Insect-transmitted pathogens in the insect midgut

1996 ◽  
pp. 432-462 ◽  
Author(s):  
D. C. Kaslow ◽  
S. Welburn
Keyword(s):  
Insect Midgut

Identification of a baculovirus polyhedron formation mutant with a novel phenotype

1996 ◽  
Vol 54 ◽  
pp. 796-797
Author(s):  
James M. Slavicek ◽  
Melissa J. Mercer ◽  
Mary Ellen Kelly
Keyword(s):  
Viral Gene ◽  
Gene Products ◽  
Type Number ◽  
Infection Cycle ◽  
Wild Type ◽  
Protein Matrix ◽  
Insect Midgut ◽  
Viral Particles ◽  
Budded Virus ◽  
Viral Form

Nucleopolyhedroviruses (NPV, family Baculoviridae) produce two morphological forms, a budded virus form and a viral form that is occluded into a paracrystalline protein matrix. This structure is termed a polyhedron and is composed primarily of the protein polyhedrin. Insects are infected by NPVs after ingestion of the polyhedron and release of the occluded virions through dissolution of the polyhedron in the alkaline environment of the insect midgut. Early after infection the budded virus form is produced. It buds through the plasma membrane and then infects other cells. Later in the infection cycle the occluded form of the virus is generated (reviewed by Blissard and Rohrmann, 1990).The processes of polyhedron formation and virion occlusion are likely to involve a number of viral gene products. However, only two genes, the polyhedrin gene and 25K FP gene, have been identified to date that are necessary for the wild type number of polyhedra to be formed and viral particles occluded.

scholarly journals Bacmid Expression of Granulovirus Enhancin En3 Accumulates in Cell Soluble Fraction to Potentiate Nucleopolyhedrovirus Infection

Viruses ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1233
Author(s):  
Adriana Ricarte-Bermejo ◽  
Oihane Simón ◽  
Ana Beatriz Fernández ◽  
Trevor Williams ◽  
Primitivo Caballero
Keyword(s):  
Trichoplusia Ni ◽  
Recombinant Virus ◽  
Spodoptera Exigua ◽  
Insect Cells ◽  
Soluble Fraction ◽  
Autographa Californica ◽  
Insect Midgut ◽  
Baculovirus Infection ◽  
Occlusion Bodies ◽  
Infected Cells

Enhancins are metalloproteinases that facilitate baculovirus infection in the insect midgut. They are more prevalent in granuloviruses (GVs), constituting up to 5% of the proteins of viral occlusion bodies (OBs). In nucleopolyhedroviruses (NPVs), in contrast, they are present in the envelope of the occlusion-derived virions (ODV). In the present study, we constructed a recombinant Autographa californica NPV (AcMNPV) that expressed the Trichoplusia ni GV (TnGV) enhancin 3 (En3), with the aim of increasing the presence of enhancin in the OBs or ODVs. En3 was successfully produced but did not localize to the OBs or the ODVs and accumulated in the soluble fraction of infected cells. As a result, increased OB pathogenicity was observed when OBs were administered in mixtures with the soluble fraction of infected cells. The mixture of OBs and the soluble fraction of Sf9 cells infected with BacPhEn3 recombinant virus was ~3- and ~4.7-fold more pathogenic than BacPh control OBs in the second and fourth instars of Spodoptera exigua, respectively. In contrast, when purified, recombinant BacPhEn3 OBs were as pathogenic as control BacPh OBs. The expression of En3 in the soluble fraction of insect cells may find applications in the development of virus-based insecticides with increased efficacy.

Intracellular life cycle of Candidatus Liberibacter asisticus inside psyllid gut cells

2021 ◽  
Author(s):  
Lin Chun-Yi ◽  
Diann Achor ◽  
Amit Levy
Keyword(s):  
Molecular Mechanisms ◽  
Management Strategies ◽  
Bacterial Invasion ◽  
Diaphorina Citri ◽  
Current Management ◽  
Insect Midgut ◽  
Rapid Spread ◽  
Candidatus Liberibacter ◽  
Infected Insect ◽  
Liberibacter Asiaticus

