scholarly journals Improved Production of Propionic Acid in Propionibacterium jensenii via Combinational Overexpression of Glycerol Dehydrogenase and Malate Dehydrogenase from Klebsiella pneumoniae

2015 ◽  
Vol 81 (7) ◽  
pp. 2256-2264 ◽  
Author(s):  
Long Liu ◽  
Xin Zhuge ◽  
Hyun-dong Shin ◽  
Rachel R. Chen ◽  
Jianghua Li ◽  
...  
Keyword(s):  
Malate Dehydrogenase ◽  
Propionic Acid ◽  
Shuttle Vector ◽  
Fumarate Hydratase ◽  
Glycerol Dehydrogenase ◽  
Potential Candidate ◽  
Wild Type ◽  
Metabolic Intermediate ◽  
Environmental Friendliness ◽  
Content Type

ABSTRACTMicrobial production of propionic acid (PA), an important chemical building block used as a preservative and chemical intermediate, has gained increasing attention for its environmental friendliness over traditional petrochemical processes. In previous studies, we constructed a shuttle vector as a useful tool for engineeringPropionibacterium jensenii, a potential candidate for efficient PA synthesis. In this study, we identified the key metabolites for PA synthesis inP. jenseniiby examining the influence of metabolic intermediate addition on PA synthesis with glycerol as a carbon source under anaerobic conditions. We also further improved PA production via the overexpression of the identified corresponding enzymes, namely, glycerol dehydrogenase (GDH), malate dehydrogenase (MDH), and fumarate hydratase (FUM). Compared to those in wild-typeP. jensenii, the activities of these enzymes in the engineered strains were 2.91- ± 0.17- to 8.12- ± 0.37-fold higher. The transcription levels of the corresponding enzymes in the engineered strains were 2.85- ± 0.19- to 8.07- ± 0.63-fold higher than those in the wild type. The coexpression of GDH and MDH increased the PA titer from 26.95 ± 1.21 g/liter in wild-typeP. jenseniito 39.43 ± 1.90 g/liter in the engineered strains. This study identified the key metabolic nodes limiting PA overproduction inP. jenseniiand further improved PA titers via the coexpression of GDH and MDH, making the engineeredP. jenseniistrain a potential industrial producer of PA.

scholarly journals Development of a Propionibacterium-Escherichia coli Shuttle Vector for Metabolic Engineering of Propionibacterium jensenii, an Efficient Producer of Propionic Acid

2013 ◽  
Vol 79 (15) ◽  
pp. 4595-4602 ◽  
Author(s):  
Xin Zhuge ◽  
Long Liu ◽  
Hyun-dong Shin ◽  
Rachel R. Chen ◽  
Jianghua Li ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Metabolic Engineering ◽  
Propionic Acid ◽  
Shuttle Vector ◽  
Production Capacity ◽  
Glycerol Dehydrogenase ◽  
Sequencing Analysis ◽  
Chloramphenicol Resistance ◽  
Content Type ◽  
Propionibacterium Thoenii

ABSTRACTPropionic acid (PA) is an important chemical building block and is widely applied for organic synthesis, food, feedstuff, and pharmaceuticals. To date, the strains that can efficiently produce PA have includedPropionibacterium thoenii,P. freudenreichii, andP. acidipropionici. In this report, we show thatP. jenseniiATCC 4868 is also able to produce PA in much higher yields than the previously reported strains. To further improve the production capacity, aP. jensenii-Escherichia colishuttle vector was developed for the metabolic engineering ofP. jensenii. Specifically, a 6.9-kb endogenous plasmid, pZGX01, was isolated fromP. acidipropioniciATCC 4875 and sequenced. Since the sequencing analysis indicated that pZGX01 could encode 11 proteins, the transcriptional levels of the corresponding genes were also investigated. Then, aP. jensenii-Escherichia colishuttle vector was constructed using the pZGX01 plasmid, theE. colipUC18 plasmid, and a chloramphenicol resistance gene. Interestingly, not only could the developed shuttle vector be transformed intoP. jenseniiATCC 4868 and 4870, but it also could be transformed intofreudenreichiiATCC 6207 subspecies ofP. freudenreichii. Finally, the glycerol dehydrogenase gene (gldA) fromKlebsiella pneumoniaewas expressed inP. jenseniiATCC 4868 with the constructed shuttle vector. In a 3-liter batch culture, the PA production by the engineeredP. jenseniiATCC 4868 strain reached 28.23 ± 1.0 g/liter, which was 26.07% higher than that produced by the wild-type strain (22.06 ± 1.2 g/liter). This result indicated that the constructed vector can be used a useful tool for metabolic engineering ofP. jensenii.

