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B A Federici

Publications and source records attributed to B A Federici.

At least 19 recordsLinked to original sources
PubMed2005

Characteristics of pathogenic and mutualistic relationships of ascoviruses in field populations of parasitoid wasps.

Ascoviruses are disseminated among larvae in lepidopteran populations by parasitic wasps during oviposition. Ascovirus relationships with these wasps vary from pathogenic to mutualistic, and experimentally can be shown possibly to be commensal non-pathogenic virus having little or no effect. Most ascoviruses are pathogens that female wasps vector mechanically. Other ascoviruses have a more intimate relationship with their wasp vectors in that their genome is stably maintained in all wasp nuclei through several generations by vertical transmission. In this relationship, these viruses are mutualistic, enhancing the successful development of the wasp larvae by suppressing lepidopteran defence mechanisms. The DpAV4 ascovirus is a mutualist in certain Diadromus wasps but is pathogenic or not when vectored by other species of this genus. These various biologies suggest that ascovirus/wasp relationships depend on wasp regulatory factors that control virus replication. Thus, certain ascoviruses can potentially have either a pathogenic, mutualistic, or non-pathogenic relationship with a specific wasp vector, the type of relationship being dependent upon the species system in which the relationship evolved. Finally, because ascoviruses appear to be related to ichnoviruses (Polydnaviridae), the DpAV4/Diadromus system constitutes a possible interesting intermediate between the pathogenic ascoviruses and symbiotic viruses that evolved to be ichnoviruses.

Animals↗
PubMed2003

Origin and evolution of polydnaviruses by symbiogenesis of insect DNA viruses in endoparasitic wasps.

During oviposition, many endoparasitic wasps inject virus-like particles into their insect hosts that enable these parasitoids to evade or directly suppress their hosts' immune system, especially encapsulation by hemocytes. These particles are defined as virions that belong to viruses of the two genera that comprise the family Polydnaviridae, bracoviruses (genus Bracovirus) transmitted by braconid wasps, and ichnoviruses (genus Ichnovirus) transmitted by ichneumonid wasps. Structurally, bracovirus virions resemble nudivirus and baculovirus virions (family Baculoviridae), and ichnovirus virions resemble those of ascoviruses (family Ascoviridae). Whereas nudiviruses, baculoviruses and ascoviruses replicate their DNA and produce progeny virions, polydnavirus DNA is integrated into and replicated from the wasp genome, which also directs virion synthesis. The structural similarity of polydnavirus virions to those of viruses that attack the wasps' lepidopteran hosts, along with polydnavirus transmission and replication biology, suggest that these viruses evolved from insect DNA viruses by symbiogenesis, the same process by which mitochondia and chloroplasts evolved from bacteria. Molecular evidence supporting this hypothesis comes from similarities among structural proteins of ascoviruses and the Campoletis sonorensis ichnovirus. Implications of this hypothesis are that polydnaviruses evolved from viruses, but are no longer viruses, and that DNA packaged into polydnavirus virions is not viral genomic DNA per se, but rather wasp genomic DNA consisting primarily of wasp genes and non-coding DNA. Thus, we suggest that a better understanding of polydnaviruses would result by viewing these not as viruses, but rather as a wasp organelle system that evolved to shuttle wasp genes and proteins into hosts to evade and suppress their immune response.

Amino Acid Sequence↗
PubMed2003

Recombinant bacteria for mosquito control.

Bacterial insecticides have been used for the control of nuisance and vector mosquitoes for more than two decades. Nevertheless, due primarily to their high cost and often only moderate efficacy, these insecticides remain of limited use in tropical countries where mosquito-borne diseases are prevalent. Recently, however, recombinant DNA techniques have been used to improve bacterial insecticide efficacy by markedly increasing the synthesis of mosquitocidal proteins and by enabling new endotoxin combinations from different bacteria to be produced within single strains. These new strains combine mosquitocidal Cry and Cyt proteins of Bacillus thuringiensis with the binary toxin of Bacillus sphaericus, improving efficacy against Culex species by 10-fold and greatly reducing the potential for resistance through the presence of Cyt1A. Moreover, although intensive use of B. sphaericus against Culex populations in the field can result in high levels of resistance, most of this can be suppressed by combining this bacterial species with Cyt1A; the latter enables the binary toxin of this species to enter midgut epithelial cells via the microvillar membrane in the absence of a midgut receptor. The availability of these novel strains and newly discovered mosquitocidal proteins, such as the Mtx toxins of B. sphaericus, offers the potential for constructing a range of recombinant bacterial insecticides for more effective control of the mosquito vectors of filariasis, Dengue fever and malaria.

