scholarly journals Resistance to Bacillus thuringiensis Toxin Cry2Ab in Trichoplusia ni Is Conferred by a Novel Genetic Mechanism

2015 ◽  
Vol 81 (15) ◽  
pp. 5184-5195 ◽  
Author(s):  
Xiaozhao Song ◽  
Wendy Kain ◽  
Douglas Cassidy ◽  
Ping Wang
Keyword(s):  
Alkaline Phosphatase ◽  
Bacillus Thuringiensis ◽  
Trichoplusia Ni ◽  
Genetic Linkage ◽  
Genetic Mechanism ◽  
Cross Resistance ◽  
Genetic Linkage Analysis ◽  
Recessive Trait ◽  
Content Type ◽  
Significant Difference

ABSTRACTThe resistance to theBacillus thuringiensis(Bt) toxin Cry2Ab in a greenhouse-originatedTrichoplusia nistrain resistant to both Bt toxins Cry1Ac and Cry2Ab was characterized. Biological assays determined that the Cry2Ab resistance in theT. nistrain was a monogenic recessive trait independent of Cry1Ac resistance, and there existed no significant cross-resistance between Cry1Ac and Cry2Ab inT. ni. From the dual-toxin-resistantT. nistrain, a strain resistant to Cry2Ab only was isolated, and the Cry2Ab resistance trait was introgressed into a susceptible laboratory strain to facilitate comparative analysis of the Cry2Ab resistance with the susceptibleT. nistrain. Results from biochemical analysis showed no significant difference between the Cry2Ab-resistant and -susceptibleT. nilarvae in midgut proteases, including caseinolytic proteolytic activity and zymogram profile and serine protease activities, in midgut aminopeptidase and alkaline phosphatase activity, and in midgut esterases and hemolymph plasma melanization activity. For analysis of genetic linkage of Cry2Ab resistance with potential Cry toxin receptor genes, molecular markers for the midgut cadherin, alkaline phosphatase (ALP), and aminopeptidase N (APN) genes were identified between the original greenhouse-derived dual-toxin-resistant and the susceptible laboratoryT. nistrains. Genetic linkage analysis showed that the Cry2Ab resistance inT. niwas not genetically associated with the midgut genes coding for the cadherin, ALP, and 6 APNs (APN1 to APN6) nor associated with the ABC transporter geneABCC2. Therefore, the Cry2Ab resistance inT. niis conferred by a novel but unknown genetic mechanism.

scholarly journals Mechanism of Resistance to Bacillus thuringiensis Toxin Cry1Ac in a Greenhouse Population of the Cabbage Looper, Trichoplusia ni

2006 ◽  
Vol 73 (4) ◽  
pp. 1199-1207 ◽  
Author(s):  
Ping Wang ◽  
Jian-Zhou Zhao ◽  
Ana Rodrigo-Sim�n ◽  
Wendy Kain ◽  
Alida F. Janmaat ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Binding Site ◽  
Trichoplusia Ni ◽  
Specific Binding ◽  
Laboratory Strain ◽  
Cabbage Looper ◽  
Cross Resistance ◽  
Resistance Pattern ◽  
Recessive Trait ◽  
Mechanism Of Resistance

ABSTRACT The cabbage looper, Trichoplusia ni, is one of only two insect species that have evolved resistance to Bacillus thuringiensis in agricultural situations. The trait of resistance to B. thuringiensis toxin Cry1Ac from a greenhouse-evolved resistant population of T. ni was introgressed into a highly inbred susceptible laboratory strain. The resulting introgression strain, GLEN-Cry1Ac-BCS, and its nearly isogenic susceptible strain were subjected to comparative genetic and biochemical studies to determine the mechanism of resistance. Results showed that midgut proteases, hemolymph melanization activity, and midgut esterase were not altered in the GLEN-Cry1Ac-BCS strain. The pattern of cross-resistance of the GLEN-Cry1Ac-BCS strain to 11 B. thuringiensis Cry toxins showed a correlation of the resistance with the Cry1Ab/Cry1Ac binding site in T. ni. This cross-resistance pattern is different from that found in a previously reported laboratory-selected Cry1Ab-resistant T. ni strain, evidently indicating that the greenhouse-evolved resistance involves a mechanism different from the laboratory-selected resistance. Determination of specific binding of B. thuringiensis toxins Cry1Ab and Cry1Ac to the midgut brush border membranes confirmed the loss of midgut binding to Cry1Ab and Cry1Ac in the resistant larvae. The loss of midgut binding to Cry1Ab/Cry1Ac is inherited as a recessive trait, which is consistent with the recessive inheritance of Cry1Ab/Cry1Ac resistance in this greenhouse-derived T. ni population. Therefore, it is concluded that the mechanism for the greenhouse-evolved Cry1Ac resistance in T. ni is an alteration affecting the binding of Cry1Ab and Cry1Ac to the Cry1Ab/Cry1Ac binding site in the midgut.