scholarly journals Oligopeptide Permease A5 Modulates Vertebrate Host-Specific Adaptation of Borrelia burgdorferi

2011 ◽  
Vol 79 (8) ◽  
pp. 3407-3420 ◽  
Author(s):  
B. V. Subba Raju ◽  
Maria D. Esteve-Gassent ◽  
S. L. Rajasekhar Karna ◽  
Christine L. Miller ◽  
Tricia A. Van Laar ◽  
...  
Keyword(s):  
Borrelia Burgdorferi ◽  
Shuttle Vector ◽  
Immunoblot Analysis ◽  
Vertebrate Host ◽  
Transcriptional Analysis ◽  
Wild Type ◽  
Content Type ◽  
Specific Adaptation ◽  
Protein Levels ◽  
Oligopeptide Permease

ABSTRACTBorrelia burgdorferi, the agent of Lyme disease, undergoes rapid adaptive gene expression in response to signals unique to its arthropod vector or vertebrate hosts. Among the upregulated genes under vertebrate host conditions is one of the five annotated homologs of oligopeptide permease A (OppA5, BBA34). A mutant lackingoppA5was constructed in an lp25-deficient isolate ofB. burgdorferistrain B31, and the minimal regions of infectivity were restored via a shuttle vector pBBE22 with or without an intact copy ofbba34. Immunoblot analysis of thebba34mutant revealed a reduction in the levels of RpoS, BosR, and CsrABbwith a concomitant reduction in the levels of OspC, DbpA, BBK32, and BBA64. There were no changes in the levels of OspA, NapA, P66, and three other OppA orthologs. Quantitative transcriptional analysis correlated with the changes in the protein levels. However, thebba34mutant displayed comparable infectivities in the C3H/HeN mice and the wild-type strain, despite the reduction in several pathogenesis-related proteins. Supplementation of the growth medium with increased levels of select components, notably sodium acetate and sodium bicarbonate, restored the levels of several proteins in thebba34mutant to wild-type levels. We speculate that the transport of acetate appears to contribute to the accumulation of key metabolites, like acetyl phosphate, that facilitate the adaptation ofB. burgdorferito the vertebrate host by the activation of the Rrp2-RpoN-RpoS pathway. These studies underscore the importance of solute transport to host-specific adaptation ofB. burgdorferi.

scholarly journals Assessment of the Plasmodium falciparum Preerythrocytic Antigen UIS3 as a Potential Candidate for a Malaria Vaccine

2016 ◽  
Vol 85 (3) ◽  
Author(s):  
Rhea J. Longley ◽  
Benedict R. Halbroth ◽  
Ahmed M. Salman ◽  
Katie J. Ewer ◽  
Susanne H. Hodgson ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Viral Vectors ◽  
Vaccine Candidate ◽  
Mouse Strains ◽  
Potential Candidate ◽  
Wild Type ◽  
Content Type ◽  
Malaria Vaccines ◽  
Modified Vaccinia Virus Ankara ◽  
Controlled Human Malaria Infection

ABSTRACT Efforts are under way to improve the efficacy of subunit malaria vaccines through assessments of new adjuvants, vaccination platforms, and antigens. In this study, we further assessed the Plasmodium falciparum antigen upregulated in infective sporozoites 3 (PfUIS3) as a vaccine candidate. PfUIS3 was expressed in the viral vectors chimpanzee adenovirus 63 (ChAd63) and modified vaccinia virus Ankara (MVA) and used to immunize mice in a prime-boost regimen. We previously demonstrated that this regimen could provide partial protection against challenge with chimeric P. berghei parasites expressing PfUIS3. We now show that ChAd63-MVA PfUIS3 can also provide partial cross-species protection against challenge with wild-type P. berghei parasites. We also show that PfUIS3-specific cellular memory responses could be recalled in human volunteers exposed to P. falciparum parasites in a controlled human malaria infection study. When ChAd63-MVA PfUIS3 was coadministered with the vaccine candidate P. falciparum thrombospondin-related adhesion protein (PfTRAP) expressed in the ChAd63-MVA system, there was no significant change in immunogenicity to either vaccine. However, when mice were challenged with double chimeric P. berghei-P. falciparum parasites expressing both PfUIS3 and PfTRAP, vaccine efficacy was improved to 100% sterile protection. This synergistic effect was evident only when the two vaccines were mixed and administered at the same site. We have therefore demonstrated that vaccination with PfUIS3 can induce a consistent delay in patent parasitemia across mouse strains and against chimeric parasites expressing PfUIS3 as well as wild-type P. berghei; when this vaccine is combined with another partially protective regimen (ChAd63-MVA PfTRAP), complete protection is induced.

