Biomedical subjects

Johannes A Jehle

Publications and source records attributed to Johannes A Jehle.

15 recordsLinked to original sources

PubMed2025

Amplicon-based analyses of single-nucleotide polymorphisms reveal the genetic structure of a forest insect baculovirus.

Amplicon-based next-generation sequencing (aNGS) is a powerful tool in diagnostics and genetic studies. We developed an aNGS approach to study the population structure of the Lymantria dispar multiple nucleopolyhedrovirus (LdMNPV), a specific pathogen of the spongy moth Lymantria dispar, a devastating lepidopteran pest in European, Asian, and American deciduous forests. Naturally occurring pathogens, such as LdMNPV, are frequently reported to cause epizootics and a rapid decline of insect pest populations. DNA samples of pooled LdMNPV-infected larvae from forest regions in Northern Bavaria (Germany) were subjected to whole genome sequencing (WGS) and aNGS optimization. Then, five marker regions were identified in the genome of LdMNPV for PCR amplification, covering 21 highly specific single-nucleotide polymorphism (SNP) positions that enabled comprehensive analysis at the intra- and intersample levels. These markers were used in aNGS analyses of 70 single larvae collected in 12 forest sites, followed by SNP-based hierarchical clustering on principal components (HCPC). This approach identified three LdMNPV population clusters consisting of homogenous (pure) and heterogeneous (mixed) LdMNPV samples. To explain the genetic variability within each sample, a model based on linear optimization was developed and validated by comparing the predictions from aNGS and WGS data. The analyses showed that LdMNPV from Bavarian forests carried genetic variants highly similar to those present in the commercial product Gypchek®, developed for biocontrol. The distribution of genetic characteristics showed some trends of geographic and temporal prevalence, which are indicative of short-distance and long-distance transmission. The aNGS approach offers a fast, cost-effective, and comprehensive insight into the natural population structure of LdMNPV.

insects↗

PubMed2006

Field resistance of codling moth against Cydia pomonella granulovirus (CpGV) is autosomal and incompletely dominant inherited.

The current appearance of local codling moth populations with resistance to Cydia pomonella granulovirus (CpGV) is an impediment to continuous CpGV application. Therefore, crossing experiments have been performed in order to gain information about the inheritance of resistance. Evidence is presented that the observed field resistance is stably inherited even under non-selective conditions in the laboratory. Offspring of reciprocal F(1) crosses between a susceptible ('S') and a resistant ('R') strain and backcrosses between F(1) and S were bioassayed at different CpGV concentrations. The resistant strain showed 100 times lower susceptibility in 7-day bioassays. The responses of the reciprocal crosses (male S x female R and female S x male R) did not differ significantly, indicating that resistance is autosomally inherited. The median lethal concentration for the F(1) progeny was intermediate between those of its parental strains. Mortality data obtained from the backcrosses suggested that inheritance of resistance is due to a non-additive, polygenic trait.

Animals↗

PubMed2006

Sequence analysis and quantification of transposase cDNAs of transposon TCp3.2 in Cydia pomonella larvae.

The Tc1-like transposable element TCp3.2 was previously found to be horizontally transferred from the genome of Cydia pomonella to the C. pomonella granulovirus (CpGV). In this study, the transcription of transposase genes of endogenous TCp3.2 copies in the insect host genome was investigated. Cloning and sequencing of cDNAs prepared from TCp3.2 transposase transcripts resulted in the identification of a 199-bp-long intron. Sequence heterogeneities among different cDNA clones suggested that multiple copies of the transposase are transcribed, but that a part of these copies encode a defective transposase. The actin gene of C. pomonella was cloned and sequenced, and used to standardise quantitative real time PCR on prepared cDNA of the TCp3.2 transposase. Comparison of cDNA levels of TCp3.2 transposase prepared from mock and CpGV-infected C. pomonella larvae did not provide evidence that CpGV infection influenced the transcription level of TCp3.2 transposase.