scholarly journals Long inverted repeats around the chromosome replication terminus in the model strain Bacillus thuringiensis serovar israelensis BGSC 4Q7

2020 ◽  
Vol 6 (12) ◽  
Author(s):  
Alexander Bolotin ◽  
Benoit Quinquis ◽  
Hugo Roume ◽  
Michel Gohar ◽  
Didier Lereclus ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Type Species ◽  
Single Nucleotide Variants ◽  
Host Chromosome ◽  
Content Type ◽  
Link Type ◽  
Significant Difference ◽  
Extrachromosomal Element ◽  
Genome Restructuring ◽  
Replication Terminus

Bacillus thuringiensis serovar israelensis is the most widely used natural biopesticide against mosquito larvae worldwide. Its lineage has been actively studied and a plasmid-free strain, B . thuringiensis serovar israelensis BGSC 4Q7 (4Q7), has been produced. Previous sequencing of the genome of this strain has revealed the persistent presence of a 235 kb extrachromosomal element, pBtic235, which has been shown to be an inducible prophage, although three putative chromosomal prophages have been lost. Moreover, a 492 kb region, potentially including the standard replication terminus, has also been deleted in the 4Q7 strain, indicating an absence of essential genes in this area. We reanalysed the genome coverage distribution of reads for the previously sequenced variant strain, and sequenced two independently maintained samples of the 4Q7 strain. A 553 kb area, close to the 492 kb deletion, was found to be duplicated. This duplication presumably restored the equal sizes of the replichores, and a balanced functioning of replication termination. An analysis of genome assembly graphs revealed a transient association of the host chromosome with the pBtic235 element. This association may play a functional role in the replication of the bacterial chromosome, and the termination of this process in particular. The genome-restructuring events detected may modify the genetic status of cytotoxic or haemolytic toxins, potentially influencing strain virulence. Twelve of the single-nucleotide variants identified in 4Q7 were probably due to the procedure used for strain construction or were present in the precursor of this strain. No sequence variants were found in pBtic235, but the distribution of the corresponding 4Q7 reads indicates a significant difference from counterparts in natural B. thuringiensis serovar israelensis strains, suggesting a duplication or over-replication in 4Q7. Thus, the 4Q7 strain is not a pure plasmid-less offshoot, but a highly genetically modified derivative of its natural ancestor. In addition to potentially influencing virulence, genome-restructuring events can modify the replication termination machinery. These findings have potential implications for the conclusions of virulence studies on 4Q7 as a model, but they also raise interesting fundamental questions about the functioning of the Bacillus genome.

scholarly journals Characterization of Chimeric Bacillus thuringiensis Vip3 Toxins

2006 ◽  
Vol 73 (3) ◽  
pp. 956-961 ◽  
Author(s):  
Jun Fang ◽  
Xiaoli Xu ◽  
Ping Wang ◽  
Jian-Zhou Zhao ◽  
Anthony M. Shelton ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Trichoplusia Ni ◽  
European Corn Borer ◽  
Insect Pest ◽  
Chimeric Protein ◽  
Fall Armyworm ◽  
Terminal Region ◽  
Cabbage Looper ◽  
Cross Resistance ◽  
Corn Borer

