bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanism and Suppression of Lysostaphin Resistance in Oxacillin-ResistantStaphylococcus aureus
Authors: Climo Michael W. , Ehlert Kerstin , Archer Gordon L. 
Published: July 2002

ABSTRACTThe potential for the development of resistance in oxacillin-resistantStaphylococcus aureus(ORSA) to lysostaphin, a glycylglycine endopeptidase produced byStaphylococcus simulansbiovarstaphylolyticus, was examined in vitro and in an in vivo model of infection. Following in vitro exposure of ORSA to subinhibitory concentrations of lysostaphin, lysostaphin-resistant mutants were idenitifed among all isolates examined. Resistance to lysostaphin was associated with a loss of resistance to β-lactams and a change in the muropeptide interpeptide cross bridge from pentaglycine to a single glycine. Mutations infemA, the gene required for incorporation of the second and third glycines into the cross bridge, were found following PCR amplification and nucleotide sequence analysis. Complementation of lysostaphin-resistant mutants with pBBB31, which encodesfemA, restored the phenotype of oxacillin resistance and lysostaphin susceptibility. Addition of β-lactam antibiotics to lysostaphin in vitro prevented the development of lysostaphin-resistant mutants. In the rabbit model of experimental endocarditis, administration of a low dose of lysostaphin for 3 days led predictably to the appearance of lysostaphin-resistant ORSA mutants in vegetations. Coadministration of nafcillin with lysostaphin prevented the emergence of lysostaphin-resistant mutants and led to a mean reduction in aortic valve vegetation counts of 7.5 log10CFU/g compared to those for untreated controls and eliminated the isolation of lysostaphin-resistant mutants from aortic valve vegetations. Treatment with nafcillin and lysostaphin given alone led to mean reductions of 1.35 and 1.65 log10CFU/g respectively. In ORSA, resistance to lysostaphin was associated with mutations infemA, but resistance could be suppressed by the coadministration of β-lactam antibiotics.
GT160-246, a Toxin Binding Polymer for Treatment of
Clostridium difficile
Colitis
Authors: Kurtz Caroline B. , Cannon E. Pat , Brezzani Alex , Pitruzzello Mary , Dinardo Carol , Rinard Emilie , Acheson David W. K. , Fitzpatrick Richard , Kelly Pamela , Shackett Keith , Papoulis Andrew T. , Goddard Philip J. , Barker Robert H. , Palace Gerard P. , Klinger Jeffrey D. 
Published: July 2002

ABSTRACT

GT160-246, a high-molecular-weight soluble anionic polymer, was tested in vitro and in vivo for neutralization of
Clostridium difficile
toxin A and B activities. Five milligrams of GT160-246 per ml neutralized toxin-mediated inhibition of protein synthesis in Vero cells induced by 5 ng of toxin A per ml or 1.25 ng of toxin B per ml. In ligated rat ileal loops, 1 mg of GT160-246 neutralized fluid accumulation caused by 5 μg of toxin A. At doses as high as 80 mg/loop, cholestyramine provided incomplete neutralization of fluid accumulation caused by 5 μg of toxin A. GT160-246 protected 80% of the hamsters from mortality caused by infection with
C. difficile
, whereas cholestyramine protected only 10% of animals. Treatment of
C. difficile
-infected hamsters with metronidazole initially protected 100% of the hamsters from mortality, but upon removal of treatment, 80% of the hamsters had relapses and died. In contrast, removal of GT160-246 treatment did not result in disease relapse in the hamsters. GT160-246 showed no antimicrobial activity in tests with a panel of 16 aerobic bacteria and yeast and 22 anaerobic bacteria and did not interfere with the in vitro activities of most antibiotics. GT160-246 offers a novel, nonantimicrobial treatment of
C. difficile
disease in humans.
New
erm
Gene in
Staphylococcus aureus
Clinical Isolates
Authors: Matsuoka Mayumi , Inoue Matsuhisa , Nakajima Yoshinori , Endo Yoshihiro 
Published: July 2002