Animals↗
PubMed2001

Construction and characterization of a recombinant Bacillus thuringiensis subsp. israelensis strain that produces Cry11B.

The mosquitocidal bacterium Bacillus thuringiensis subsp. israelensis (Bti) produces four major endotoxin proteins, Cry4A, Cry4B, Cry11A, and Cyt1A, and has toxicity in the range of many synthetic chemical insecticides. Cry11B, which occurs naturally in B. thuringiensis subsp. jegathesan, is a close relative of Cry11A, but is approximately 10-fold as toxic to Culex quinquefasciatus. To determine whether the addition of Cry11B to Bti would improve its toxicity, we produced this protein in Bti. High levels of Cry11B synthesis were obtained by expression of the cry11B gene under the control of cyt1A promoters and the STAB-SD sequence. This construct was cloned into the shuttle vector pHT3101, yielding the derivative plasmid pPFT11Bs, which was then transformed by electroporation into acrystalliferous (4Q7) and crystalliferous (IPS-82) strains of Bti. Synthesis of Cry11B in Bti 4Q7 produced crystals approximately 50% larger than those produced with its natural promoters without STAB-SD. However, less Cry11B was produced per unit culture medium with this construct than with the wild-type construct, apparently because the latter construct produced more cells per unit medium. Nevertheless, the Bti IPS-82 strain that produced Cry11B with pPFT11Bs was twice as toxic as the parental IPS-82 strain (LC(50) = 1.4 ng/ml versus 3.3 ng/ml, respectively) to fourth instars of C. quinquefasciatus. Against fourth instars of Aedes aegypti, no statistically significant difference between parental Bti IPS-82 (LC(50) = 4.7 ng/ml) and the Bti IPS-82 recombinant producing Cry11B (LC(50) = 3.5 ng/ml) was found in toxicity.

Aedes↗
PubMed2001

Cyt1A from Bacillus thuringiensis lacks toxicity to susceptible and resistant larvae of diamondback moth (Plutella xylostella) and pink bollworm (Pectinophora gossypiella).

We tested Cyt1Aa, a cytolytic endotoxin of Bacillus thuringiensis, against susceptible and Cry1A-resistant larvae of two lepidopteran pests, diamondback moth (Plutella xylostella) and pink bollworm (Pectinophora gossypiella). Unlike previous results obtained with mosquito and beetle larvae, Cyt1Aa alone or in combination with Cry toxins was not highly toxic to the lepidopteran larvae that we examined.

Animals↗
PubMed2000

Molecular characterization and phylogenetic analysis of the Harrisina brillians granulovirus granulin gene.

Well over 100 isolates of granulosis viruses (GVs), genus Granulovirus (family Baculoviridae), have been reported, all from lepidopterous insects. Three types of GVs are recognized, those of Type 1, which attack the fat body, Type 2, which attack most tissues, and Type 3, which attack only the midgut epithelium. To determine whether a correlation exists between tissue tropism and lepidopteran family phylogeny, the granulin gene of the Harrisina brillians (HbGV), a virus that attacks the midgut epithelium of H. brillians (family Zygaenidae) was cloned, sequenced, characterized, and compared with granulin genes of GVs that attack species of Tortricidae, Pieridae, and Noctuidae. The HbGV granulin gene encoded a peptide of 248 amino acids with a predicted Mr of 29.6 kDa, and shared a significant level of homology with other granulin (81-95% identical and 90-98% similar) and polyhedrin (49-58% identical and 62-72% similar) proteins. Phylogenetic analyses based on granulin and polyhedrin genes as well as on their 5'-untranslated sequences (5'-UTSs) indicated that HbGV was more closely related to GVs isolated from the tortricids, Cryptophlebia leucotreta (ClGV), Cydia pomonella (CpGV) and Choristoneura fumiferana (CfGV) than to other GVs and NPVs. This analysis provides preliminary evidence for a correlation between GV tissue tropism and the phylogeny of lepidopteran families, suggesting that GVs attacking species of Tortricidae and Zygaenidae are ancestral to those attacking species of the family Noctudiae.

5' Untranslated Regions↗
PubMed2000

The Trichoplusia ni granulovirus helicase is unable to support replication of Autographa californica multicapsid nucleopolyhedrovirus in cells and larvae of T. ni.

