Discovery of non-nucleoside inhibitors of HIV-1 reverse transcriptase competing with the nucleotide substrate

How odd! A new class of non-nucleoside reverse transcriptase inhibitors with a 6-vinylpyrimidine scaffold (1) has been found to inhibit HIV-1 reverse transcriptase (RT) by competition with the nucleotide substrate after binding to the non-nucleoside inhibitor binding pocket of the enzyme. Molecular modeling studies have been performed to elucidate their peculiar behavior

Dengue 3 Epidemic, Havana, 2001

In June 2001, dengue transmission was detected in Havana, Cuba; 12,889 cases were reported. Dengue 3, the etiologic agent of the epidemic, caused the dengue hemorrhagic fever only in adults, with 78 cases and 3 deaths. After intensive vector control efforts, no new cases have been detected

Drug Resistance Mutations in the Nucleotide Binding Pocket of Human Immunodeficiency Virus Type 1 Reverse Transcriptase Differentially Affect the Phosphorolysis-Dependent Primer Unblocking Activity in the Presence of Stavudine and Zidovudine and Its Inhibition by Efavirenz

Human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) derivatives with D113E, Y115F, F116Y, Q151E/N, and M184V mutations were studied for their phosphorolysis-mediated resistance to the nucleoside RT inhibitors (NRTIs) zidovudine and stavudine and for their inhibition by the nonnucleoside analogs (NNRTIs) efavirenz and nevirapine. The results presented here indicate that these single amino acid substitutions within the nucleotide binding pocket of the viral RT can independently affect different enzymatic properties, such as catalytic efficiency, drug binding, and phosphorolytic activity. Moreover, small local alterations of the physicochemical properties of the microenvironment around the active site can have profound effects on some NRTIs while hardly affecting other ones. In conclusion, even though different mutations within the nucleotide binding pocket of HIV-1 RT can result in a common phenotype (i.e., drug resistance), the molecular mechanisms underlying this phenotype can be very different. Moreover, the same mutation can give rise to different phenotypes depending on the nature of the substrates and/or inhibitors

SHORT COMMUNICATION - Isolation and Identification of Adenovirus in Hospitalized Children, under Five Years, with Acute Respiratory Disease, in Havana, Cuba

Nine Adenovirus (Ad) strains isolated in Cuba, from 128 nasopharingeal swab specimens of children below five years old, with acute respiratory diseases, during 1996 and 1997, were studied by restriction enzyme analysis of genomic DNA with two endonucleases BamH I and Sma I. All different fragment patterns were compared with the respective prototypes. The identified adenoviruses were Ad 1 (n=4), Ad 2 (n=1) and Ad 6 (n=4). Males were more frequently infected than females. The analysis of the occurrence of these Adenovirus strains of subgenus C revealed that Ad 1 and Ad 6 were the predominant serotypes in 1996 and in 1997, respectively

SHORT COMMUNICATION - Isolation and Identification of Adenovirus in Hospitalized Children, under Five Years, with Acute Respiratory Disease, in Havana, Cuba

Nine Adenovirus (Ad) strains isolated in Cuba, from 128 nasopharingeal swab specimens of children below five years old, with acute respiratory diseases, during 1996 and 1997, were studied by restriction enzyme analysis of genomic DNA with two endonucleases BamH I and Sma I. All different fragment patterns were compared with the respective prototypes. The identified adenoviruses were Ad 1 (n=4), Ad 2 (n=1) and Ad 6 (n=4). Males were more frequently infected than females. The analysis of the occurrence of these Adenovirus strains of subgenus C revealed that Ad 1 and Ad 6 were the predominant serotypes in 1996 and in 1997, respectively

Gln145Met/Leu Changes in Human Immunodeficiency Virus Type 1 Reverse Transcriptase Confer Resistance to Nucleoside and Nonnucleoside Analogs and Impair Virus Replication