ABSTRACT

We have identified
erm
(Y), a novel gene class that was originally designated
ermGM
, from a
Staphylococcus aureus
strain that has a plasmid that also harbors
msr
(A) and
mph
(C), genes that encode an efflux mechanism and a putative phosphorylase, respectively. The nucleotide and deduced amino acid sequences of
erm
(Y) were 81 and 76% identical to those of
erm
(T), respectively.
Efficacy of TAK-457, a Novel Intravenous Triazole, against Invasive Pulmonary Aspergillosis in Neutropenic Mice
Authors: Hayashi Ryogo , Kitamoto Naomi , Iizawa Yuji , Ichikawa Takashi , Itoh Katsumi , Kitazaki Tomoyuki , Okonogi Kenji 
Published: July 2002

ABSTRACTTAK-457 is an injectable prodrug of TAK-456, which is a novel oral triazole compound with potent antifungal activity. The in vivo efficacy of TAK-457 was evaluated in two models of invasive pulmonary aspergillosis with CDF1mice and CBA/J mice with transient neutropenia induced by cyclophosphamide. Against the infection in CDF1mice, treatment with 10 mg of TAK-457 and 1 mg of amphotericin B/kg reduced the fungal burden in lungs and rescued all mice. In the infection model with CBA/J mice, TAK-457 at a dose of 10 mg/kg significantly prolonged the survival time of mice, showing significant reduction of lung chitin levels and the plasma β-d-glucan levels. On the other hand, amphotericin B at 1 mg/kg which was a maximum tolerable dose showed slight but not significant prolongation of survival time of mice, although it also reduced the lung chitin levels and the plasma β-d-glucan levels to a lower extent but still significantly. These results suggest that TAK-457 is a promising candidate for development for the treatment of invasive aspergillosis in humans.
Strong Antifungal Activity of SS750, a New Triazole Derivative, Is Based on Its Selective Binding Affinity to Cytochrome P450 of Fungi
Authors: Matsumoto Masaru , Ishida Kazuya , Konagai Akihiro , Maebashi Kazunori , Asaoka Takemitsu 
Published: July 2002

ABSTRACT

SS750 [(
R
)-(−)-2-(2,4-difluorophenyl)-1-(ethylsulfonyl)-1,1-difluoro-3-(1
H
-1,2,4-triazol-1-yl)-2-propanol] is a new triazole, and its potential as an antifungal agent was evaluated by in vitro and in vivo studies. In a comparison of the MICs at which 50% of isolates are inhibited (MIC
50
s) for all strains of
Candida
species and
Cryptococcus neoformans
tested, SS750 was four times or more active than fluconazole and had activity comparable to that of itraconazole. The most important advantage of SS750 was that, when the MIC
90
s were compared, SS750 had 64 and 32 times greater antifungal activities than fluconazole against
Candida krusei
and
Candida glabrata
, respectively, which are intrinsically less susceptible to fluconazole. In cyclophosphamide-immunosuppressed mouse models of systemic and pulmonary candidiasis caused by
C. albicans
, oral SS750 prolonged the number of days of survival of infected animals in a dose-dependent manner and was 4 and ≥64 times more potent than fluconazole and itraconazole, respectively. In a safety profile, SS750, like fluconazole, had less of an affinity for binding to mammalian cytochrome P450 compared with that of ketoconazole, despite its strong affinity for binding to fungal cytochrome P450. The mechanism for the increased in vitro antifungal activity of SS750 against
C. krusei
is partially due to the potent inhibitory activity (3.7 times versus that of fluconazole) of
C. krusei
cytochrome P450 sterol 14α-demethylase; SS750 showed a strong affinity for binding to cytochrome P450 of
C. krusei
, indicating that SS750 acts by inhibiting the cytochrome P450 sterol 14α-demethylase of fungal cells.
In Vitro Activities of BAL9141, a Novel Broad-Spectrum Pyrrolidinone Cephalosporin, against Gram-Negative Nonfermenters
Authors: Zbinden R. , Pünter V. , von Graevenitz A. 
Published: July 2002

ABSTRACT

The activities of BAL9141 (formerly Ro 63-9141), a novel pyrrolidinone-3-ylidenemethyl cephalosporin, against 244 strains of gram-negative nonfermenters were evaluated. The overall MIC at which 50% of isolates are inhibited (MIC
50
) and the overall MIC
90
were 2 and 64 μg/ml, respectively, which are similar to those of imipenem, lower than those of the other cephalosporins tested, amoxicillin, and the ticarcillin-clavulanic acid combination, and much higher than those of ciprofloxacin. BAL9141 shows species-dependent activity in vitro against a variety of gram-negative nonfermentative pathogens.
In Vitro Activities of Peptide Deformylase Inhibitors against Gram-Positive Pathogens
Authors: Wise R. , Andrews J. M. , Ashby J. 
Published: July 2002

