IE0 and IE1 are transactivator proteins of the most studied baculovirus, the Autographa californica multiple nucleopolyhedrovirus (AcMNPV). IE0 is a 72.6 kDa protein identical to IE1 with the exception of its 54 N-terminal amino acid... more
IE0 and IE1 are transactivator proteins of the most studied baculovirus, the Autographa californica multiple nucleopolyhedrovirus (AcMNPV). IE0 is a 72.6 kDa protein identical to IE1 with the exception of its 54 N-terminal amino acid residues. To gain some insight about important structural motifs of IE0, we expressed the protein and C‑terminal mutants of it under the control of the Drosophila heat shock promoter and studied the transactivation and replication functions of the transiently expressed proteins. IE0 was able to promote replication of a plasmid bearing the hr5 origin of replication of AcMNPV in transient transfections with a battery of eight plasmids expressing the AcMNPV genes dnapol, helicase, lef-1, lef-2, lef-3, p35, ie-2 and lef-7. IE0 transactivated expression of the baculovirus 39K promoter. Both functions of replication and transactivation were lost after introduction of selected mutations at the basic domain II and helix-loop-helix conserved structural motifs in...
Research Interests:
Research Interests:
Additional file 1: Figure S1. Amplification and sequencing strategy. Figure S2. MENA polymorphisms. Table S1. Primers for amplifying DWV strains. Table S2. Numerical details of the phylogenetic analyses. Table S3. SRA libraries and... more
Additional file 1: Figure S1. Amplification and sequencing strategy. Figure S2. MENA polymorphisms. Table S1. Primers for amplifying DWV strains. Table S2. Numerical details of the phylogenetic analyses. Table S3. SRA libraries and samples screened for DWV-D.
Research Interests:
The present project is aimed to improve the insecticidal potency of baculoviruses, to American and Israeli lepidopterous pests of Spodoptera and Heliothis species, by engineering recombinant baculoviruses expressing anti-insect toxins... more
The present project is aimed to improve the insecticidal potency of baculoviruses, to American and Israeli lepidopterous pests of Spodoptera and Heliothis species, by engineering recombinant baculoviruses expressing anti-insect toxins derived from scorpion venom. Through this study were isolated recombinant Autographa california M Nucleopolyhedroviruses (AcNPVs) which expressed alpha (LqhaIT), excitatory (AaIT, LqhIT1 and LqhIT3) and depressant (LqhIT2) anti-insect neurotoxins. Bioassays on Heliothis species (Helicoverpa armigera and Heliothis virescens) were employed to assess the potency of the viruses. The recombinant viruses possessed an enhanced speed of kill compared to wild type AcNPV. Recombinant AcNPVs expressing the depressant toxins emerged as appealing improved baculoviruses. Applied combinations of alpha, excitatory and depressant toxins enhanced their insecticidal activity against blowfly and lepidopterous larvae. Moreover, combined application of recombinant AcNPVs ex...
Research Interests:
Objectives: 1) Clarification of the mode of potentiation of an expressed insect selective neurotoxin (AaIT) by its recombinant baculovirus. 2) In vitro formation and/or modification of neuroactive polypeptides for the design of new... more
Objectives: 1) Clarification of the mode of potentiation of an expressed insect selective neurotoxin (AaIT) by its recombinant baculovirus. 2) In vitro formation and/or modification of neuroactive polypeptides for the design of new improved recombinant baculoviruses. Results: 1) A combined utilization of bioassays, LM-cytochemistry, the highly resolutive EM immunogold and electrical recording from the CNS of baculovirus and AaIT - expressing – recombinant baculovirus infected larvae it has been shown that the recombinant virus potentiates the effect of the toxin. Potentiation is achieved through its continuous expression in the infected tracheal epithelia thus providing a: a) Local supply of freshly produced toxin in the vicinity of its traget sites; b) Translocation of the expressed toxin to the insect CNS. The latter exposes the recombinant toxin to new, critical, target sites which are inaccessible through the natural route of scorpion envenomation. 2) Subjecting a recombinant Aa...