Baculovirus DNA helicases are essential for replication and are determinants of host range. Helicases of Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV) and Trichoplusia ni granulovirus (TnGV) differ markedly, although both viruses replicate efficiently in the cabbage looper, T. ni. To determine whether the TnGV helicase (P137) could support replication of AcMNPV in T. ni cells or larvae, the native AcMNPV helicase gene (p143) was disrupted and substituted with p137. P137 did not support replication when synthesized by the P143-deficient AcMNPV. Moreover, P137 did not inhibit AcMNPV replication when co-synthesized in the presence of the AcMNPV P143. These results suggest that although TnGV and AcMNPV replicate efficiently in T. ni, specific protein-protein or protein-DNA interactions between baculoviral helicases and viral-specific factors which form the replicase complex are required for virus replication. A novel and rapid method for disrupting AcMNPV genes in E. coli using the commercial Bac-to-Bac AcMNPV baculovirus expression vector is described.

Animals↗
PubMed2000

DNA-independent ATPase activity of the Trichoplusia ni granulovirus DNA helicase.

DNA helicases of baculoviruses are essential for virus replication and have been implicated as molecular determinants of host range. Although these proteins contain seven motifs (I, Ia, II-VI) characteristic of DNA helicases, the two most important characteristics of helicases - duplex-DNA unwinding and ATPase activity - have not been demonstrated. In the present study, a recombinant putative DNA helicase (rP137) of Trichoplusia ni granulovirus (TnGV) was purified from insect cells infected with a recombinant Autographa californica multicapsid nucleopolyhedrovirus that overproduced rP137. The rP137 protein exhibited an intrinsic DNA-independent ATPase activity that required Mg(2+) as a co-factor, an activity that was reduced in the presence of TnGV and phage lambda DNAs. These results provide further evidence that baculovirus helicase genes encode proteins with biochemical properties similar to those of classical DNA helicases.

Adenosine Triphosphatases↗
PubMed2000

Molecular genetic manipulation of truncated Cry1C protein synthesis in Bacillus thuringiensis to improve stability and yield.

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 microg/ml) was lower than that of full-length Cry1C (LC(50) = 1.8 microg/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.

Animals↗
PubMed2000

Cyt1A from Bacillus thuringiensis synergizes activity of Bacillus sphaericus against Aedes aegypti (Diptera: Culicidae).

Bacillus sphaericus is a mosquitocidal bacterium recently developed as a commercial larvicide that is used worldwide to control pestiferous and vector mosquitoes. Whereas B. sphaericus is highly active against larvae of Culex and Anopheles mosquitoes, it is virtually nontoxic to Aedes aegypti, an important vector species. In the present study, we evaluated the capacity of the cytolytic protein Cyt1A from Bacillus thuringiensis subsp. israelensis to enhance the toxicity of B. sphaericus toward A. aegypti. Various combinations of these two materials were evaluated, and all were highly toxic. A ratio of 10:1 of B. sphaericus to Cyt1A was 3, 600-fold more toxic to A. aegypti than B. sphaericus alone. Statistical analysis showed this high activity was due to synergism between the Cyt1A toxin and B. sphaericus. These results suggest that Cyt1A could be useful in expanding the host range of B. sphaericus.

Aedes↗
PubMed2000

Domain I plays an important role in the crystallization of Cry3A in Bacillus thuringiensis.

The insecticidal bacterium Bacillus thuringiensis synthesizes endotoxin Cry proteins of two size classes, 135 and 70 kDa, and both form crystalline inclusions in cells after synthesis. Crystallization of 135-kDa proteins is due to intermolecular attraction of regions in the C-terminal half of the molecule, and the N-terminal half fails to crystallize when synthesized in vivo. Alternatively, endotoxins of the 70-kDa class such as Cry2A and Cry3A, which correspond to the N-terminal half of 135-kDa molecules, crystallize readily after synthesis. Cry molecules of this size class consist of three principal domains, but the domains responsible for crystallization are not known. To identify these domains, chimeric proteins were constructed in which Cry3A Domains I or III, or I and III were substituted for the corresponding domains in truncated Cry1C molecules. Cry1C molecules with only Cry3A Domain III did not crystallize, whereas when Cry3A Domains I and III, or Domain I alone, were substituted, large inclusions were obtained. Except for the chimera consisting of Cry3A Domains I and III and Cry1C Domain II, most chimeras were not as stable as wild-type Cry3A or truncated Cry1C. These results show that Cry3A Domain I plays an important role in its crystallization in vivo.

