovir, 1.53; P = .616) were higher with combination therapy than with either drug alone. The relative rate of anemia was significantly increased with combination therapy compared with monotherapy (relative rate, combination vs. ganciclovir, 2.69; P = .025). These data suggest that combination ganciclovir and foscarnet therapy after failure of either alone appears to be as effective as standard therapy with single agents. The rate of anemia with combination therapy was significantly greater than either agent alone, but no significant difference was noted among the other parameters of toxicity studied.