Research Interests:
Research Interests:
In 1977, a sample of diseased adult honeybees (Apis mellifera) from Egypt was found to contain large amounts of a previously unknown virus, Egypt bee virus, which was subsequently shown to be serologically related to deformed wing virus... more
In 1977, a sample of diseased adult honeybees (Apis mellifera) from Egypt was found to contain large amounts of a previously unknown virus, Egypt bee virus, which was subsequently shown to be serologically related to deformed wing virus (DWV). By sequencing the original isolate, we demonstrate that Egypt bee virus is in fact a fourth unique, major variant of DWV (DWV-D): more closely related to DWV-C than to either DWV-A or DWV-B. DWV-A and DWV-B are the most common DWV variants worldwide due to their close relationship and transmission by Varroa destructor. However, we could not find any trace of DWV-D in several hundred RNA sequencing libraries from a worldwide selection of honeybee, varroa and bumblebee samples. This means that DWV-D has either become extinct, been replaced by other DWV variants better adapted to varroa-mediated transmission, or persists only in a narrow geographic or host range, isolated from common bee and beekeeping trade routes.
Research Interests:
Many attempts to develop a reliable cell cultured-based system to study honey bee virus infections have encountered substantial difficulties. We investigated the ability of a cell line from a heterologous insect to sustain infection by a... more
Many attempts to develop a reliable cell cultured-based system to study honey bee virus infections have encountered substantial difficulties. We investigated the ability of a cell line from a heterologous insect to sustain infection by a honey bee virus. For this purpose, we infected the Lepidopteran hemocytic cell line (P1) with Deformed wing virus (DWV). The genomic copies of DWV increased upon infection, as monitored by quantitative RT-PCR. Moreover, a tagged-primer-based RT-PCR analysis showed the presence of DWV negative-sense RNA in the cells, indicating virus replication. However, the DWV from infected cells was mildly infectious to P1 cells. Similar results were obtained when the virus was injected into Apis mellifera pupae. Thus, though the virus yields from the infected cells appeared to be very low, we show for the first time that DWV can replicate in a heterologous cell line. Given the availability of many other insect cell lines, our study paves the way for future explo...
Research Interests:
In the past centuries, viruses have benefited from globalization to spread across the globe, infecting new host species and populations. A growing number of viruses have been documented in the western honey bee, Apis mellifera. Several of... more
In the past centuries, viruses have benefited from globalization to spread across the globe, infecting new host species and populations. A growing number of viruses have been documented in the western honey bee, Apis mellifera. Several of these contribute significantly to honey bee colony losses. This review synthetizes the knowledge of the diversity and distribution of honey-bee-infecting viruses, including recent data from high-throughput sequencing (HTS). After presenting the diversity of viruses and their corresponding symptoms, we surveyed the scientific literature for the prevalence of these pathogens across the globe. The geographical distribution shows that the most prevalent viruses (deformed wing virus, sacbrood virus, black queen cell virus and acute paralysis complex) are also the most widely distributed. We discuss the ecological drivers that influence the distribution of these pathogens in worldwide honey bee populations. Besides the natural transmission routes and the...
Research Interests:
Virus host shifts occur frequently, but the whole range of host species and the actual transmission pathways are often poorly understood. Deformed wing virus (DWV), an RNA virus described from honeybees (Apis mellifera), has been shown to... more
Virus host shifts occur frequently, but the whole range of host species and the actual transmission pathways are often poorly understood. Deformed wing virus (DWV), an RNA virus described from honeybees (Apis mellifera), has been shown to have a broad host range. Since ants are often scavenging on dead honeybees, foodborne transmission of these viruses may occur. However, the role of the ant Myrmica rubra as an alternative host is not known and foodborne transmission to ants has not been experimentally addressed yet. Here, we show with a 16-week feeding experiment that foodborne transmission enables DWV type-A and -B to infect M. rubra and that these ants may serve as a virus reservoir. However, the titers of both plus- and minus-sense viral RNA strands decreased over time. Since the ants were fed with highly virus-saturated honeybee pupae, this probably resulted in initial viral peaks, then approaching lower equilibrium titers in infected individuals later. Since DWV infections wer...
