Biology subjects

Almeida, D. V.

Publications and source records attributed to Almeida, D. V..

5 recordsLinked to original sources

bioRxiv2026

Contribution of the novel oxazolidinone TBD09 (MK-7762) to regimens with bedaquiline and pretomanid in a mouse model of tuberculosis

Linezolid is a key component of the bedaquiline, pretomanid, linezolid (BPaL) regimen for rifampin-resistant tuberculosis, but dose- and duration-dependent mitochondrial toxicity frequently limits its use. TBD09 (formerly MK-7762) is a novel oxazolidinone developed to maintain antitubercular potency comparable to linezolid while reducing related adverse events. We evaluated the contribution of TBD09 to the bactericidal and sterilizing activities of BPa-based regimens in a murine tuberculosis model. BALB/c mice were aerosol-infected with Mycobacterium tuberculosis H37Rv and treated starting 2 weeks post-infection. In Experiment 1, dose-ranging bactericidal activity of TBD09 (50, 100, 200 mg/kg) was assessed alone and in combination with BPa, with comparison to linezolid and sutezolid. In Experiment 2, the sterilizing activity of TBD09 (200 mg/kg) in combination with BPa and BPa plus moxifloxacin (M) was assessed by evaluating relapse after treatment durations of 4-22 weeks. TBD09 monotherapy was bacteriostatic, similar to linezolid over the first 4 weeks of treatment. The addition of TBD09 to BPa significantly enhanced bactericidal activity comparable to the addition of linezolid. In relapse assessments, BPa+TBD09 resulted in significantly fewer relapses compared to BPa alone after 14 weeks of treatment, and BPaM+TBD09 resulted in significantly fewer relapses compared to BPaM after 10 weeks. Model-based analysis estimated the treatment duration to 95% cure for BPa+TBD09 at 2.7 weeks, compared to 3.2 weeks for BPaL, although the time to 50% cure was similar. These results demonstrate that TBD09 provides bactericidal and sterilizing activity similar to linezolid in combination with BPa(M), supporting further clinical development of TBD09 for tuberculosis.

microbiology↗

bioRxiv2024

Contribution of telacebec to novel drug regimens in a murine tuberculosis model

The clinical efficacy of combination drug regimens containing the first generation diarylquinoline (DARQ) bedaquiline in the treatment of multidrug-resistant tuberculosis has validated ATP synthesis as a vulnerable pathway in Mycobacterium tuberculosis. New DARQs in clinical development may be even more effective than bedaquiline, including against emerging bedaquiline-resistant strains. Telacebec (T) is a novel cytochrome bc1:aa3 oxidase inhibitor that also inhibits ATP synthesis. Based on its demonstrated efficacy as a monotherapy in mice and in a phase 2a clinical trial, we used an established BALB/c mouse model of tuberculosis (TB) to test the contribution of T to novel combination therapies against two strains of M. tuberculosis (H37Rv and HN878) in an effort to find more effective regimens. Overall, T was more effective in regimens against the HN878 strain than against the H37Rv strain, a finding that supports the greater vulnerability of the former strain to T and to genetic depletion of QcrB. Against both strains, combinations of a DARQ, clofazimine (CFZ), and T were highly bactericidal. However, only against HN878 did T contribute synergistically, whereas an antagonistic effect was observed against H37Rv. These results demonstrate the therapeutic potential of T and highlight how differences in the susceptibility of M. tuberculosis strains could lead to different conclusions about a drugs potential contribution to novel drug regimens.

microbiology↗

bioRxiv2023

Contezolid can replace linezolid in a novel combination with bedaquiline and pretomanid in a murine model of tuberculosis

Contezolid is a new oxazolidinone with in vitro and in vivo activity against Mycobacterium tuberculosis comparable to that of linezolid. Pre-clinical and clinical safety studies suggest it may be less toxic than linezolid, making contezolid a potential candidate to replace linezolid in treatment of drug-resistant tuberculosis. We evaluated the dose-ranging activity of contezolid, alone and in combination with bedaquiline and pretomanid, and compared it with linezolid at similar doses, in an established BALB/c mouse model of tuberculosis. Contezolid had an MIC of 1 {micro}g/ml, similar to linezolid, and exhibited similar bactericidal activity in mice. Contezolid-resistant mutants selected in vitro had 10-fold increases in contezolid MIC and harbored mutations in the mce3R gene. These mutants did not display cross-resistance to linezolid. Our results indicate that contezolid has potential to replace linezolid in regimens containing bedaquiline and pretomanid and likely other regimens.