Animals↗
PubMed2000

Cyt1A from Bacillus thuringiensis restores toxicity of Bacillus sphaericus against resistant Culex quinquefasciatus (Diptera: Culicidae).

The 2362 strain of Bacillus sphaericus, which produces a binary toxin highly active against Culex mosquitoes, has been developed recently as a commercial larvicide. It is being used currently in operational mosquito control programs in several countries including Brazil, France, India, and the United States. Laboratory studies have shown that mosquitoes can develop resistance to B. sphaericus, and low levels of resistance have already been reported in field populations in Brazil, France, and India. To develop tools for resistance management, the Cyt1A protein of Bacillus thuringiensis subsp. israelensis De Barjac was evaluated for its ability to suppress resistance to B. sphaericus in a highly resistant population of Culex quinquefasciatus Say. A combination of B. sphaericus 2362 in a 10:1 ratio with a strain of B. thuringiensis subsp. israelensis that only produces Cyt1A reduced resistance by >30,000-fold. Resistance was suppressed completely when B. sphaericus was combined with purified Cyt1A crystals in a 10:1 ratio. Synergism was observed between the Cyt1A toxin and B. sphaericus against the resistant mosquito population and accounted for the marked reduction in resistance. However, no synergism was observed between the toxins against a nonresistant mosquito population. These results indicate that Cyt1A could be useful for managing resistance to B. sphaericus 2362 in Culex populations, and also provide additional evidence that Cyt1A may synergize toxicity by enhancing the binding to and insertion of toxins into the mosquito microvillar membrane.

Animals↗
PubMed1999

Differential enhancement of Cry2A versus Cry11A yields in Bacillus thuringiensis by use of the cry3A STAB mRNA sequence.

Previously we demonstrated that the yield of Cry3A (70 kDa) can be increased as much as 10-fold when cry3A including its upstream STAB-SD mRNA stabilizing sequence is expressed in Bacillus thuringiensis under the control of cyt1A promoters. To determine whether the cyt1A promoters/STAB-SD combination (cyt1AP/STAB) has broader applicability, we used it to synthesize two other Cry endotoxins in the 70-kDa mass range, Cry2A and Cry11A. Combination of cyt1AP/STAB with orfs 2 and 3 of the cry2A operon yielded about 4. 4-fold the amount of Cry2A obtained with the wild-type cry2A operon. The yield of Cry11A obtained with a construct that contained the cyt1AP/STAB, cry11A and the 20-kDa protein gene was 1.3-fold the amount obtained with a construct similar to the wild-type operon. These results demonstrate that the cyt1AP/STAB combination can enhance synthesis of different Cry proteins significantly, but that the level of enhancement varies with the specific protein synthesized.

Animals↗
PubMed1999

A baculovirus anti-apoptosis gene homolog of the Trichoplusia ni granulovirus.

An inhibitor of apoptosis (iap) gene homolog (Tn-iap) of the Trichoplusia ni granulovirus (TnGV) was cloned, sequenced and mapped on the genome of TnGV. Tn-iap encoded a protein (Tn-IAP) of 301 amino acids with a predicted molecular mass of 35 kDa. The Tn-IAP contained the two sequence motifs, BIRs and RING finger, characteristic of IAP proteins, and shared identities of 21-27% and similarities of 28-53% with IAP proteins of Cydia pomonella GV (Cp-IAP), Orgyia pseudotsugata multinucleocapsid nucleopolyhedrovirus (MNPV) (Op-IAP1, 3), Autographa californica MNPV (Ac-IAP1), Bombyx mori NPV (Bm-IAP1), Lymantria dispar MNPV (Ld-IAP3) and Buzura suppressaria single nucleocapsid NPV (Bs-IAP1). However, Tn-IAP shared no significant homology with baculovirus IAP2 proteins. Using an antisense Tn-iap probe, two major transcripts of approximately 800 nt and 1600 nt were detected by Northern blot analysis of RNA extracted from the fat body of T. ni larvae infected with the TnGV. Unlike Cp-IAP and Op-IAP3, however, Tn-IAP did not rescue virion occlusion in SF21 cells infected with a p35-deficient AcMNPV mutant. Tn-IAP's synthesis in vivo but failure to rescue p35-deficient AcMNPV in SF21 cells suggests it is a functional IAP that is only effective in certain cell types.