Research Interests:
Varroa destructor is an ectoparasitic mite of Asian or Eastern honeybees Apis cerana (A. cerana) which has become a serious threat to European subspecies of Western honeybees Apis mellifera (A. mellifera) within the last century. V.... more
Varroa destructor is an ectoparasitic mite of Asian or Eastern honeybees Apis cerana (A. cerana) which has become a serious threat to European subspecies of Western honeybees Apis mellifera (A. mellifera) within the last century. V. destructor and its vectored honeybee viruses became serious threats for colony survival. This is a short period for pathogen- and host-populations to adapt. To look for possible variation in the composition of viral populations we performed RNA metagenomic analysis of the Western honeybee subspecies A. m. ligustica, A. m. syriaca, A. m. intermissa, and A. cerana and their respective V. destructor mites. The analysis revealed two novel viruses: Varroa orthomyxovirus-1 (VOV-1) in A. mellifera and V. destructor and a Hubei like-virga virus-14 homolog in V. destructor. VOV-1 was more prevalent in V. destructor than in A. mellifera and we found evidence for viral replication in both hosts. Interestingly, we found differences in viral loads of A. cerana and th...
Research Interests: Biology, Agriculture, Medicine, Viruses, Honey bee, and 4 moreSubspecies, Varroa, Apis cerana, and Varroa destructor
Enveloped virions penetrate eukaryotic cells by two alternative routes (Chop-pin and Scheid, 1980; White et al., 1983). Envelopes of viruses belonging to the paramyxovirus group fuse with cells’ plasma membranes at pH 7.4 and consequently... more
Enveloped virions penetrate eukaryotic cells by two alternative routes (Chop-pin and Scheid, 1980; White et al., 1983). Envelopes of viruses belonging to the paramyxovirus group fuse with cells’ plasma membranes at pH 7.4 and consequently microinject their content, the viral nucleocapsid, directly into the cell cytoplasm (Choppin and Scheid, 1980; Loyter and Volsky, 1982; White et al., 1983). A different way of entry has been described for most other enveloped virions such as those belonging to the orthomyxovirus, toga, rhabdo, and herpes groups. Such viruses are taken into cells by endocyticlike processes. Fusion of the viral envelopes with the endosomal or lysosomal membranes is triggered by the intraorganelle low-pH environment and leads to the introduction of the viral content into the intracellular space (Chopin and Scheid, 1980; White et al., 1983). Fusion of the pH-dependent virions with the plasma membrane can be triggered by lowering the pH of the medium containing the virus-associated cells.
Research Interests:
Research Interests:
Research Interests: Biology, Virology, Medicine, Animals, Neurotoxins, and 15 moreRecombinant DNA, Molecular cloning, Genetically Modified, Larva, Diptera, Insect, Moths, Base Sequence, Recombinant Proteins, Spodoptera littoralis, Biochemistry and cell biology, Helicoverpa armigera, Spodoptera litura, Molecular Sequence Data, and Nucleopolyhedrovirus
Public concern over the risks associated with widespread use of insecticidal chemicals has motivated our efforts to develop safer and more effective approaches to pest control. Thus, natural insecticidal compounds derived from venomous... more
Public concern over the risks associated with widespread use of insecticidal chemicals has motivated our efforts to develop safer and more effective approaches to pest control. Thus, natural insecticidal compounds derived from venomous animals may serve as rational alternatives. Venoms of arthropods such as scorpions, spiders, braconid and sphecid wasps, reduviid bugs and centipedes (Zlotkin, 1985) which prey on insects, possess anti-insect selective polypeptidic neurotoxins. Such toxins have already shown promise when incorporated into insect pathogens by enhancing their killing efficacy (Chejanovsky et al., 1995; Maeda et al., 1991; Stewart et al., 1991; Tomalski and Miller, 1991). These toxins bind to insect sodium channels (Gordon et al., 1992), modify their properties and disrupt normal neuromuscular functions leading to paralysis and death. Thus, the incorporation of anti-insect selective scorpion toxins into insecticidal microorganisms offers an opportunity to improve and augment current crop protection strategies (Maeda et al., 1991; Stewart et al., 1991; Tomalski and Miller, 1991). In order to minimize biological hazards which may be associated with such a genetic approach and to avoid the possibility of resistance build-up of insect pests, the molecular basis for anti-insect selectivity of these toxins should be clarified. Furthermore, usage of insecticidal toxins should be limited to those revealing the ‘animal group specificity’ phenomenon where a toxin shows activity against a given group of organisms and is not effective against other groups of organisms. In cases where a venomous organism feeds on a given limited group of animals, the ‘animal group specificity’ is manifested already on the level of the whole venom.