Amino Acid Sequence↗

PubMed2005

Molecular identification and phylogenetic analysis of baculoviruses from Lepidoptera.

PCR amplification of the highly conserved baculovirus genes late expression factor 8 (lef-8), late expression factor 9 (lef-9) and polyhedrin/granulin (polh/gran) combined with molecular phylogenetic analyses provide a powerful tool to identify lepidopteran-specific baculoviruses and to study their diversity. In the present investigation, we have improved the degenerate oligonucleotides and corroborated the approach that was recently described by Lange et al. (Lange, M., Wang, H., Zhihong, H., Jehle, J.A., 2004. Towards a molecular identification and classification system of lepidopteran-specific baculoviruses. Virology 325, 36-47.). Baculovirus DNA was isolated from 71 uncharacterized historic baculovirus samples, and partial gene sequences were amplified by using gene-specific degenerate PCR primers. The obtained PCR products were directly sequenced, and the deduced amino acid sequences were compiled and aligned with published sequences of these target genes. A phylogenetic tree of 117 baculoviruses was inferred using maximum parsimony and distance methods. Based on the comprehensive phylogenetic analysis of the partial lef-8, lef-9 and polh/gran genes, we propose a phylogenetic species criterion for lepidopteran-specific baculoviruses that uses the genetic distances of these genes for species demarcation.

Animals↗

PubMed2005

In vitro plant regeneration from leaves and internode sections of sweet cherry cultivars (Prunus avium L.).

Regeneration of adventitious shoots from leaves and, for the first time, from internode sections were compared and optimized for five economically important sweet cherry cultivars, i.e. "Schneiders", "Sweetheart", "Starking Hardy Giant", "Kordia" and "Regina" (Prunus avium L.). The influence of basal media, carbon source, combination and dosage of phytohormones, ethylene inhibitor such as silver thiosulfate and a 16 h:8 h light:dark photoperiod versus complete darkness were evaluated. Both, DKW/WPM (1:1) and Quoirin/Lepoivre (QL) basal media stimulated organogenesis more than QL/WPM (1:1), Chee and Pool (CP), Murashige Skoog (MS), Driver and Kuniyuki (DKW) or woody plant (WPM) media did. An induction phase in darkness resulted in lower or zero regeneration rates. The best regeneration efficiencies were generally obtained with thidiazuron in combination with indole-3-butyric-acid. The addition of silver thiosulfate resulted in a similar or reduced regeneration efficiency. Significant genotypic variability in adventitious bud formation was evident for both explant sources, leaf and internode section. Adventitious shoots were obtained from 11% of leaf explants and 50% of internode sections indicating that shoot regeneration from internodes was significantly more efficient than from leaves.

Plant Leaves↗

PubMed2005

Biological and molecular characterization of a multicapsid nucleopolyhedrovirus from Thysanoplusia orichalcea (L.) (Lepidoptera: Noctuidae).

A multicapsid nucleopolyhedrovirus (ThorMNPV) that was co-isolated with a single nucleocapid ThorSNPV from mixed infected larvae of Thysanoplusia orichalcea L. (Lepidoptea: Noctuidae) is characterized. Scanning electron microscopy of ThorMNPV showed a dodecahedral-shaped occlusion body (OB). The occluded virions contained one to as many as eight nucleocapsids/virion. Virion band profiles in gradient centrifugation were consistent in at least 10 rounds of centrifugation from different virion sample preparations. The ThorMNPV had high virulence to third instar Trichoplusia ni and Pseudoplusia includens with LD50 values of 17 and 242OBs per larva, respectively. However, ThorMNPV did not cause mortality in Spodoptera exigua, Spodoptera frugiperda, Spodoptera eridania, Anticarsia gemmatalis, and Helicoverpa zea. ThorMNPV replicates in cells of various tissues such as the fat body and tracheal epithelium cells. T. ni High 5 cells were permissive to ThorMNPV in terms of infection and viral DNA transfection, but SF-21 was less permissive and the infection process was slower. Production of OBs by ThorMNPV in the nuclei of SF-21 was not well pronounced. The genome size of ThorMNPV was estimated to be 136 kb. The polyhedrin gene open reading frame (ORF) was cloned and completely sequenced. The promoter sequence is identical to that of Autographa californica MNPV. Phylogenetic analyses using partial sequences of the polh, lef-8, and lef-9 revealed that ThorMNPV is a member of the Group I NPVs and is related but distinct from the AcMNPV/Rachiplusia ou NPV/Bombyx mori NPV cluster.