ABSTRACT

The activities of six peptide deformylase (PDF) inhibitors against 107 respiratory tract pathogens were studied and compared to those of ciprofloxacin and amoxicillin-clavulanate. Against
Streptococcus
pneumoniae
, BB-83698 and BB-83815 were the most active PDF inhibitors (MIC at which 90% of the organisms tested were inhibited [MIC
90
], 0.25 μg/ml). Five of the agents showed similar activity against
Moraxella
catarrhalis
(MIC
90
, 0.12 μg/ml). All PDF inhibitors were less active against
Haemophilus
influenzae
; BB-3497 was the most active agent (MIC
90
, 2 μg/ml). Five agents were studied against
Chlamydia
spp. and showed activity similar to that of ciprofloxacin (MIC, 0.5 to 4 μg/ml). This study demonstrates that PDF inhibitors have the potential to be developed for the treatment of respiratory tract infections.
Novel Type of Staphylococcal Cassette Chromosome
mec
Identified in Community-Acquired Methicillin-Resistant
Staphylococcus aureus
Strains
Authors: Ma Xiao Xue , Ito Teruyo , Tiensasitorn Chuntima , Jamklang Mantana , Chongtrakool Piriyaporn , Boyle-Vavra Susan , Daum Robert S. , Hiramatsu Keiichi 
Published: July 2002

ABSTRACT

We identified a new type of staphylococcal cassette chromosome
mec
(SCC
mec
) from two community-acquired methicillin-resistant
Staphylococcus aureus
(MRSA) strains. The novel element, designated type IV SCC
mec
, had a unique combination of the class B
mec
gene complex and the type 2
ccr
gene complex and was much smaller in size (21 to 24 kb) than previously identified SCC
mec
elements of hospital-acquired MRSA. Consistent with the strains' susceptibilities to various non-β-lactam antibiotics, the type IV SCC
mec
was devoid of any antibiotic resistance genes other than the
mecA
gene.
In Vitro and In Vivo Activities of a Novel Cephalosporin, BMS-247243, against Methicillin-Resistant and -Susceptible Staphylococci
Authors: Fung-Tomc Joan C. , Clark Junius , Minassian Beatrice , Pucci Michael , Tsai Yuan-Hwang , Gradelski Elizabeth , Lamb Lucinda , Medina Ivette , Huczko Elizabeth , Kolek Benjamin , Chaniewski Susan , Ferraro Cheryl , Washo Thomas , Bonner Daniel P. 
Published: July 2002

ABSTRACT

The recent emergence of methicillin-resistant
Staphylococcus aureus
(MRSA) with decreased susceptibility to vancomycin has intensified the search for alternative therapies for the treatment of infections caused by this organism. One approach has been to identify a β-lactam with improved affinity for PBP 2a, the target enzyme responsible for methicillin resistance in staphylococci. BMS-247243 is such a candidate, with MICs that inhibit 90% of isolates tested (MIC
90
s) of 4, 2, and 8 μg/ml for methicillin-resistant strains of
S. aureus
,
S. epidermidis
, and
S. haemolyticus
, respectively, as determined on plates with Mueller-Hinton agar and 2% NaCl. The BMS-247243 MICs for MRSA were minimally affected by the susceptibility testing conditions (inoculum size, prolonged incubation, addition of salt to the test medium) or by staphylococcal β-lactamases. BMS-247243 MIC
90
s for methicillin-susceptible staphylococcal species ranged from ≤0.25 to 1 μg/ml. The BMS-247243 MIC
90
for β-lactamase-producing
S. aureus
strains was fourfold higher than that for β-lactamase-nonproducing strains. BMS-247243 is hydrolyzed by staphylococccal β-lactamases at 4.5 to 26.2% of the rates measured for cephaloridine. The affinity of BMS-247243 for PBP 2a was >100-fold better than that of methicillin or cefotaxime. BMS-247243 is bactericidal for MRSA, killing the bacteria twice as fast as vancomycin. These in vitro activities of BMS-247243 correlated with its in vivo efficacy against infections in animals, including the neutropenic murine thigh and rabbit endocarditis models involving MRSA strains. In conclusion, BMS-247243 has in vitro and in vivo activities against methicillin-resistant staphylococci and thus may prove to be useful in the treatment of infections caused by these multidrug-resistant organisms.
Purification, Characterization, and Identification of Novel Inhibitors of the β-Ketoacyl-Acyl Carrier Protein Synthase III (FabH) from
Staphylococcus aureus
Authors: He Xin , Reynolds Kevin A. 
Published: July 2002