Research Interests:
The extensive use or non-specific, hazardous, chemical insecticides demands the development of "healthier" alternative means for pest control. Insect-specific, baculoviruses expressing anti-insect toxin genes (from mites or... more
The extensive use or non-specific, hazardous, chemical insecticides demands the development of "healthier" alternative means for pest control. Insect-specific, baculoviruses expressing anti-insect toxin genes (from mites or scorpions) demonstrated in laboratory assays and field trials enhanced insecticidal activity and provided some protection from lepidopterous larvae to agricultural plantations. To utilize recombinant baculoviruses as commercial biopesticides in row crop agriculture, further increase in their speed of kill should be achieved and the reduction in crop damage should be comparable to the levels obtained with organic insecticides (the problem). In this project we developed strategies to improve further the efficacy of recombinant baculoviruses which included: I) Synergism among baculoviruses expressing different anti-insect toxins: a) Synergism among two complementary anti-insect scorpion neurotoxins each expressed by a separate recombinant baculovirus, both...
Honey bee viruses have gained substantial attention due to their involvement in the collapse of honey bee colonies. This chapter focuses on honey bee viruses linked to honey bee colony losses, specifically those that cause paralysis,... more
Honey bee viruses have gained substantial attention due to their involvement in the collapse of honey bee colonies. This chapter focuses on honey bee viruses linked to honey bee colony losses, specifically those that cause paralysis, those carried by Varroa mites, and those that cause deformed wings. Often virus infections in the colony are dormant and asymptomatic. Asymptomatic infections can convert to active (and visible) symptomatic infections when colonies are exposed to various stresses. These stresses include biological, such as Varroa destructor, mechanical, such as the utilization of bee colonies for pollination in net-covered crops, and chemical, such as the use of insecticides harmful to bees. These stresses enable viruses to overcome natural honey bee defenses, by facilitating viral access to the bee blood (hemolymph) and by weakening its immune system. Knowledge and understanding of the cause-and-effect interactions between viruses, stress factors, and honey bees will p...
Research Interests:
Honey bee (Apis mellifera) has a thousand years of history in this part of Asia. The native honey bee race is considered to be A. mellifera syriaca. This subspecies was generally replaced by a more docile subspecies A. mellifera... more
Honey bee (Apis mellifera) has a thousand years of history in this part of Asia. The native honey bee race is considered to be A. mellifera syriaca. This subspecies was generally replaced by a more docile subspecies A. mellifera ligustica, but members of other subspecies are also occasionally introduced. Only about parts of the country area are suitable for honey bees due to very limited vegetation arid conditions in the southern part of the country. The majority of the colonies are concentrated at the center and north of the country reaching density of more than 14 colonies per square kilometers. To supplement bee forage, Eucalyptus trees are planted intensively around the country. Local beekeepers practice modern methods of beekeeping using Langstroth hive boxes. All professional beekeepers usually treat their colonies preventively against Varroa destructor mites and foulbrood diseases. Many beekeepers also treat preventively against Nosema disease. Despite regular management, Var...
Research Interests:
With a growing number of parasites and pathogens experiencing large-scale range expansions, monitoring diversity in immune genes of host populations has never been so important because it can inform on the adaptive potential to resist the... more
With a growing number of parasites and pathogens experiencing large-scale range expansions, monitoring diversity in immune genes of host populations has never been so important because it can inform on the adaptive potential to resist the invaders. Population surveys of immune genes are becoming common in many organisms, yet they are missing in the honey bee (Apis mellifera L.), a key managed pollinator species that has been severely affected by biological invasions. To fill the gap, here we identified single nucleotide polymorphisms (SNPs) in a wide range of honey bee immune genes and developed a medium-density assay targeting a subset of these genes. Using a discovery panel of 123 whole-genomes, representing seven A. mellifera subspecies and three evolutionary lineages, 180 immune genes were scanned for SNPs in exons, introns (< 4 bp from exons), 3’ and 5´UTR, and < 1 kb upstream of the transcription start site. After application of multiple filtering criteria and validation...