microbiology↗

bioRxiv2021

Growth hormone transgenesis affects thermal tolerance in zebrafish (Danio rerio)

In fish, growth hormone (GH)-transgenesis may modify physiological mechanisms of adaptation when challenged by biotic and abiotic stressors. Thus, we evaluated whether GH overexpression can alter the thermal tolerance of adult and juvenile GH-transgenic zebrafish (Danio rerio). This study compared the thermal tolerance in non-transgenic (NT) and GH-transgenic (T) zebrafish exposed to 13 {degrees}C, 39 {degrees}C, or 28 {degrees}C (control) for 96 h. Mortality rate was checked every 12 h in juvenile (8 week-old) and adult males (6 month-old). Exposure to different temperatures revealed that GH overexpression increases the tolerance of transgenic juveniles exposed to 13 {degrees}C and diminishes the tolerance of juveniles and adults, when exposed to 39 {degrees}C. Additionally, we have analyzed transcriptional expression from the heat shock proteins (HSPs), which are mainly involved in the thermal tolerance mechanism. The mRNA level analysis results revealed that, under controlled conditions (28 {degrees}C), GH-transgenesis upregulates the expression of hsp47, hsp70, hsp90a and heat shock transcription factor (hsf1a) in transgenic juveniles, although the same result was not observed in transgenic adults. Exposure to low temperature did not alter the expression of any analyzed gene, both in adults and in juveniles. Exposure to 39 {degrees}C decreased the expression of all genes analyzed, in GH-transgenic adults. Furthermore, the HSP expression pattern was analyzed via hierarchical clustering. This analysis revealed two major clusters illustrating the dependency of gene changes related to age. These results indicate that the GH overexpression can alter thermal tolerance of fish, depending of age and temperature. Highlights- GH-transgenesis increased the survival rate of juveniles at low temperature; - High temperature is more lethal for juvenile ande adult GH-transgenic zebrafish; - GH-transgenesis increased expression of hsf1a, hsp47, and hsp70 genes in juvenile zebrafish; - hsf1a, hsp47, hsp70, hsp90a, and hsp90b genes expression is diminished in adult zebrafish GH-transgenesis exposure at high temperature. O_FIG O_LINKSMALLFIG WIDTH=142 HEIGHT=200 SRC="FIGDIR/small/445844v1_ufig1.gif" ALT="Figure 1"> View larger version (59K): org.highwire.dtl.DTLVardef@1847289org.highwire.dtl.DTLVardef@7bb056org.highwire.dtl.DTLVardef@75efc9org.highwire.dtl.DTLVardef@d1a9ac_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2019

The evolution of nitroimidazole antibiotic resistance in Mycobacterium tuberculosis

Our inability to predict whether certain mutations will confer antibiotic resistance has made it difficult to rapidly detect the emergence of resistance, identify pre-existing resistant populations and manage our use of antibiotics to effective treat patients and prevent or slow the spread of resistance. Here we investigated the potential for resistance against the new antitubercular nitroimidazole prodrugs pretomanid and delamanid to emerge in Mycobacterium tuberculosis, the causative agent of tuberculosis (TB). Deazaflavin-dependent nitroreductase (Ddn) is the only identified enzyme within M. tuberculosis that activates these prodrugs, via an F420H2-dependent reaction. We show that the native menaquinone-reductase activity of Ddn is important in aerobic respiration and essential for emergence from dormancy, which suggests that for resistance to spread and pose a threat to human health, the native activity of Ddn must be at least partially retained. We tested 75 unique mutations, including all known sequence polymorphisms identified among ~15,000 sequenced M. tuberculosis genomes. Several mutations abolished pretomanid activation in vitro, without causing complete loss of the native activity. We confirmed that a transmissible M. tuberculosis isolate from the hypervirulent Beijing family already possesses one such mutation and is resistant to pretomanid, even though it was never exposed to pretomanid. Notably, delamanid was still effective against this strain, which is consistent with structural analysis that indicates delamanid and pretomanid bind to Ddn differently. We suggest that the mutations identified in this work be monitored for informed use of delamanid and pretomanid treatment and to slow the emergence of resistance.

molecular biology↗