scholarly journals Filamentous Structures Induced by a Phytoreovirus Mediate Viral Release from Salivary Glands in Its Insect Vector

2017 ◽  
Vol 91 (12) ◽  
Author(s):  
Qianzhuo Mao ◽  
Zhenfeng Liao ◽  
Jiajia Li ◽  
Yuyan Liu ◽  
Wei Wu ◽  
...  
Keyword(s):  
Salivary Gland ◽  
Salivary Glands ◽  
Viral Transmission ◽  
Insect Vector ◽  
Insect Vectors ◽  
Viral Control ◽  
Content Type ◽  
Viral Release ◽  
Persistent Viruses ◽  
Membrane Barrier

ABSTRACT Numerous viral pathogens are persistently transmitted by insect vectors and cause agricultural or health problems. These viruses circulate in the vector body, enter the salivary gland, and then are released into the apical plasmalemma-lined cavities, where saliva is stored. The cavity plasmalemma of vector salivary glands thus represents the last membrane barrier for viral transmission. Here, we report a novel mechanism used by a persistent virus to overcome this essential barrier. We observed that the infection by rice gall dwarf virus (RGDV), a species of the genus Phytoreovirus in the family Reoviridae, induced the formation of virus-associated filaments constructed by viral nonstructural protein Pns11 within the salivary glands of its leafhopper vector, Recilia dorsalis. Such filaments attached to actin-based apical plasmalemma and induced an exocytosis-like process for viral release into vector salivary gland cavities, through a direct interaction of Pns11 of RGDV and actin of R. dorsalis. Failure of virus-induced filaments assembly by RNA interference with synthesized double-stranded RNA targeting the Pns11 gene inhibited the dissemination of RGDV into salivary cavities, preventing viral transmission by R. dorsalis. For the first time, we show that a virus can exploit virus-induced inclusion as a vehicle to pass through the apical plasmalemma into vector salivary gland cavities, thus overcoming the last membrane barrier for viral transmission by insect vectors. IMPORTANCE Understanding how persistent viruses overcome multiple tissue and membrane barriers within the insect vectors until final transmission is the key for viral disease control. The apical plasmalemma of the cavities where saliva is stored in the salivary glands is the last barrier for viral transmission by insect vectors; however, the mechanism is still poorly understood. Here we show that a virus has evolved to exploit virus-induced filaments to perform an exocytosis-like process that enables viral passage through the apical plasmalemma into salivary cavities. This mechanism could be extensively exploited by other persistent viruses to overcome salivary gland release barriers in insect vectors, opening new perspectives for viral control.

scholarly journals Viral Release Threshold in the Salivary Gland of Leafhopper Vector Mediates the Intermittent Transmission of Rice Dwarf Virus

2021 ◽  
Vol 12 ◽  
Author(s):  
Qian Chen ◽  
Yuyan Liu ◽  
Zhirun Long ◽  
Hengsong Yang ◽  
Taiyun Wei
Keyword(s):  
Salivary Gland ◽  
Salivary Glands ◽  
Horizontal Transmission ◽  
Dwarf Virus ◽  
Insect Vectors ◽  
Rice Dwarf Virus ◽  
Leafhopper Vector ◽  
Gland Cells ◽  
Viral Release ◽  
Salivary Gland Cells

Numerous piercing-sucking insects can persistently transmit viral pathogens in combination with saliva to plant phloem in an intermittent pattern. Insect vectors maintain viruliferous for life. However, the reason why insect vectors discontinuously transmit the virus remains unclear. Rice dwarf virus (RDV), a plant reovirus, was found to replicate and assemble the progeny virions in salivary gland cells of the leafhopper vector. We observed that the RDV virions moved into saliva-stored cavities in the salivary glands of leafhopper vectors via an exocytosis-like mechanism, facilitating the viral horizontal transmission to plant hosts during the feeding of leafhoppers. Interestingly, the levels of viral accumulation in the salivary glands of leafhoppers during the transmitting period were significantly lower than those of viruliferous individuals during the intermittent period. A putative viral release threshold, which was close to 1.79 × 104 copies/μg RNA was proposed from the viral titers in the salivary glands of 52 leafhoppers during the intermittent period. Thus, the viral release threshold was hypothesized to mediate the intermittent release of RDV from the salivary gland cells of leafhoppers. We anticipate that viral release threshold-mediated intermittent transmission by insect vectors is the conserved strategy for the epidemic and persistence of vector-borne viruses in nature.

scholarly journals Disruption of Plasmodium Sporozoite Transmission by Depletion of Sporozoite Invasion-Associated Protein 1

2009 ◽  
Vol 8 (4) ◽  
pp. 640-648 ◽  
Author(s):  
Sabine Engelmann ◽  
Olivier Silvie ◽  
Kai Matuschewski
Keyword(s):  
Salivary Gland ◽  
Salivary Glands ◽  
Gliding Motility ◽  
Insect Vector ◽  
Targeted Disruption ◽  
Apicomplexan Parasites ◽  
Complex Development ◽  
Fluorescent Tagging ◽  
And Migration