Research Interests:
Nosema ceranae is a hot topic in honey bee health as reflected by numerous papers published every year. This review presents an update of the knowledge generated in the last 12 years in the field of N. ceranae research, addressing the... more
Nosema ceranae is a hot topic in honey bee health as reflected by numerous papers published every year. This review presents an update of the knowledge generated in the last 12 years in the field of N. ceranae research, addressing the routes of transmission, population structure and genetic diversity. This includes description of how the infection modifies the honey bee's metabolism, the immune response and other vital functions. The effects on individual honey bees will have a direct impact on the colony by leading to losses in the adult's population. The absence of clear clinical signs could keep the infection unnoticed by the beekeeper for long periods. The influence of the environmental conditions, beekeeping practices, bee genetics and the interaction with pesticides and other pathogens will have a direct influence on the prognosis of the disease. This review is approached from the point of view of the Mediterranean countries where the professional beekeeping has a high...
Research Interests:
Research Interests:
Bees are important plant pollinators in agricultural and natural ecosystems. High average annual losses of honey bee (Apis mellifera) colonies in some parts of the world, and regional population declines of some mining bee species... more
Bees are important plant pollinators in agricultural and natural ecosystems. High average annual losses of honey bee (Apis mellifera) colonies in some parts of the world, and regional population declines of some mining bee species (Andrena spp.), are attributed to multiple factors including habitat loss, lack of quality forage, insecticide exposure, and pathogens, including viruses. While research has primarily focused on viruses in honey bees, many of these viruses have a broad host range. It is therefore important to apply a community level approach in studying the epidemiology of bee viruses. We utilized high-throughput sequencing to evaluate viral diversity and viral sharing in sympatric, co-foraging bees in the context of habitat type. Variants of four common viruses (i.e., black queen cell virus, deformed wing virus, Lake Sinai virus 2, and Lake Sinai virus NE) were identified in honey bee and mining bee samples, and the high degree of nucleotide identity in the virus consensu...
Research Interests:
The sudden collapse of honey bee colonies in California in 2005 and alarming reports about significant colony losses in the U [...]
Research Interests:
Spodoptera frugiperda SF9 cells infected with mutants of the Autographa californica nucleopolyhedrovirus (AcMNPV) which lack a functional p35 gene undergo apoptosis, aborting the viral infection. The Spodoptera littoralis... more
Spodoptera frugiperda SF9 cells infected with mutants of the Autographa californica nucleopolyhedrovirus (AcMNPV) which lack a functional p35 gene undergo apoptosis, aborting the viral infection. The Spodoptera littoralis nucleopolyhedrovirus (SlNPV) was able to suppress apoptosis triggered by vΔP35K/pol+, an AcMNPVp35 null mutant. To identify the putative apoptotic suppressor gene of SlNPV, overlapping cosmid clones representing the entire SlNPV genome were individually cotransfected along with genomic DNA of vΔP35K/pol+. Using this complementation assay, we isolated a SlNPV DNA fragment that was able to rescue the vΔP35K/pol+ infection in SF9 cells. By further subcloning and rescue, we identified a novel SlNPV gene, Slp49. TheSlp49 sequence predicted a 49-kDa polypeptide with about 48.8% identity to the AcMNPV apoptotic suppressor P35. SLP49 displays a potential recognition site, TVTDG, for cleavage by death caspases. Recombinant AcMNPVs deficient inp35 bearing the Slp49 gene did ...