ABSTRACT Bacillus thuringiensis vegetative insecticidal proteins (Vip) are potential alternatives for B. thuringiensis endotoxins that are currently utilized in commercial transgenic insect-resistant crops. Screening a large number of B. thuringiensis isolates resulted in the cloning of vip3Ac1. Vip3Ac1 showed high insecticidal activity against the fall armyworm Spodoptera frugiperda and the cotton bollworm Helicoverpa zea but very low activity against the silkworm Bombyx mori. The host specificity of this Vip3 toxin was altered by sequence swapping with a previously identified toxin, Vip3Aa1. While both Vip3Aa1 and Vip3Ac1 showed no detectable toxicity against the European corn borer Ostrinia nubilalis, the chimeric protein Vip3AcAa, consisting of the N-terminal region of Vip3Ac1 and the C-terminal region of Vip3Aa1, became insecticidal to the European corn borer. In addition, the chimeric Vip3AcAa had increased toxicity to the fall armyworm. Furthermore, both Vip3Ac1 and Vip3AcAa are highly insecticidal to a strain of cabbage looper (Trichoplusia ni) that is highly resistant to the B. thuringiensis endotoxin Cry1Ac, thus experimentally showing for the first time the lack of cross-resistance between B. thuringiensis Cry1A proteins and Vip3A toxins. The results in this study demonstrated that vip3Ac1 and its chimeric vip3 genes can be excellent candidates for engineering a new generation of transgenic plants for insect pest control.

scholarly journals Bacillus thuringiensis Vip3Aa Toxin Resistance in Heliothis virescens (Lepidoptera: Noctuidae)

2017 ◽  
Vol 83 (9) ◽  
Author(s):  
Brian R. Pickett ◽  
Asim Gulzar ◽  
Juan Ferré ◽  
Denis J. Wright
Keyword(s):  
Bacillus Thuringiensis ◽  
Heliothis Virescens ◽  
Insect Pests ◽  
Management Strategies ◽  
Resistance Management ◽  
Cross Resistance ◽  
Inheritance Of Resistance ◽  
Resistant Parent ◽  
Bt Crops ◽  
Content Type

ABSTRACT Laboratory selection with Vip3Aa of a field-derived population of Heliothis virescens produced >2,040-fold resistance in 12 generations of selection. The Vip3Aa-selected (Vip-Sel)-resistant population showed little cross-resistance to Cry1Ab and no cross-resistance to Cry1Ac. Resistance was unstable after 15 generations without exposure to the toxin. F1 reciprocal crosses between Vip3Aa-unselected (Vip-Unsel) and Vip-Sel insects indicated a strong paternal influence on the inheritance of resistance. Resistance ranged from almost completely recessive (mean degree of dominance [h] = 0.04 if the resistant parent was female) to incompletely dominant (mean h = 0.53 if the resistant parent was male). Results from bioassays on the offspring from backcrosses of the F1 progeny with Vip-Sel insects indicated that resistance was due to more than one locus. The results described in this article provide useful information for the insecticide resistance management strategies designed to overcome the evolution of resistance to Vip3Aa in insect pests. IMPORTANCE Heliothis virescens is an important pest that has the ability to feed on many plant species. The extensive use of Bacillus thuringiensis (Bt) crops or spray has already led to the evolution of insect resistance in the field for some species of Lepidoptera and Coleoptera. The development of resistance in insect pests is the main threat to Bt crops. The effective resistance management strategies are very important to prolong the life of Bt plants. Lab selection is the key step to test the assumption and predictions of management strategies prior to field evaluation. Resistant insects offer useful information to determine the inheritance of resistance and the frequency of resistance alleles and to study the mechanism of resistance to insecticides.

scholarly journals Aedes aegypti Membrane-Bound Alkaline Phosphatase Expressed in Escherichia coli Retains High-Affinity Binding for Bacillus thuringiensis Cry4Ba Toxin

2011 ◽  
Vol 77 (19) ◽  
pp. 6836-6840 ◽  
Author(s):  
Anon Thammasittirong ◽  
Manasave Dechklar ◽  
Somphob Leetachewa ◽  
Kusol Pootanakit ◽  
Chanan Angsuthanasombat
Keyword(s):  
Escherichia Coli ◽  
Alkaline Phosphatase ◽  
Bacillus Thuringiensis ◽  
Aedes Aegypti ◽  
Nitrilotriacetic Acid ◽  
Affinity Column ◽  
Dot Blot ◽  
Content Type ◽  
Binding Characteristics ◽  
High Affinity