Amino Acid Sequence↗
PubMed1998

Differential effects of helper proteins encoded by the cry2A and cry11A operons on the formation of Cry2A inclusions in Bacillus thuringiensis.

To compare the differential effects of cry2A operon orf2 (29-kDa protein gene) and Cry11A operon orf3 (20-kDa protein gene) on Cry2A synthesis and inclusion formation, we expressed the cry2A gene along with either the 29-kDa gene, 20-kDa gene, or both genes. Constructs containing 20-kDa, in the presence or absence of 29-kDa, produced more Cry2A than constructs which lacked this gene. Cry2A synthesis was also higher when the 29-kDa gene was included with 20-kDa in the construct. However, even in the presence of increased Cry2A synthesis facilitated by the 20-kDa gene, typical Cry2A crystals did not form if the 29-kDa gene was not included in the construct. These results suggest that the 29-kDa and 20-kDa proteins have different functions, with the 20-kDa protein acting like a molecular chaperone to enhance net Cry2A synthesis, and the 29-kDa protein likely serving as a template for the stabilization of Cry2A molecules and their organization into the rectangular inclusion characteristic of wild-type Cry2A crystals.

Bacillus thuringiensis↗
PubMed1998

Comparison of field-collected ascovirus isolates by DNA hybridization, host range, and histopathology.

Six field-collected ascovirus isolates obtained from five noctuid species in the continental United States were compared with respect to the general relatedness of their DNA, host range, and histopathology. Two isolates were from Spodoptera frugiperda, and the other four were from Autographa precationis, Heliothis virescens, Helicoverpa zea, and Trichoplusia ni. DNA-DNA hybridization studies showed that the six isolates belonged to three distinct viral species, with the isolates from S. frugiperda composing one species, those from A. precationis and H. virescens a second species, and those from H. zea and T. ni a third species. The host range and histopathology of each isolate was studied in eight noctuid species, S. frugiperda, Spodoptera ornithogalli, Spodoptera exigua, Spodoptera eridania, H. virescens, H. zea, A. precationis, and Feltia subterranea. Though some variation existed between the different isolates of each viral species, distinct patterns were apparent for each. The viral species from S. frugiperda had a host range that was limited primarily to Spodoptera species and both isolates of this virus only replicated and caused significant pathology in the fat body, whereas the viral species from A. precationis and H. virescens had a much broader host range that included most of the species tested, but also had a tissue tropism primarily restricted to the fat body. The viral species from T. ni and H. zea readily infected all the hosts tested, where the principal site of replication and significant pathology was the epidermis. In many test hosts, however, this viral species also replicated and caused significant pathology in the tracheal epithelium and to a lesser extent in the fat body. Aside from contributing to knowledge of ascovirus biology, these studies indicate that DNA hybridization profiles combined with studies of host range and tissue tropism can be used as characters for defining ascovirus species.

Animals↗
PubMed1998

Molecular characterization and expression of the Trichoplusia ni granulovirus helicase gene.

A putative DNA helicase gene from the granulovirus of Trichoplusia ni (TnGV) was cloned, sequenced, and compared with the corresponding gene of several multinucleocapsid nucleopolyhedroviruses (MNPVs) including those from Autographa californica (AcMNPV), Orgyia pseudotsugata (OpMNPV), Bombyx mori (BmNPV), and Spodoptera exigua (SeMNPV). The TnGV helicase gene (p137) encoded a helicase of 1158 amino acids with a predicted mass of 137 kDa. Comparison of p137 with AcMNPV p143 revealed 44.5% identity at the nucleotide level, and, respectively, 28.6% identity and 53.0% similarity at the amino acid level. Similar levels of identity and similarity were obtained when TnGV p137 was compared with the corresponding helicase genes of BmNPV, OpMNPV and SeMNPV. Using an antisense probe made from an internal 1.6 kb region of p137, a major transcript of approximately 3600 nt was detected by Northern blot analysis in fat body tissue from TnGV-infected larvae of T. ni. As both TnGV and AcMNPV replicate efficiently in larvae of T. ni, these results demonstrate that baculovirus putative DNA helicases which have diverged markedly can function efficiently in the same host. Three genes flanking TnGV p137, designated ORF68, ORF219 and ORF157, corresponded in order and orientation with AcMNPV ORFs 93, 94 and 96. However, the amino acid similarity between corresponding genes ranged from only 50.4 to 62.5%, providing further evidence that related baculovirus proteins which have diverged markedly can function efficiently in the same host.

Amino Acid Sequence↗