Research Interests:
Multiple infections are common in honey bees, Apis mellifera, but the possible role of nutrition in this regard is poorly understood. Microsporidian infections, which are promoted by protein-fed, can negatively correlate with virus... more
Multiple infections are common in honey bees, Apis mellifera, but the possible role of nutrition in this regard is poorly understood. Microsporidian infections, which are promoted by protein-fed, can negatively correlate with virus infections, but the role of protein nutrition for the microsporidian-virus interface is unknown. Here, we challenged naturally deformed wing virus - B (DWV-B) infected adult honey bee workers fed with or without pollen ( = protein) in hoarding cages, with the microsporidian Nosema ceranae. Bee mortality was recorded for 14 days and N. ceranae spore loads and DWV-B titers were quantified. Amongst the groups inoculated with N. ceranae, more spores were counted in protein-fed bees. However, N. ceranae infected bees without protein-diet had reduced longevity compared to all other groups. N. ceranae infection had no effect on protein-fed bee's longevity, whereas bees supplied only with sugar-water showed reduced survival. Our data also support that protein...
The viral ecology of bee communities is complex, where viruses are readily shared among co-foraging bee species. Additionally, in honey bees (), many viruses are transmitted - and their impacts exacerbated - by the parasiticmite. Thus... more
The viral ecology of bee communities is complex, where viruses are readily shared among co-foraging bee species. Additionally, in honey bees (), many viruses are transmitted - and their impacts exacerbated - by the parasiticmite. Thus far, the viruses found to be shared across bee species and transmitted bymites are positive-sense single-stranded RNA viruses. Recently, a negative-sense RNA enveloped virus, Apis rhabdovirus-1 (ARV-1), was found inhoney bees in Africa, Europe, and islands in the Pacific. Here, we describe the identification - using a metagenomics approach - of ARV-1 in two bee species (and) and inmites from populations collected in the United States and Israel. We confirmed the presence of ARV-1 in pools of,, andfrom Israeli and U.S. populations by RT-PCR and found that it can reach high titers in individual honey bees and mites (10-10viral genomic copies per individual). To estimate the prevalence of ARV-1 in honey bee populations, we screened 104 honey bee colonies ...
Varroa destructor infestation of Apis mellifera colonies carries and/or promotes replication of honey bee viruses like the Deformed wing virus, the Varroa destructor virus-1, the Acute bee paralysis virus, the Israeli acute bee paralysis... more
Varroa destructor infestation of Apis mellifera colonies carries and/or promotes replication of honey bee viruses like the Deformed wing virus, the Varroa destructor virus-1, the Acute bee paralysis virus, the Israeli acute bee paralysis virus and the Kashmir bee virus that have been well described and characterized; but viruses exclusively associated with Varroa were not found. To look for viruses that may associate with- or infect V. destructor we performed deep sequencing (RNA-seq) of RNA extracted from honey bees and mites in Varroa-infested untreated colonies. Comparative bioinformatic analysis of the two separate contig-assemblies generated from the sequences' reads annotated using Blastx enabled identification of new viruses unique to Varroa and absent in A. mellifera: an Iflavirus and a virus with homology to Ixodes scapularis associated virus 2, that we named Varroa destructor virus 2 (VDV-2) and 3(VDV-3), respectively. We validated these findings sequencing the mite- a...
Research Interests:
Research Interests:
Research Interests:
Baculoviruses possess two types of genes that suppressed apoptosis, p35 and inhibitor of apoptosis (iap). In this study we report the isolation and identification of an inhibitor of apoptosis gene Sliap in the genome of the Spodoptera... more
Baculoviruses possess two types of genes that suppressed apoptosis, p35 and inhibitor of apoptosis (iap). In this study we report the isolation and identification of an inhibitor of apoptosis gene Sliap in the genome of the Spodoptera littoralis nucleopolyhedrovirus (SINPV). The Sliap sequence predicted a 15 kDa polypeptide with only one BIR domain and a RING finger, both motifs characteristic of the IAP family of proteins, and a third specific acidic-rich motif. These characteristics, shared with the Spodoptera littura NPV IAP2/3, Epiphyas postvittana NPV IAP4, Lymantria dispar NPV IAP and Orgyia pseudotsugata NPV IAP4 (Orf 107) allowed us to classify them in a new homology group (IAP-4). Sliap was able to delay, but not to suppress, apoptosis induced by replication of a recombinant AcMNPV deficient in p35. In SINPV infected-SF9 cells Sliap was expressed earlier than sl-p49 suggesting that its role at the initiation of infection was to delay the apoptotic response of the host.