ABSTRACTGlycosylphosphatidylinositol-linked alkaline phosphatase (GPI-ALP) from the epithelial membrane of the larval midgut ofAedes aegyptiwas previously identified as a functional receptor of theBacillus thuringiensisCry4Ba toxin. Here, heterologous expression inEscherichia coliof the cloned ALP, lacking the secretion signal and GPI attachment sequences, and assessment of its binding characteristics were further investigated. The 54-kDa His tag-fused ALP overexpressed as an inclusion body was soluble when phosphate buffer (pH 7.5) was supplemented with 8 M urea. After renaturation in a nickel-nitrilotriacetic acid (Ni-NTA) affinity column, the refolded ALP protein was able to retain its phosphatase activity. This refolded ALP also showed binding to the 65-kDa activated Cry4Ba toxin under nondenaturing (dot blot) conditions. Quantitative binding analysis using a quartz crystal microbalance revealed that the purified ALP immobilized on a gold electrode was bound by the Cry4Ba toxin in a stoichiometry of approximately 1:2 and with high affinity (dissociation constant [Kd] of ∼14 nM) which is comparable to that calculated from kinetic parameters (dissociation rate constant [koff]/binding constant [kon]). Altogether, the data presented here of theE. coli-expressed ALP fromA. aegyptiretaining high-affinity toxin binding support our notion that glycosylation of this receptor is not required for binding to its counterpart toxin, Cry4Ba.

scholarly journals Resistance of Trichoplusia ni Populations Selected by Bacillus thuringiensis Sprays to Cotton Plants Expressing Pyramided Bacillus thuringiensis Toxins Cry1Ac and Cry2Ab

2014 ◽  
Vol 81 (5) ◽  
pp. 1884-1890 ◽  
Author(s):  
Wendy Kain ◽  
Xiaozhao Song ◽  
Alida F. Janmaat ◽  
Jian-Zhou Zhao ◽  
Judith Myers ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Trichoplusia Ni ◽  
Resistance Mechanisms ◽  
Vegetable Production ◽  
Bt Cotton ◽  
Content Type ◽  
Bt Toxin ◽  
Bt Toxins ◽  
Cotton Plants ◽  
Incomplete Resistance

ABSTRACTTwo populations ofTrichoplusia nithat had developed resistance toBacillus thuringiensissprays (Bt sprays) in commercial greenhouse vegetable production were tested for resistance to Bt cotton (BollGard II) plants expressing pyramided Cry1Ac and Cry2Ab. TheT. nicolonies resistant toBacillus thuringiensisserovar kurstaki formulations were not only resistant to the Bt toxin Cry1Ac, as previously reported, but also had a high frequency of Cry2Ab-resistant alleles, exhibiting ca. 20% survival on BollGard II foliage. BollGard II-resistantT. nistrains were established by selection with BollGard II foliage to further remove Cry2Ab-sensitive alleles in theT. nipopulations. The BollGard II-resistant strains showed incomplete resistance to BollGard II, with adjusted survival values of 0.50 to 0.78 after 7 days. The resistance to the dual-toxin cotton plants was conferred by two genetically independent resistance mechanisms: one to Cry1Ac and one to Cry2Ab. The 50% lethal concentration of Cry2Ab for the resistant strain was at least 1,467-fold that for the susceptibleT. nistrain. The resistance to Cry2Ab in resistantT. niwas an autosomally inherited, incompletely recessive monogenic trait. Results from this study indicate that insect populations under selection by Bt sprays in agriculture can be resistant to multiple Bt toxins and may potentially confer resistance to multitoxin Bt crops.

scholarly journals Toxicity and Binding Studies of Bacillus thuringiensis Cry1Ac, Cry1F, Cry1C, and Cry2A Proteins in the Soybean Pests Anticarsia gemmatalis and Chrysodeixis (Pseudoplusia) includens

2017 ◽  
Vol 83 (11) ◽  
Author(s):  
Yolanda Bel ◽  
Joel J. Sheets ◽  
Sek Yee Tan ◽  
Kenneth E. Narva ◽  
Baltasar Escriche
Keyword(s):  
Bacillus Thuringiensis ◽  
Binding Sites ◽  
Specific Binding ◽  
Management Strategies ◽  
Anticarsia Gemmatalis ◽  
Cross Resistance ◽  
Binding Studies ◽  
Content Type ◽  
Bt Toxins ◽  
Competition Binding