scholarly journals A Replicative Plasmid Vector Allows Efficient Complementation of Pathogenic Leptospira Strains

2015 ◽  
Vol 81 (9) ◽  
pp. 3176-3181 ◽  
Author(s):  
Christopher J. Pappas ◽  
Nadia Benaroudj ◽  
Mathieu Picardeau
Keyword(s):  
Genetic Manipulation ◽  
Shuttle Vector ◽  
Plasmid Vector ◽  
Wild Type ◽  
Pathogenic Leptospira ◽  
Content Type ◽  
Large Panel ◽  
Stable Plasmid ◽  
The Stability ◽  
Functional Copy

ABSTRACTLeptospirosis, an emerging zoonotic disease, remains poorly understood because of a lack of genetic manipulation tools available for pathogenic leptospires. Current genetic manipulation techniques include insertion of DNA by random transposon mutagenesis and homologous recombination via suicide vectors. This study describes the construction of a shuttle vector, pMaORI, that replicates within saprophytic, intermediate, and pathogenic leptospires. The shuttle vector was constructed by the insertion of a 2.9-kb DNA segment including theparA,parB, andrepgenes into pMAT, a plasmid that cannot replicate inLeptospiraspp. and contains a backbone consisting of anaadAcassette,oriR6K, andoriTRK2/RP4. The inserted DNA segment was isolated from a 52-kb region withinLeptospiramayottensisstrain 200901116 that is not found in the closely related strainL. mayottensis200901122. Because of the size of this region and the presence of bacteriophage-like proteins, it is possible that this region is a result of a phage-related genomic island. The stability of the pMaORI plasmid within pathogenic strains was tested by passaging cultures 10 times without selection and confirming the presence of pMaORI. Concordantly, we report the use oftranscomplementation in the pathogenLeptospira interrogans. Transformation of a pMaORI vector carrying a functional copy of theperRgene in a null mutant background restores the expression of PerR and susceptibility to hydrogen peroxide comparable to that of wild-type cells. In conclusion, we demonstrate the replication of a stable plasmid vector in a large panel ofLeptospirastrains, including pathogens. The shuttle vector described will expand our ability to perform genetic manipulation ofLeptospiraspp.

scholarly journals Clostridium beijerinckii andClostridium difficile Detoxify Methylglyoxal by a Novel Mechanism Involving Glycerol Dehydrogenase

2001 ◽  
Vol 67 (5) ◽  
pp. 2004-2010 ◽  
Author(s):  
Hemachandra Liyanage ◽  
Shelby Kashket ◽  
Michael Young ◽  
Eva R. Kashket
Keyword(s):  
Single Copy ◽  
Clostridium Beijerinckii ◽  
Glycerol Dehydrogenase ◽  
Insertion Mutant ◽  
Wild Type ◽  
Metabolic Intermediate ◽  
Gram Positive Bacteria ◽  
Cell Extracts ◽  
Essential Function ◽  
Production Cell

ABSTRACT In contrast to gram-negative bacteria, little is known about the mechanisms by which gram-positive bacteria degrade the toxic metabolic intermediate methylglyoxal (MG). Clostridium beijerinckiiBR54, a Tn1545 insertion mutant of the NCIMB 8052 strain, formed cultures that contained significantly more (free) MG than wild-type cultures. Moreover, BR54 was more sensitive to growth inhibition by added MG than the wild type, suggesting that it has a reduced ability to degrade MG. The single copy of Tn1545 in this strain lies just downstream from gldA, encoding glycerol dehydrogenase. As a result of antisense RNA production, cell extracts of BR54 possess significantly less glycerol dehydrogenase activity than wild-type cell extracts (H. Liyanage, M. Young, and E. R. Kashket, J. Mol. Microbiol. Biotechnol. 2:87–93, 2000). Inactivation of gldA in both C. beijerinckiiand Clostridium difficile gave rise to pinpoint colonies that could not be subcultured, indicating that glycerol dehydrogenase performs an essential function in both organisms. We propose that this role is detoxification of MG. To our knowledge, this is the first report of targeted gene disruption in the C. difficilechromosome.