Research Interests:
Research Interests:
Research Interests:
A country-wide screen for viral pathogens in Israeli apiaries revealed significant incidence of deformed wing virus (DWV) and Varroa destructor-1 virus (VDV-1). To understand these viruses&amp;amp;amp;amp;amp;amp;#39; possible... more
A country-wide screen for viral pathogens in Israeli apiaries revealed significant incidence of deformed wing virus (DWV) and Varroa destructor-1 virus (VDV-1). To understand these viruses&amp;amp;amp;amp;amp;amp;#39; possible involvement in deformed wing syndrome of honey bees, we studied their replication in symptomatically and asymptomatically infected bees qualitatively and quantitatively, using RT-PCR, quantitative real-time RT-PCR, and immunodetection of the major viral capsid protein VP1. We found, for the first time, replication of VDV-1 and/or a VDV-1-DWV recombinant virus in the heads of recently emerged symptomatic bees. These viruses replicated to high copy numbers, yielding the major viral capsid VP1 processed for subsequent assembly of viral particles. Our results clearly distinguished between symptomatic and asymptomatic bees infected with VDV-1 and VDV-1-DWV and suggest the hypothesis that VDV-1, in addition to DWV, may be involved in inducing the deformed wing pathology. Thus VDV-1-DWV recombination may yield virulent strains able to cause overt infections in Varroa-infested bee colonies.
Research Interests:
Ethylene-inducing xylanase (EIX) elicits plant defense responses in certain tobacco (Nicotiana tabacum) and tomato cultivars in addition to its xylan degradation activity. It is not clear, however, whether elicitation occurs by cell wall... more
Ethylene-inducing xylanase (EIX) elicits plant defense responses in certain tobacco (Nicotiana tabacum) and tomato cultivars in addition to its xylan degradation activity. It is not clear, however, whether elicitation occurs by cell wall fragments released by the enzymatic activity or by the xylanase protein interacting directly with the plant cells. We cloned the gene encoding EIX protein and overexpressed it in insect cells. To determine the relationship between the two activities, substitution of amino acids in the xylanase active site was performed. Substitution at glutamic acid-86 or -177 with glutamine (Gln), aspartic acid (Asp), or glycine (Gly) inhibited the β-1-4-endoxylanase activity. Mutants having Asp-86 or Gln-177 also lost the ability to induce the hypersensitive response and ethylene biosynthesis. However, mutants having Gln-86, Gly-86, Asp-177, or Gly-177 retained ability to induce ethylene biosynthesis and the hypersensitive response. Our data show that the xylanase...
Research Interests: Gene expression, Lepidoptera, Biological Sciences, Plant, PLANT DEFENSE, and 15 moreNicotiana Tabacum, Active site, Glutamine, Elicitation, Amino Acid Profile, Amino Acid Sequence, Base Sequence, Cell Wall, Amino Acid Substitution Rates, Hypersensitive Response, Enzymatic Activity, Glutamic Acid, Lycopersicon esculentum, Plant Leaves, and Molecular Sequence Data
Potyviruses, as typical non-persistently transmitted viruses, are carried within the stylets of aphids. Cuticle proteins (CuPs), which are a major component of the insect cuticle, were examined forin vitrobinding to the potyviral helper... more
Potyviruses, as typical non-persistently transmitted viruses, are carried within the stylets of aphids. Cuticle proteins (CuPs), which are a major component of the insect cuticle, were examined forin vitrobinding to the potyviral helper component–proteinase (HC–Pro). Proteins in 8 M urea extracts fromMyzus persicaewere separated by SDS-PAGE, electroblotted onto membranes and identified as CuPs by using specific antibodies toM. persicaeCuP. BlottedM. persicaeprotein extracts were overlaid with two HC–Pros, differing by the presence of K or E in the KLSC domain. The HC–Pro with KLSC, known to assist transmission, was found to bindM. persicaeproteins, whereas the HC–Pro with ELSC, being deficient in assisting transmission, did not. To identify CuPs that react with HC–Pro, protein extracts were separated by two-dimensional gel electrophoresis. Nine proteins reacting with HC–Pro were sequenced by mass spectrometry. Sequences of peptides in four proteins, of molecular masses between 22 an...