ABSTRACT Anticarsia gemmatalis (velvetbean caterpillar) and Chrysodeixis includens (soybean looper, formerly named Pseudoplusia includens) are two important defoliating insects of soybeans. Both lepidopteran pests are controlled mainly with synthetic insecticides. Alternative control strategies, such as biopesticides based on the Bacillus thuringiensis (Bt) toxins or transgenic plants expressing Bt toxins, can be used and are increasingly being adopted. Studies on the insect susceptibilities and modes of action of the different Bt toxins are crucial to determine management strategies to control the pests and to delay outbreaks of insect resistance. In the present study, the susceptibilities of both soybean pests to the Bt toxins Cry1Ac, Cry1Fa, Cry1Ca, and Cry2Aa have been investigated. Bioassays performed in first-instar larvae showed that both insects are susceptible to all these toxins. Competition-binding studies carried out with Cry1Ac and Cry1Fa 125-iodine labeled proteins demonstrated the presence of specific binding sites for both of them on the midgut brush border membrane vesicles (BBMVs) of both A. gemmatalis and C. includens. Competition-binding experiments and specific-binding inhibition studies performed with selected sugars and lectins indicated that Cry1Ac and Cry1Fa share some, but not all, binding sites in the midguts of both insects. Also, the Cry1Ac- or Cry1Fa-binding sites were not shared with Cry1Ca or Cry2Aa in either soybean pest. This study contributes to the knowledge of Bt toxicity and midgut toxin binding sites in A. gemmatalis and C. includens and sheds light on the cross-resistance potential of Cry1Ac, Cry1Fa, Cry1Ca, and Cry2Aa Bt proteins as candidate proteins for Bt-pyramided crops. IMPORTANCE In the present study, the toxicity and the mode of action of the Bacillus thuringiensis (Bt) toxins Cry1Ac, Cry1Fa, Cry1Ca, and Cry2Aa in Anticarsia gemmatalis and Chrysodeixis includens (important defoliating pests of soybeans) have been investigated. These studies are crucial for determining management strategies for pest control. Bioassays showed that both insects were susceptible to the toxins. Competition-binding studies demonstrated the presence of Cry1Fa- and Cry1Ac-specific binding sites in the midguts of both pests. These results, together with the results from binding inhibition studies performed with sugars and lectins, indicated that Cry1Ac and Cry1Fa share some, but not all, binding sites, and that they were not shared with Cry1Ca or Cry2Aa in either soybean pest. This study contributes to the knowledge of Bt toxicity in A. gemmatalis and C. includens and sheds light on the cross-resistance potential of Cry1Ac, Cry1Fa, Cry1Ca, and Cry2Aa Bt proteins as candidate proteins for Bt-pyramided crops.

scholarly journals Differential Role of Manduca sexta Aminopeptidase-N and Alkaline Phosphatase in the Mode of Action of Cry1Aa, Cry1Ab, and Cry1Ac Toxins from Bacillus thuringiensis

2013 ◽  
Vol 79 (15) ◽  
pp. 4543-4550 ◽  
Author(s):  
Biviana Flores-Escobar ◽  
Hector Rodríguez-Magadan ◽  
Alejandra Bravo ◽  
Mario Soberón ◽  
Isabel Gómez
Keyword(s):  
Alkaline Phosphatase ◽  
Bacillus Thuringiensis ◽  
Larval Development ◽  
Manduca Sexta ◽  
Mode Of Action ◽  
Membrane Vesicles ◽  
Aminopeptidase N ◽  
Content Type ◽  
Insecticidal Effect ◽  
Protein Levels

ABSTRACTAminopeptidase-N (APN1) and alkaline phosphatase (ALP) proteins located in the midgut epithelium ofManduca sextahave been implicated as receptors for Cry1Aa, Cry1Ab, and Cry1Ac insecticidal proteins produced byBacillus thuringiensissubsp.kurstaki. In this study, we analyzed the roles of ALP and APN1 in the toxicity of these three Cry1A proteins. Ligand blot analysis using brush border membrane vesicles ofM. sextashowed that Cry1Aa and Cry1Ab bind preferentially to ALP during early instars while binding to APN was observed after the third instar of larval development. Cry1Ac binds to APN throughout all larval development, with no apparent binding to ALP. ALP was cloned fromM. sextamidgut RNA and expressed inEscherichia coli. Surface plasmon resonance binding analysis showed that recombinant ALP binds to Cry1Ac with 16-fold lower affinity than to Cry1Aa or Cry1Ab. Downregulation of APN1 and ALP expression by RNA interference (RNAi) using specific double-stranded RNA correlated with a reduction of transcript and protein levels. Toxicity analysis of the three Cry1A proteins in ALP- or APN1-silenced larvae showed that Cry1Aa relies similarly on both receptor molecules for toxicity. In contrast, RNAi experiments showed that ALP is more important than APN for Cry1Ab toxicity, while Cry1Ac relied principally on APN1. These results indicated that ALP and APN1 have a differential role in the mode of action of Cry1A toxins, suggesting thatB. thuringiensissubsp.kurstakiproduces different Cry1A toxins that in conjunction target diverse midgut proteins to exert their insecticidal effect.