scholarly journals Mutations in fbiD (Rv2983) as a Novel Determinant of Resistance to Pretomanid and Delamanid in Mycobacterium tuberculosis

2020 ◽  
Vol 65 (1) ◽  
pp. e01948-20
Author(s):  
Dalin Rifat ◽  
Si-Yang Li ◽  
Thomas Ioerger ◽  
Keshav Shah ◽  
Jean-Philippe Lanoix ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Clinical Evidence ◽  
Clinical Samples ◽  
Loss Of Function ◽  
Wild Type ◽  
Content Type ◽  
Solid Media ◽  
High Level ◽  
Level Resistance

ABSTRACTThe nitroimidazole prodrugs delamanid and pretomanid comprise one of only two new antimicrobial classes approved to treat tuberculosis (TB) in 50 years. Prior in vitro studies suggest a relatively low barrier to nitroimidazole resistance in Mycobacterium tuberculosis, but clinical evidence is limited to date. We selected pretomanid-resistant M. tuberculosis mutants in two mouse models of TB using a range of pretomanid doses. The frequency of spontaneous resistance was approximately 10−5 CFU. Whole-genome sequencing of 161 resistant isolates from 47 mice revealed 99 unique mutations, of which 91% occurred in 1 of 5 genes previously associated with nitroimidazole activation and resistance, namely, fbiC (56%), fbiA (15%), ddn (12%), fgd (4%), and fbiB (4%). Nearly all mutations were unique to a single mouse and not previously identified. The remaining 9% of resistant mutants harbored mutations in Rv2983 (fbiD), a gene not previously associated with nitroimidazole resistance but recently shown to be a guanylyltransferase necessary for cofactor F420 synthesis. Most mutants exhibited high-level resistance to pretomanid and delamanid, although Rv2983 and fbiB mutants exhibited high-level pretomanid resistance but relatively small changes in delamanid susceptibility. Complementing an Rv2983 mutant with wild-type Rv2983 restored susceptibility to pretomanid and delamanid. By quantifying intracellular F420 and its precursor Fo in overexpressing and loss-of-function mutants, we provide further evidence that Rv2983 is necessary for F420 biosynthesis. Finally, Rv2983 mutants and other F420H2-deficient mutants displayed hypersusceptibility to some antibiotics and to concentrations of malachite green found in solid media used to isolate and propagate mycobacteria from clinical samples.

scholarly journals The Serratia marcescens Siderophore Serratiochelin Is Necessary for Full Virulence during Bloodstream Infection

2020 ◽  
Vol 88 (8) ◽  
Author(s):  
Danelle R. Weakland ◽  
Sara N. Smith ◽  
Bailey Bell ◽  
Ashootosh Tripathi ◽  
Harry L. T. Mobley
Keyword(s):  
Serratia Marcescens ◽  
Bloodstream Infection ◽  
Iron Acquisition ◽  
Gene Clusters ◽  
Clinical Isolates ◽  
Wild Type ◽  
Serratia Plymuthica ◽  
Content Type ◽  
Cas Assay ◽  
Essential Nutrient

ABSTRACT Serratia marcescens is a bacterium frequently found in the environment, but over the last several decades it has evolved into a concerning clinical pathogen, causing fatal bacteremia. To establish such infections, pathogens require specific nutrients; one very limited but essential nutrient is iron. We sought to characterize the iron acquisition systems in S. marcescens isolate UMH9, which was recovered from a clinical bloodstream infection. Using RNA sequencing (RNA-seq), we identified two predicted siderophore gene clusters (cbs and sch) that were regulated by iron. Mutants were constructed to delete each iron acquisition locus individually and in conjunction, generating both single and double mutants for the putative siderophore systems. Mutants lacking the sch gene cluster lost their iron-chelating ability as quantified by the chrome azurol S (CAS) assay, whereas the cbs mutant retained wild-type activity. Mass spectrometry-based analysis identified the chelating siderophore to be serratiochelin, a siderophore previously identified in Serratia plymuthica. Serratiochelin-producing mutants also displayed a decreased growth rate under iron-limited conditions created by dipyridyl added to LB medium. Additionally, mutants lacking serratiochelin were significantly outcompeted during cochallenge with wild-type UMH9 in the kidneys and spleen after inoculation via the tail vein in a bacteremia mouse model. This result was further confirmed by an independent challenge, suggesting that serratiochelin is required for full S. marcescens pathogenesis in the bloodstream. Nine other clinical isolates have at least 90% protein identity to the UMH9 serratiochelin system; therefore, our results are broadly applicable to emerging clinical isolates of S. marcescens causing bacteremia.