ABSTRACT

Staphylococcus aureus
is a versatile and dangerous pathogen and one of the major causes of community-acquired and hospital-acquired infections. The rise of multidrug-resistant strains of
S. aureus
requires the development of new antibiotics with previously unexploited mechanisms of action, such as inhibition of the β-ketoacyl-acyl carrier protein (ACP) synthase III (FabH). This enzyme initiates fatty acid biosynthesis in a bacterial type II fatty acid synthase, catalyzing a decarboxylative condensation between malonyl-ACP and an acyl coenzyme A (CoA) substrate and is essential for viability. We have identified only one
fabH
in the genome of
S. aureus
and have shown that it encodes a protein with 57, 40, and 34% amino acid sequence identity with the FabH proteins of
Bacillus subtilis
(bFabH1),
Escherichia coli
(ecFabH), and
Mycobacterium tuberculosis
(mtFabH). Additional genomic sequence analysis revealed that this
S. aureus
FabH (saFabH) is not mutated in certain methicillin-resistant
S. aureus
(MRSA) and vancomycin-resistant
S. aureus
(VRSA) strains. saFabH was expressed in
E. coli
with an N-terminal polyhistidine tag and subsequently purified by metal chelate and size exclusion chromatography. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a molecular mass of 37 kDa, while gel filtration demonstrated a mass of 66.7 kDa, suggesting a noncovalent homodimeric structure for saFabH. The apparent

K
m

for malonyl-ACP was 1.76 ± 0.40 μM, and the enzyme was active with acetyl-CoA (
k
cat
, 16.18 min
−1
;

K
m

, 6.18 ± 0.9 μM), butyryl-CoA (
k
cat
, 42.90 min
−1
;

K
m

, 2.32 ± 0.12 μM), and isobutyryl-CoA (
k
cat
, 98.0 min
−1
;

K
m

, 0.32 ± 0.04 μM). saFabH was weakly inhibited by thiolactomycin (50% inhibitory concentration [IC
50
], >100 μM) yet was efficiently inhibited by two new FabH inhibitors, 5-chloro-4-phenyl-[1,2]-dithiol-3-one (IC
50
, 1.87 ± 0.10 μM) and 4-phenyl-5-phenylimino-[1,2,4]dithiazolidin-3-one (IC
50
, 0.775 ± 0.08 μM).
In Vitro and In Vivo Activities of Posaconazole against
Coccidioides immitis
Authors: González Gloria M. , Tijerina Rolando , Najvar Laura K. , Bocanegra Rosie , Rinaldi Michael , Loebenberg David , Graybill John R. 
Published: July 2002

ABSTRACT

Posaconazole (SCH 56592) was tested against 25 strains of
Coccidioides immitis
to determine their in vitro susceptibilities. The geometric mean 48-h MIC of posaconazole (POSA) was 0.5 μg/ml, the MIC range was 0.25 to 1 μg/ml, and the MIC at which 50% of the isolates tested are inhibited (MIC
50
) and the MIC
90
were 0.5 and 1 μg/ml, respectively. The geometric mean 48-h MIC of itraconazole (ITRA) was 0.23 μg/ml, the MIC range was 0.125 to 0.5 μg/ml, and the MIC
50
and MIC
90
were both 0.25 μg/ml. Two strains of
C. immitis
were selected for in vivo studies on the basis of the POSA 48-h MICs for the isolates. POSA orally administered at 0.01, 0.1, 0.5, 1, 5, and 10 mg/kg of body weight/day was compared with ITRA administered at 10 and 30 mg/kg three times a day. The spleens and livers of mice that died or survived to day 50 were removed to measure the fungal burdens. Mice had ≥90% survival when they were treated with ≥0.5 mg of POSA per kg or 30 mg of ITRA per kg. Cultures of whole spleens and livers from mice treated with 10 mg of POSA per kg showed ≥70% sterilization. No sterilization of whole spleens and livers from mice treated with ITRA was seen. POSA displayed potent in vivo activity against the two strains of
C. immitis
tested.
Pharmacokinetics of Piperacillin-Tazobactam in Anuric Intensive Care Patients during Continuous Venovenous Hemodialysis
Authors: Mueller Silke C. , Majcher-Peszynska Jolanta , Hickstein Heiko , Francke Astrid , Pertschy Annette , Schulz Martin , Mundkowski Ralf , Drewelow Bernd 
Published: July 2002