Amino Acid Sequence↗

PubMed2005

Virulence and competitiveness of Cydia pomonella granulovirus mutants: parameters that do not match.

The LD50, median survival time (ST50) and virus production are virulence parameters that are commonly used to describe the biological characteristics of viruses. In this study, these parameters were determined for Cydia pomonella granulovirus (CpGV-M) and two naturally occurring mutants (CpGV-MCp4 and -MCp5) that carry Tc1-like insect transposable elements. The three virus genotypes were similar in their LD50, ST50 and virus production. However, the mutant genotypes MCp4 and MCp5 were very effectively out-competed by CpGV-M in direct competition experiments, where Cydia pomonella larvae were co-infected with known ratios of occlusion bodies or budded virus of CpGV-M and one of the two mutants. It was demonstrated that MCp5 and MCp4 could not be sustained in the virus population when the progeny viruses of different co-infections were used as inocula to infect next passage larvae. These results show that the virulence parameters LD50, ST50 and virus production alone do not adequately reflect the competitiveness of the virus and are thus not suitable to describe virus population dynamics.

Animals↗

PubMed2004

Towards a molecular identification and classification system of lepidopteran-specific baculoviruses.

Virus genomics provides novel approaches for virus identification and classification. Based on the comparative analyses of sequenced lepidopteran-specific baculovirus genomes, degenerate oligonucleotides were developed that allow the specific amplification of several regions of the genome using polymerase chain reaction (PCR) followed by DNA sequencing. The DNA sequences within the coding regions of three highly conserved genes, namely polyhedrin/granulin (polh/gran), late expression factor 8 (lef-8), and late expression factor 9 (lef-9), were targeted for amplification. The oligonucleotides were tested on viral DNAs isolated from historical field samples, and amplification products were generated from 12 isolated nucleopolyhedrovirus (NPV) and 8 granulovirus (GV) DNAs. The PCR products were cloned or directly sequenced, and phylogenetic trees were inferred from individual and combined data sets of these three genes and compared to a phylogeny, which includes 22 baculoviruses using a combined data set of 30 core genes. This method allows a fast and reliable detection and identification of lepidopteran-specific NPVs and GVs. Furthermore, a strong correlation of the base composition of these three genome areas with that of the complete virus genome was observed and used to predict the base composition of uncharacterized baculovirus genomes. These analyses suggested that GVs have a significantly higher AT content than NPVs.

Animals↗

PubMed2004

Characterization and phylogenetic analysis of the chitinase gene from the Helicoverpa armigera single nucleocapsid nucleopolyhedrovirus.

A putative chitinase gene was identified within the fragment EcoRI-K of the Helicoverpa armigera single-nucleocapsid nucleopolyhedrovirus (HearNPV, also called HaSNPV) genome. The open reading frame (ORF) contains 1713 nucleotides (nt) and encodes a protein of 570 amino acids (aa) with a predicted molecular weight of 63.6 kDa. Transcription started at about 18 h post infection (p.i.) and the protein was first detected at 20 h p.i. The times of transcription and expression are characteristic of a late baculovirus gene. 5' and 3' RACE indicated that transcription was initiated from the adenine residue located at -246 nt upstream from the ATG start site and the poly (A) tail was added at 267 nt downstream from the stop codon. This is the first report on the molecular characterization of a chitinase from a single nucleocapsid NPV. The phylogeny of baculoviral chitinase genes were extensively examined in comparison with chitinases derived from bacteria, fungi, nematode, actinomycetes, viruses, insects and mammals. Neighbor-joining and most parsimony analyses showed that the baculoviral chitinases were clustered exclusively within gamma-proteobacteria. Our results strongly suggest that baculoviruses acquired their chitinase genes from bacteria.