scholarly journals MetR-Regulated Vibrio cholerae Metabolism Is Required for Virulence

mBio ◽  
2012 ◽  
Vol 3 (5) ◽  
Author(s):  
Ryan W. Bogard ◽  
Bryan W. Davies ◽  
John J. Mekalanos
Keyword(s):  
Amino Acid ◽  
Vibrio Cholerae ◽  
Virulence Factor ◽  
Current Knowledge ◽  
Intestinal Colonization ◽  
Wild Type ◽  
Pathogenic Potential ◽  
Content Type ◽  
Mouse Intestine

ABSTRACTLysR-type transcriptional regulators (LTTRs) are the largest, most diverse family of prokaryotic transcription factors, with regulatory roles spanning metabolism, cell growth and division, and pathogenesis. Using a sequence-defined transposon mutant library, we screened a panel ofV. choleraeEl Tor mutants to identify LTTRs required for host intestinal colonization. Surprisingly, out of 38 LTTRs, only one severely affected intestinal colonization in the suckling mouse model of cholera: the methionine metabolism regulator, MetR. Genetic analysis of genes influenced by MetR revealed thatglyA1andmetJwere also required for intestinal colonization. Chromatin immunoprecipitation of MetR and quantitative reverse transcription-PCR (qRT-PCR) confirmed interaction with and regulation ofglyA1, indicating that misregulation ofglyA1is likely responsible for the colonization defect observed in themetRmutant. TheglyA1mutant was auxotrophic for glycine but exhibited wild-type trimethoprim sensitivity, making folate deficiency an unlikely cause of its colonization defect. MetJ regulatory mutants are not auxotrophic but are likely altered in the regulation of amino acid-biosynthetic pathways, including those for methionine, glycine, and serine, and this misregulation likely explains its colonization defect. However, mutants defective in methionine, serine, and cysteine biosynthesis exhibited wild-type virulence, suggesting that these amino acids can be scavenged in vivo. Taken together, our results suggest that glycine biosynthesis may be required to alleviate an in vivo nutritional restriction in the mouse intestine; however, additional roles for glycine may exist. Irrespective of the precise nature of this requirement, this study illustrates the importance of pathogen metabolism, and the regulation thereof, as a virulence factor.IMPORTANCEVibrio choleraecontinues to be a severe cause of morbidity and mortality in developing countries. Identification ofV. choleraefactors critical to disease progression offers the potential to develop or improve upon therapeutics and prevention strategies. To increase the efficiency of virulence factor discovery, we employed a regulator-centric approach to multiplex our in vivo screening capabilities and allow whole regulons inV. choleraeto be interrogated for pathogenic potential. We identified MetR as a new virulence regulator and serine hydroxymethyltransferase GlyA1 as a new MetR-regulated virulence factor, both required byV. choleraeto colonize the infant mouse intestine. Bacterial metabolism is a prerequisite to virulence, and current knowledge of in vivo metabolism of pathogens is limited. Here, we expand the known role of amino acid metabolism and regulation in virulence and offer new insights into the in vivo metabolic requirements ofV. choleraewithin the mouse intestine.

scholarly journals Large-Scale Synonymous Substitutions in Cucumber Mosaic Virus RNA 3 Facilitate Amino Acid Mutations in the Coat Protein

2018 ◽  
Vol 92 (22) ◽  
Author(s):  
Tomofumi Mochizuki ◽  
Rie Ohara ◽  
Marilyn J. Roossinck
Keyword(s):  
Amino Acid ◽  
Secondary Structure ◽  
Viral Genome ◽  
Large Scale ◽  
Viral Rna ◽  
Wild Type ◽  
Competitive Fitness ◽  
Content Type ◽  
Synonymous Substitutions ◽  
Cp Gene