Research Interests:
Baculoviruses are orally infectious to insects and considered to be natural insecticides. To enhance their speed-of-kill these viruses were engineered to express arthropod neurotoxins under the control of various strong promoters.... more
Baculoviruses are orally infectious to insects and considered to be natural insecticides. To enhance their speed-of-kill these viruses were engineered to express arthropod neurotoxins under the control of various strong promoters. Although this strategy proved to be efficient, it raised recently concerns about safety. We analyzed the speed-of-kill and safety of Autographa californica multiple nucleopolyhedrovirus expressing the insecticidal scorpion neurotoxin AaIT and found that the mortality of Helicoverpa armigera larvae was enhanced significantly when the expression was controlled by the baculovirus delayed-early promoter 39K rather than the very late promoter p10. This improvement was also reflected in better protection of cotton leaves on which these insects were fed. Using lacZ as a sensitive reporter we also found that expression driven by the 39K promoter was detected in insect but not in mammalian cells. These results imply that by selection of an appropriate viral promoter, engineered baculoviruses may comply with the high standard biosafety requirements from a genetically modified organism (GMO). Our results provide further support for the potential use of engineered baculoviruses in insect pest control in a safely manner.
Research Interests:
A cDNA library for Myzus persicae has served to identify sequences coding for cuticular proteins (CPs) with RR-1 and RR-2 consensus. Two putative CPs showed a common RR-2 chitin binding domain (CBD) but differed in their C and N... more
A cDNA library for Myzus persicae has served to identify sequences coding for cuticular proteins (CPs) with RR-1 and RR-2 consensus. Two putative CPs showed a common RR-2 chitin binding domain (CBD) but differed in their C and N terminals. Two other predicted CPs showed a typical RR-1 CBD but differed in size and sequence of the C and N terminals. An additional sequence encoding for a protein that showed terminal amino acid repeats similar to those of putative CPs from M. persicae, but lacked the R &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp; R consensus, was also described. A comparison of the sequences obtained from the cDNA library with those attained from the genomic DNA, confirmed their identity as cuticular proteins genes. Presence of introns was revealed in the Mpcp4 and Mpcp5 genes coding for CPs with an RR-1 consensus. The Mpcp4 has a single large intron, while the Mpcp5 has two shorter ones. Introns were not found in the Mpcp2 and Mpcp3 genes encoding for CPs with RR-2 consensus. Differences were also noticed for 3&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; UTR and 5&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; UTR of both the RR-1 and RR-2 CPs. CPs genes were expressed in bacteria, and the resulting protein was identified as a CP by amino acid sequencing.
Research Interests: Physiology, Sequence alignment, Animals, Aphids, Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis, and 14 moreIntrons, Molecular cloning, Myzus persicae, Genomic DNA, Molecular weight, Protein isoforms, Amino Acid Sequence, Base Sequence, Recombinant Proteins, cDNA library, Biochemistry and cell biology, Aphid, Molecular Sequence Data, and conserved sequence
Research Interests:
Research Interests:
Research Interests:
Apoptosis is a physiological program of cell suicide conserved in invertebrates and vertebrates. Apoptosis is crucial to the normal development of organisms and in tissue homeostasis, by promoting elimination of unwanted cells including... more
Apoptosis is a physiological program of cell suicide conserved in invertebrates and vertebrates. Apoptosis is crucial to the normal development of organisms and in tissue homeostasis, by promoting elimination of unwanted cells including damaged- or virus-infected cells. Because of the importance of programmed cell death for the survival of the organism a tight regulation is exerted at various activation levels of the cell-death machinery. The utilization of the baculovirus Autographa californica multiple nucleopolyhedrovirus to identify genes that inhibit the apoptotic process will be described using a transfection-based approach, illustrated by identification of the p49 gene.
Research Interests:
Research Interests:
Abstract To evaluate symptoms, extent, and possible causes of colony decline and losses in Israel, we carried out (1) a survey of honeybee colony losses and potential causes via mail and phone;(2) systematic sampling of healthy and... more
Abstract To evaluate symptoms, extent, and possible causes of colony decline and losses in Israel, we carried out (1) a survey of honeybee colony losses and potential causes via mail and phone;(2) systematic sampling of healthy and problematic beehives after requeening ...