The frequencies of multidrug resistance-associated mutations at codons 145, 151, and 69 of the human immunodeficiency virus (HIV) reverse transcriptase (RT) gene in strains from a group of 3,595 highly active antiretroviral therapy (HAART)-experienced patients were 0.22, 2.36, and 0.86%, respectively. Several amino acid substitutions different from the recently reported Gln145Met change (S. Paolucci, F. Baldanti, M. Tinelli, G. Maga, and G. Gerna, AIDS 17:924-927, 2003) were detected at position 145. Thus, amino acid substitutions selected at position 145 were introduced into the wild-type HIV type 1 (HIV-1) RT gene by site-directed mutagenesis, and recombinant HIV strains were assayed for their drug susceptibilities. Only Met and Leu substitutions at position 145 of the HIV-1 RT conferred multidrug resistance, while other amino acid changes did not. Lower levels of replication of the Gln145Met recombinant strain compared with those of both Gln151Met and wild-type recombinant strains were observed. In in vitro inhibition assays, expression and purification of the recombinant Gln145Met HIV-1 RT revealed a strong loss of catalytic efficiency of the mutated enzyme, as well as significant resistance to both zidovudine and efavirenz. Specific amino acid substitutions in the HIV RT nucleotide-binding pocket might affect both antiretroviral drug recognition and binding and decrease the level of virus replication, possibly by interfering with the enzyme activity. This finding may explain the lower frequency of Gln145Met/Leu mutations observed compared with the frequencies of Gln151Met/Leu mutations and the insertion at position 69 in HAART-experienced patients

SHORT COMMUNICATION - Isolation and Identification of Adenovirus in Hospitalized Children, under Five Years, with Acute Respiratory Disease, in Havana, Cuba

Nine Adenovirus (Ad) strains isolated in Cuba, from 128 nasopharingeal swab specimens of children below five years old, with acute respiratory diseases, during 1996 and 1997, were studied by restriction enzyme analysis of genomic DNA with two endonucleases BamH I and Sma I. All different fragment patterns were compared with the respective prototypes. The identified adenoviruses were Ad 1 (n=4), Ad 2 (n=1) and Ad 6 (n=4). Males were more frequently infected than females. The analysis of the occurrence of these Adenovirus strains of subgenus C revealed that Ad 1 and Ad 6 were the predominant serotypes in 1996 and in 1997, respectively

Effects of Drug Resistance Mutations L100I and V106A on the Binding of Pyrrolobenzoxazepinone Nonnucleoside Inhibitors to the Human Immunodeficiency Virus Type 1 Reverse Transcriptase Catalytic Complex

We have previously described a novel class of nonnucleoside reverse transcriptase (RT) inhibitors, the pyrrolobenzoxazepinone (PBO) and the pyridopyrrolooxazepinone (PPO) derivatives, which were effective inhibitors of human immunodeficiency virus type 1 (HIV-1) RT, either wild type or carrying known drug resistance mutations (G. Campiani et al., J. Med. Chem. 42:4462-4470, 1999). The lead compound of the PPO class, (R)-(−)-PPO464, was shown to selectively target the ternary complex formed by the viral RT with its substrates nucleic acid and nucleotide (G. Maga et al., J. Biol. Chem. 276:44653-44662, 2001). In order to better understand the structural basis for this selectivity, we exploited some PBO analogs characterized by various substituents at C-3 and by different inhibition potencies and drug resistance profiles, and we studied their interaction with HIV-1 RT wild type or carrying the drug resistance mutations L100I and V106A. Our kinetic and thermodynamic analyses showed that the formation of the complex between the enzyme and the nucleotide increased the inhibition potency of the compound PBO354 and shifted the free energy (energy of activation, ΔG(#)) for inhibitor binding toward more negative values. The V106A mutation conferred resistance to PBO 354 by increasing its dissociation rate from the enzyme, whereas the L100I mutation mainly decreased the association rate. This latter mutation also caused a severe reduction in the catalytic efficiency of the RT. These results provide a correlation between the efficiency of nucleotide utilization by RT and its resistance to PBO inhibition