ABSTRACTThe effect of large-scale synonymous substitutions in a small icosahedral, single-stranded RNA viral genome on virulence, viral titer, and protein evolution were analyzed. The coat protein (CP) gene of the Fny stain of cucumber mosaic virus (CMV) was modified. We created four CP mutants in which all the codons of nine amino acids in the 5′ or 3′ half of the CP gene were replaced by either the most frequently or the least frequently used synonymous codons in monocot plants. When the dicot host (Nicotiana benthamiana) was inoculated with these four CP mutants, viral RNA titers in uninoculated symptomatic leaves decreased, while all mutants eventually showed mosaic symptoms similar to those for the wild type. The codon adaptation index of these four CP mutants against dicot genes was similar to those of the wild-type CP gene, indicating that the reduction of viral RNA titer was due to deleterious changes of the secondary structure of RNAs 3 and 4. When two 5′ mutants were serially passaged inN. benthamiana, viral RNA titers were rapidly restored but competitive fitness remained decreased. Although no nucleic acid changes were observed in the passaged wild-type CMV, one to three amino acid changes were observed in the synonymously mutated CP of each passaged virus, which were involved in recovery of viral RNA titer of 5′ mutants. Thus, we demonstrated that deleterious effects of the large-scale synonymous substitutions in the RNA viral genome facilitated the rapid amino acid mutation(s) in the CP to restore the viral RNA titer.IMPORTANCERecently, it has been known that synonymous substitutions in RNA virus genes affect viral pathogenicity and competitive fitness by alteration of global or local RNA secondary structure of the viral genome. We confirmed that large-scale synonymous substitutions in the CP gene of CMV resulted in decreased viral RNA titer. Importantly, when viral evolution was stimulated by serial-passage inoculation, viral RNA titer was rapidly restored, concurrent with a few amino acid changes in the CP. This novel finding indicates that the deleterious effects of large-scale nucleic acid mutations on viral RNA secondary structure are readily tolerated by structural changes in the CP, demonstrating a novel part of the adaptive evolution of an RNA viral genome. In addition, our experimental system for serial inoculation of large-scale synonymous mutants could uncover a role for new amino acid residues in the viral protein that have not been observed in the wild-type virus strains.

Thymidine kinase-mediated killing of rat brain tumors

1993 ◽  
Vol 79 (5) ◽  
pp. 729-735 ◽  
Author(s):  
David Barba ◽  
Joseph Hardin ◽  
Jasodhara Ray ◽  
Fred H. Gage
Keyword(s):  
Gene Therapy ◽  
Brain Tumors ◽  
Tumor Cells ◽  
Wild Type ◽  
Cns Disorders ◽  
Content Type ◽  
Potential Applications ◽  
Ganciclovir Treatment ◽  
The Brain ◽  
Fine Print

✓ Gene therapy has many potential applications in central nervous system (CNS) disorders, including the selective killing of tumor cells in the brain. A rat brain tumor model was used to test the herpes simplex virus (HSV)-thymidine kinase (TK) gene for its ability to selectively kill C6 and 9L tumor cells in the brain following systemic administration of the nucleoside analog ganciclovir. The HSV-TK gene was introduced in vitro into tumor cells (C6-TK and 9L-TK), then these modified tumor cells were evaluated for their sensitivity to cell killing by ganciclovir. In a dose-response assay, both C6-TK and 9L-TK cells were 100 times more sensitive to killing by ganciclovir (median lethal dose: C6-TK, 0.1 µg ganciclovir/ml; C6, 5.0 µg ganciclovir/ml) than unmodified wild-type tumor cells or cultured fibroblasts. In vivo studies confirmed the ability of intraperitoneal ganciclovir administration to kill established brain tumors in rats as quantified by both stereological assessment of brain tumor volumes and studies of animal survival over 90 days. Rats with brain tumors established by intracerebral injection of wild-type or HSV-TK modified tumor cells or by a combination of wild-type and HSV-TK-modified cells were studied with and without ganciclovir treatments. Stereological methods determined that ganciclovir treatment eliminated tumors composed of HSV-TK-modified cells while control tumors grew as expected (p < 0.001). In survival studies, all 10 rats with 9L-TK tumors treated with ganciclovir survived 90 days while all untreated rats died within 25 days. Curiously, tumors composed of combinations of 9L and 9L-TK cells could be eliminated by ganciclovir treatments even when only one-half of the tumor cells carried the HSV-TK gene. While not completely understood, this additional tumor cell killing appears to be both tumor selective and local in nature. It is concluded that HSV-TK gene therapy with ganciclovir treatment does selectively kill tumor cells in the brain and has many potential applications in CNS disorders, including the treatment of cancer.

Sign in / Sign up

Export Citation Format

Share Document