ABSTRACTThe pharmacokinetics of piperacillin-tazobactam were investigated in eight anuric intensive care patients treated by continuous venovenous hemodialysis (CVVHD). The elimination half-life of piperacillin was 4.3 ± 1.2 h, and that of tazobactam was 5.6 ± 1.3 h. The contribution of CVVHD to the overall elimination was relevant (>25%) for both drugs.
In Vitro Activities of Novel Nonfluorinated Quinolones PGE 9262932 and PGE 9509924 against Clinical Isolates of
Staphylococcus aureus
and
Streptococcus pneumoniae
with Defined Mutations in DNA Gyrase and Topoisomerase IV
Authors: Jones Mark E. , Critchley Ian A. , Karlowsky James A. , Blosser-Middleton Renée S. , Schmitz Franz-Josef , Thornsberry Clyde , Sahm Daniel F. 
Published: July 2002

ABSTRACT

Two 8-methoxy nonfluorinated quinolones (NFQs), PGE 9262932 and PGE 9509924, were tested against contemporary clinical isolates of
Staphylococcus aureus
(
n
= 122) and
Streptococcus pneumoniae
(
n
= 69) with genetically defined quinolone resistance-determining regions (QRDRs). For
S. aureus
isolates with wild-type (WT) sequences at the QRDRs, the NFQs demonstrated activities 4- to 32-fold more potent (MICs at which 90% of isolates are inhibited [MIC
90
s], 0.03 μg/ml) than those of moxifloxacin (MIC
90
, 0.12 μg/ml), gatifloxacin (MIC
90
, 0.25 μg/ml), levofloxacin (MIC
90
, 0.25 μg/ml), and ciprofloxacin (MIC
90
, 1 μg/ml). Against
S. pneumoniae
isolates with WT sequences at
gyrA
and
parC
, the NFQs PGE 9262932 (MIC
90
, 0.03 μg/ml) and PGE 9509924 (MIC
90
, 0.12 μg/ml) were 8- to 64-fold and 2- to 16-fold more potent, respectively, than moxifloxacin (MIC
90
, 0.25 μg/ml), gatifloxacin (MIC
90
, 0.5 μg/ml), levofloxacin (MIC
90
, 2 μg/ml), and ciprofloxacin (MIC
90
, 2 μg/ml). The MICs of all agents were elevated for
S. aureus
isolates with alterations in GyrA (Glu88Lys or Ser84Leu) and GrlA (Ser80Phe) and
S. pneumoniae
isolates with alterations in GyrA (Ser81Phe or Ser81Tyr) and ParC (Ser79Phe or Lys137Asn). Fluoroquinolone MICs for
S. aureus
strains with double alterations in GyrA combined with double alterations in GrlA were ≥32 μg/ml, whereas the MICs of the NFQs for strains with these double alterations were 4 to 8 μg/ml. The PGE 9262932 and PGE 9509924 MICs for the
S. pneumoniae
isolates did not exceed 0.5 and 1 μg/ml, respectively, even for isolates with GyrA (Ser81Phe) and ParC (Ser79Phe) alterations, for which levofloxacin MICs were >16 μg/ml. No difference in the frequency of selection of mutations (<10
−8
at four times the MIC) in wild-type or first-step mutant isolates of
S. aureus
or
S. pneumoniae
was detected for the two NFQs. On the basis of their in vitro activities, these NFQ agents show potential for the treatment of infections caused by isolates resistant to currently available fluoroquinolones.
CAU-1, a Subclass B3 Metallo-β-Lactamase of Low Substrate Affinity Encoded by an Ortholog Present in theCaulobacter crescentusChromosome
Authors: Docquier Jean-Denis , Pantanella Fabrizio , Giuliani Francesco , Thaller Maria Cristina , Amicosante Gianfranco , Galleni Moreno , Frère Jean-Marie , Bush Karen , Rossolini Gian Maria 
Published: July 2002