Candidatus Liberibacter asiaticus (CLas), the devastating pathogen related to Huanglongbing (HLB), is a phloem-limited, fastidious, insect-borne bacterium. Rapid spread of HLB disease relies on CLas propagates efficiently in its vector, the Asian citrus psyllid, Diaphorina citri, in a circulative manner. Understanding the intracellular lifecycle of CLas in psyllid midgut is fundamental to improve current management strategies. Using a microscopic approach within CLas-infected insect midgut, we observed the entry of CLas into gut cells inside vesicles by endocytosis, termed Liberibacter containing vacuoles (LCVs). Endocytosis is followed by the formation of endoplasmic reticulum-related and replication permissive vacuoles (rLCVs). rLCVs then further develop into bigger double membrane autophagosome-like structure, termed autophagy-related vacuole (aLCV). Vesicles, containing CLas egress from aLCV and fuse with the cell membrane. Immunolocalization studies showed that CLas employs endo/exocytosis-like mechanisms that mediates bacterial invasion and egress. Upregulation of autophagy-related genes indicated subversion of host autophagy by CLas in psyllid vector to promote infection. These results indicate that CLas interacts with host cellular machineries to undergo a multistage intracellular cycle through endocytic, secretory, autophagic and exocytic pathways via complex machineries. Potential tactics for HLB controlling can be made depending on further investigations on the knowledge of the molecular mechanisms of CLas intracellular cycle.

Antigenic variation in its biological context

1984 ◽  
Vol 307 (1131) ◽  
pp. 27-40 ◽  
Keyword(s):  
Salivary Glands ◽  
Antigenic Variation ◽  
Tsetse Fly ◽  
Mammalian Host ◽  
Full Understanding ◽  
Anamnestic Response ◽  
Insect Midgut ◽  
The Relationship ◽  
Biological Context

The biology of antigenic variation is discussed, and the problems that must be solved to provide a full understanding of antigenic variation are considered. These are (i) the induction of v.s.g. synthesis in the salivary glands of the tsetse fly; (ii) the nature of the restriction on v.s.g. genes that allows only some of them to be expressed in the salivary glands; (iii) the nature of ‘predominance’ in v.s.g. expression in the mammalian host, and the mechanism by which it operates; (iv) the repression of v.s.g. synthesis in the insect midgut; (v) the anamnestic response that produces expression of the ingested variant in the first patent parasitaemia in the mammalian host; (vi) the mechanism by which only one v.s.g. gene at a time is expressed; (vii) the relationship if any ofv.s.g. structure to v.s.g.-associated differences in growth rate and host range; (viii) the role of v.s.g. release within the life cycle and to pathogenesis.

Bauhinia Proteinase Inhibitor-Based Synthetic Fluorogenic Substrates for Enzymes Isolated from Insect Midgut and Caterpillar Bristles

2003 ◽  
Vol 384 (3) ◽  
Author(s):  
S.A. Andrade ◽  
E.M. Santomauro-Vaz ◽  
A.R. Lopes ◽  
A.M. Chudzinski-Tavassi ◽  
M.A. Juliano ◽  
...  
Keyword(s):  
Proteinase Inhibitor ◽  
Fluorogenic Substrates ◽  
Insect Midgut

scholarly journals Evaluation of Chemical Strategies for Improving the Stability and Oral Toxicity of Insecticidal Peptides

Biomedicines ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 90 ◽  
Author(s):  
Volker Herzig ◽  
Aline de Araujo ◽  
Kathryn Greenwood ◽  
Yanni Chin ◽  
Monique Windley ◽  
...  
Keyword(s):  
Oral Toxicity ◽  
Peptide Backbone ◽  
Insect Midgut ◽  
Peptide Toxins ◽  
Oral Activity ◽  
The Stability ◽  
Reduced Rate ◽  
Chemical Strategies ◽  
Orally Active ◽  
Insecticidal Peptides

Spider venoms are a rich source of insecticidal peptide toxins. Their development as bioinsecticides has, however, been hampered due to concerns about potential lack of stability and oral bioactivity. We therefore systematically evaluated several synthetic strategies to increase the stability and oral potency of the potent insecticidal spider-venom peptide ω-HXTX-Hv1a (Hv1a). Selective chemical replacement of disulfide bridges with diselenide bonds and N- to C-terminal cyclization were anticipated to improve Hv1a resistance to proteolytic digestion, and thereby its activity when delivered orally. We found that native Hv1a is orally active in blowflies, but 91-fold less potent than when administered by injection. Introduction of a single diselenide bond had no effect on the susceptibility to scrambling or the oral activity of Hv1a. N- to C-terminal cyclization of the peptide backbone did not significantly improve the potency of Hv1a when injected into blowflies and it led to a significant decrease in oral activity. We show that this is likely due to a dramatically reduced rate of translocation of cyclic Hv1a across the insect midgut, highlighting the importance of testing bioavailability in addition to toxin stability.

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