Amino Acid Sequence↗

PubMed2004

The mosaic structure of the polyhedrin gene of the Autographa californica nucleopolyhedrovirus (AcMNPV).

The polyhedrin (polh) gene of nucleopolyhedroviruses (NPVs) encodes for the matrix protein of the virus occlusion body and is one of the most conserved baculovirus genes. Previous analyses of different NPV genes and polh genes provided conflicting results indicating that the Autographa californica nucleopolyhedrovirus (AcMNPV) is generally a member of the so-called group I NPVs and is most closely related to Rachiplusia ou (Ro) NPV, whereas the AcMNPV polh is more similar to the polh of the group II NPVs. A comparative analysis of the AcMNPV polh and its closest neighbours within group I and group II NPV, the RoMNPV and the Thysanoplusia orichalcea (Thor) NPV, was performed using Hidden Markov Models for detecting recombination. The result provided strong evidence that the AcMNPV polh is a chimerical gene which consists of a mosaic of group I and group II NPV specific sequences.

Animals↗

PubMed2003

The genome of the Cryptophlebia leucotreta granulovirus.

The genome of the Cryptophlebia leucotreta granulovirus (CrleGV) was sequenced and analyzed. The double-stranded circular genome contains 110907 bp and potentially encodes 129 predicted open reading frames (ORFs), 124 of which were similar to other baculovirus ORFs. Five ORFs were CrleGV specific and 26 ORFs were common to other granulovirus genomes. One ORF showed a significant similarity to a nonstructural protein of Bombyx mori densovirus-2. A baculovirus chitinase gene was identified, which is most likely not functional, because its central coding region including the conserved chitinase active site signature is deleted. Three gene copies (Crle20, 23, and 24) containing the Baculo PEP N domain of the polyhedron envelope protein were identified in CrleGV and other GV genomes. One of them (Crle23) appeared also to contain a p10-like sequence encoding of a number of leucine-rich heptad repeats and a proline-rich domain. Another striking feature of the genome is the presence of a hypervariable non-hr ori-like region of about 1800 bp consisting of different kinds of repeats and palindromes. Three other repeat-rich regions were identified within the genome and are considered as homologous regions (hrs). CrleGV is most closely related to the Cydia pomonella granulovirus (CpGV) as revealed by genome order comparisons and phylogenetic analyses. However, the AT content of the CrleGV genome, which is 67.6% and the highest found so far in baculoviruses, differed by 12.8% from the AT content of CpGV. This resulted in a major difference in the codon usage of both viruses and may reflect adaptive selection constraints to their particular hosts.

Amino Acid Sequence↗

PubMed2003

Comparative study on the susceptibility of cutworms (Lepidoptera: Noctuidae) to Agrotis segetum nucleopolyhedrovirus and Agrotis ipsilon nucleopolyhedrovirus.

The common cutworm (Agrotis segetum) and the black cutworm (Agrotis ipsilon) are serious soil pests of many vegetable and field crops all over the world. We have demonstrated the cross-infectivity of two baculoviruses, A. segetum nucleopolyhedrovirus (AgseNPV) and A. ipsilon nucleopolyhedrovirus (AgipNPV) for these two insect pests. The susceptibility of A. segetum to AgipNPV was confirmed by DNA restriction endonuclease analyses of DNA isolated from virus harvested from infected A. segetum larvae. For an initial comparison of both viruses, partial polyhedrin sequences were amplified by PCR, cloned, and sequenced. Both viruses shared a very similar polyhedrin gene sequence resulting in only three amino acid substitutions. Phylogenetic analyses clearly demonstrated that both viruses belong to NPV group II and are most closely related to a clade consisting of Spodoptera exigua NPV, Spodoptera frugiperda NPV, and Spodoptera littoralis NPV. Since AgipNPV shows high virulence for both cutworm species, it appears to be a suitable candidate as a single biological control agent of A. segetum and A. ipsilon.