ABSTRACTThe sequenced chromosome ofCaulobacter crescentusCB15 encodes a hypothetical protein that exhibits significant similarity (30 to 35% identical residues) to metallo-β-lactamases of subclass B3. An allelic variant of this gene (divergent by 3% of its nucleotides) was cloned inEscherichia colifromC. crescentustype strain DSM4727. Expression studies confirmed the metallo-β-lactamase activity of its product, CAU-1. The enzyme produced inE. coliwas purified by two ion-exchange chromatography steps. CAU-1 contains a 29-kDa polypeptide with an alkaline isoelectric pH (>9), and unlike the L1 enzyme ofStenotrophomonas maltophilia, the native form is monomeric. Kinetic analysis revealed a preferential activity toward penicillins, carbapenems, and narrow-spectrum cephalosporins, while oxyimino cephalosporins were poorly or not hydrolyzed. Affinities for the various β-lactams were poor overall (Kmvalues were always >100 μM and often >400 μM). The interaction with divalent ion chelators appeared to occur by a mechanism similar to that prevailing in other members of subclass B3. InC. crescentus, the CAU-1 enzyme is produced independently of β-lactam exposure and, interestingly, theblaCAUdeterminant is bracketed by three other genes, including two genes encoding enzymes involved in methionine biosynthesis and a gene encoding a putative transcriptional regulator, in an operon-like structure. The CAU-1 enzyme is the first example of a metallo-β-lactamase in a member of the α subdivision of the classProteobacteria.
Activities of Therapeutic Agents and Myristamidopropyl Dimethylamine against
Acanthamoeba
Isolates
Authors: Kilvington Simon , Hughes Reanne , Byas James , Dart John 
Published: July 2002

ABSTRACT

The activities of therapeutic agents and myristamidopropyl dimethylamine (MAPD) against
Acanthamoeba
strains recalcitrant to medical therapy were studied. MAPD minimum cysticidal concentrations were 6.25 to 25 μg/ml; 10 to 30 μg/ml gave at least a 3-log cyst kill after 6 h, and 50 and 100 μg/ml gave at least a 3-log cyst kill within 2 and 1 h, respectively.
Molecular Genetic Manipulation of Truncated Cry1C Protein Synthesis in
Bacillus thuringiensis
To Improve Stability and Yield
Authors: Park Hyun-Woo , Bideshi Dennis K. , Federici Brian A. 
Published: July 2002

ABSTRACT

Cry1 protoxins of
Bacillus thuringiensis
are insecticidal 135-kDa proteins synthesized and assembled into parasporal crystals during sporulation. After ingestion, these crystals dissolve in the midgut and active toxins with molecular masses of about 65-kDa are released from the N-terminal half of the molecule by midgut proteases. Direct synthesis of the toxin-containing N-terminal half of Cry1 molecules using recombinant DNA techniques results in a low level of unstable truncated proteins that do not crystallize. In the present study, inclusions of truncated Cry1C (Cry1C-t) were obtained by combining genetic elements from other endotoxin genes and operons that enhance Cry protein synthesis and crystallization. Increased levels of Cry1C-t synthesis were achieved by using
cyt1A
promoters to drive expression of the 5′ half of
cry1C
that included in the construct the 5′
cry3A
STAB-SD mRNA stabilizing sequence and the 3′ stem-loop transcription terminator. RNA dot blot analysis showed that the STAB-SD and 3′ transcriptional termination sequences were important for stabilization of truncated
cry1C
(
cry1C-t
) mRNA. A low level of
cry1C-t
mRNA was present when only the
cyt1A
promoters were used to express
cry1C-t
, but no accumulation of Cry1C-t was detected in Western blots. The orientation of the transcription terminator was important to enhancing Cry1C-t synthesis. Inclusion of the 20- and 29-kDa helper protein genes in
cry1C-t
constructs further enhanced synthesis. The Cry1C-t protein was toxic to
Spodoptera exigua
larvae, though the toxicity (50% lethal concentration [LC
50
] = 13.2 μg/ml) was lower than that of full-length Cry1C (LC
50
= 1.8 μg/ml). However, transformation of the HD1 isolate of
B. thuringiensis
subsp.
kurstaki
with the
cry1C-t
construct enhanced its toxicity to
S. exigua
as much as fourfold.