scholarly journals Insecticidal Activity of Bacillus thuringiensis Cry1Bh1 against Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae) and Other Lepidopteran Pests

2013 ◽  
Vol 79 (24) ◽  
pp. 7590-7597 ◽  
Author(s):  
Justin Lira ◽  
Jeff Beringer ◽  
Stephanie Burton ◽  
Samantha Griffin ◽  
Joel Sheets ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Insect Resistance ◽  
Ostrinia Nubilalis ◽  
Binding Sites ◽  
Membrane Binding ◽  
Cross Resistance ◽  
Content Type ◽  
Lepidopteran Pests ◽  
Resistant Strains ◽  
Membrane Binding Sites

ABSTRACTBacillus thuringiensisis an important source of insect resistance traits in commercial crops. In an effort to prolongB. thuringiensistrait durability, insect resistance management programs often include combinations of insecticidal proteins that are not cross resistant or have demonstrable differences in their site of action as a means to mitigate the development of resistant insect populations. In this report, we describe the activity spectrum of a novelB. thuringiensisCry protein, Cry1Bh1, against several lepidopteran pests, including laboratory-selectedB. thuringiensis-resistant strains ofOstrinia nubilalisandHeliothis virescensand progeny of field-evolvedB. thuringiensis-resistant strains ofPlutella xylostellaandSpodoptera frugiperda. Cry1Bh1 is active against susceptible andB. thuringiensis-resistant colonies ofO. nubilalis,P. xylostella, andH. virescensin laboratory diet-based assays, implying a lack of cross-resistance in these insects. However, Cry1Bh1 is not active against susceptible or Cry1F-resistantS. frugiperda. Further, Cry1Bh1 does not compete with Cry1Fa or Cry1Ab forO. nubilalismidgut brush border membrane binding sites. Cry1Bh1-expressing corn, while not completely resistant to insect damage, provided significantly better leaf protection against Cry1Fa-resistantO. nubilalisthan did Cry1Fa-expressing hybrid corn. The lack of cross-resistance with Cry1Ab and Cry1Fa along with independent membrane binding sites inO. nubilalismakes Cry1Bh1 a candidate to further optimize for in-plant resistance to this pest.

Gamma knife radiosurgery for intracranial metastatic melanoma: a 6-year experience

2002 ◽  
Vol 97 ◽  
pp. 494-498 ◽  
Author(s):  
Jorge Gonzalez-martinez ◽  
Laura Hernandez ◽  
Lucia Zamorano ◽  
Andrew Sloan ◽  
Kenneth Levin ◽  
...  
Keyword(s):  
Prognostic Factors ◽  
Brain Metastases ◽  
Metastatic Melanoma ◽  
Gamma Knife Radiosurgery ◽  
Tumor Control ◽  
Karnofsky Performance Scale ◽  
Content Type ◽  
Significant Difference ◽  
The Mean ◽  
Fine Print

Object. The purpose of this study was to evaluate retrospectively the effectiveness of stereotactic radiosurgery for intracranial metastatic melanoma and to identify prognostic factors related to tumor control and survival that might be helpful in determining appropriate therapy. Methods. Twenty-four patients with intracranial metastases (115 lesions) metastatic from melanoma underwent radiosurgery. In 14 patients (58.3%) whole-brain radiotherapy (WBRT) was performed, and in 12 (50%) chemotherapy was conducted before radiosurgery. The median tumor volume was 4 cm3 (range 1–15 cm3). The mean dose was 16.4 Gy (range 13–20 Gy) prescribed to the 50% isodose at the tumor margin. All cases were categorized according to the Recursive Partitioning Analysis classification for brain metastases. Univariate and multivariate analyses of survival were performed to determine significant prognostic factors affecting survival. The mean survival was 5.5 months after radiosurgery. The analyses revealed no difference in terms of survival between patients who underwent WBRT or chemotherapy and those who did not. A significant difference (p < 0.05) in mean survival was observed between patients receiving immunotherapy or those with a Karnofsky Performance Scale (KPS) score of greater than 90. Conclusions. The treatment with systemic immunotherapy and a KPS score greater than 90 were factors associated with a better prognosis. Radiosurgery for melanoma-related brain metastases appears to be an effective treatment associated with few complications.

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