Animals↗

PubMed2003

Morphological and molecular investigations of a microsporidium infecting the European grape vine moth, Lobesia botrana Den. et Schiff., and its taxonomic determination as Cystosporogenes legeri nov. comb.

We have isolated a microsporidium from a laboratory stock of the European grape vine moth, Lobesia botrana Den. et Schiff. (Lepidoptera, Tortricidae). Screening of this stock showed an infection rate of more than 90%, whereas field collected larvae from three different locations in Rhineland-Palatinate (Germany) did not demonstrate any signs of infection. Light and electron microscopic investigations of infected insects showed that gross pathology, morphology, and ultrastructure of the microsporidium are similar to those described earlier for Pleistophora legeri. Comparative phylogenetic analysis of the small subunit rDNA using maximum likelihood, maximum parsimony, and neighbour joining distance methods showed that our isolate was closely related to Cystosporogenes operophterae. Based on our morphological and molecular investigations we propose to rename this species Cystosporogenes legeri nov. comb.

Animals↗

PubMed2002

Homologous recombination between the inverted terminal repeats of defective transposon TCp3.2 causes an inversion in the genome of Cydia pomonella granulovirus.

In this study, a new mutant of the Cydia pomonella granulovirus (CpGV), which shows spontaneous inversion of a transposable element during in vivo replication, is described. CpGV-MCp4 is a natural mutant of CpGV-M, containing the transposable element TCp3.2, which originated from the genome of the host C. pomonella. During in vivo cloning studies of CpGV-MCp4, a mutant called CpGV-MCp4inv was isolated. CpGV-MCp4inv shows heterogeneity in the genome area of transposon insertion. Restriction mapping, PCR analysis and subsequent sequence analysis gave strong evidence that an inversion of TCp3.2 is caused by homologous recombination between the long inverted terminal repeats (ITRs) of the transposon. This finding demonstrated that extensive homologous repeat regions such as the ITRs of transposons cause inversions by homologous recombination during in vivo replication. The observed in vivo inversion between the ITRs can be considered as a model for the contribution of repeated sequences in the genome rearrangement of baculoviruses and a source for genetic heterogeneity among different baculoviruses and baculovirus genotypes.

Animals↗

PubMed2002

The expansion of a hypervariable, non-hr ori-like region in the genome of Cryptophlebia leucotreta granulovirus provides in vivo evidence for the utilization of baculovirus non-hr oris during replication.

In this report a naturally occurring hypervariable region within the genome of different Cryptophlebia leucotreta granulovirus genotypes is characterized. The region consists of a stretch of direct repeats, short palindromes and an unusual AT-rich region. Although the organization of these repeat sequences is unique to baculoviruses, it has the structural features of a 'non-hr' origin of DNA replication (ori). Restriction analysis and Southern hybridization revealed that this region is expanded during virus replication. Sequence comparison of different isolated genotypes indicated that the expansion is caused by concatenation of short repeats within the region or by concatenation of the complete region. These findings indicate that the expansion of non-hr origin-like regions is not restricted to defective-interfering particles, as was found previously for baculoviruses propagated in cell culture. Moreover, it appears that non-hr complexity contributes to the natural heterogeneity and genetic plasticity of baculovirus genomes. Also, circumstantial evidence is discussed that hr oris might have developed from internal rearrangement and multiplication of a non-hr ori during baculovirus evolution.

Amino Acid Sequence↗