ABSTRACT Accumulation of infectious Plasmodium sporozoites in Anopheles spp. salivary glands marks the final step of the complex development of the malaria parasite in the insect vector. Sporozoites are formed inside midgut-associated oocysts and actively egress into the mosquito hemocoel. Traversal of the salivary gland acinar cells correlates with the sporozoite's capacity to perform continuous gliding motility. Here, we characterized the cellular role of the Plasmodium berghei sporozoite invasion-associated protein 1 (SIAP-1). Intriguingly, SIAP-1 orthologs are found exclusively in apicomplexan hemoprotozoa, parasites that are transmitted by arthropod vectors, e.g., Plasmodium, Babesia, and Theileria species. By fluorescent tagging with mCherry, we show that SIAP-1 is expressed in oocyst-derived and salivary gland-associated sporozoites, where it accumulates at the apical tip. Targeted disruption of SIAP-1 does not affect sporozoite formation but causes a partial defect in sporozoite egress from oocysts and abolishes sporozoite colonization of mosquito salivary glands. Parasites with the siap-1(−) mutation are blocked in their capacity to perform continuous gliding motility. We propose that arthropod-transmitted apicomplexan parasites specifically express secretory factors, such as SIAP-1, that mediate efficient oocyst exit and migration to the salivary glands.

scholarly journals Variable Membrane Protein A of Flavescence Dorée Phytoplasma Binds the Midgut Perimicrovillar Membrane ofEuscelidius variegatusand Promotes Adhesion to Its Epithelial Cells

2018 ◽  
Vol 84 (8) ◽  
pp. e02487-17 ◽  
Author(s):  
Nathalie Arricau-Bouvery ◽  
Sybille Duret ◽  
Marie-Pierre Dubrana ◽  
Brigitte Batailler ◽  
Delphine Desqué ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Salivary Glands ◽  
Plant Pathogens ◽  
Insect Cells ◽  
Wild Plants ◽  
Insect Vector ◽  
Plant Host ◽  
Content Type ◽  
Flavescence Dorée ◽  
Fluorescent Beads

ABSTRACTPhytoplasmas are uncultivated plant pathogens and cell wall-less bacteria and are transmitted from plant to plant by hemipteran insects. The phytoplasma's circulative propagative cycle in insects requires the crossing of the midgut and salivary glands, and primary adhesion to cells is an initial step toward the invasion process. The flavescence dorée (FD) phytoplasma possesses a set of variable membrane proteins (Vmps) exposed on its surface, and this pathogen is suspected to interact with insect cells. The results showed that VmpA is expressed by the flavescence dorée phytoplasma present in the midgut and salivary glands. Phytoplasmas cannot be cultivated at present, and no mutant can be produced to investigate the putative role of Vmps in the adhesion of phytoplasma to insect cells. To overcome this difficulty, we engineered theSpiroplasma citrimutant G/6, which lacks the ScARP adhesins, for VmpA expression and used VmpA-coated fluorescent beads to determine if VmpA acts as an adhesin inex vivoadhesion assays andin vivoingestion assays. VmpA specifically interacted withEuscelidiusvariegatusinsect cells in culture and promoted the retention of VmpA-coated beads to the midgut ofE. variegatus. In this latest case, VmpA-coated fluorescent beads were localized and embedded in the perimicrovillar membrane of the insect midgut. Thus, VmpA functions as an adhesin that could be essential in the colonization of the insect by the FD phytoplasmas.IMPORTANCEPhytoplasmas infect a wide variety of plants, ranging from wild plants to cultivated species, and are transmitted by different leafhoppers, planthoppers, and psyllids. The specificity of the phytoplasma-insect vector interaction has a major impact on the phytoplasma plant host range. As entry into insect cells is an obligate process for phytoplasma transmission, the bacterial adhesion to insect cells is a key step. Thus, studying surface-exposed proteins of phytoplasma will help to identify the adhesins implicated in the specific recognition of insect vectors. In this study, it is shown that the membrane protein VmpA of the flavescence dorée (FD) phytoplasma acts as an adhesin that is able to interact with cells ofEuscelidiusvariegatus, the experimental vector of the FD phytoplasma.

scholarly journals Route of a Multipartite Nanovirus across the Body of Its Aphid Vector

2020 ◽  
Vol 94 (9) ◽  
Author(s):  
Jérémy Di Mattia ◽  
Marie-Stéphanie Vernerey ◽  
Michel Yvon ◽  
Elodie Pirolles ◽  
Mathilde Villegas ◽  
...  
Keyword(s):  
Salivary Gland ◽  
Salivary Glands ◽  
Plant Viruses ◽  
The Body ◽  
Insect Vector ◽  
Vector Transmission ◽  
Aphid Vector ◽  
Vector Interaction ◽  
Salivary Gland Cells ◽  
Mode Of Transmission

ABSTRACT Vector transmission plays a primary role in the life cycle of viruses, and insects are the most common vectors. An important mode of vector transmission, reported only for plant viruses, is circulative nonpropagative transmission whereby the virus cycles within the body of its insect vector, from gut to salivary glands and saliva, without replicating. This mode of transmission has been extensively studied in the viral families Luteoviridae and Geminiviridae and is also reported for Nanoviridae. The biology of viruses within these three families is different, and whether the viruses have evolved similar molecular/cellular virus-vector interactions is unclear. In particular, nanoviruses have a multipartite genome organization, and how the distinct genome segments encapsidated individually transit through the insect body is unknown. Here, using a combination of fluorescent in situ hybridization and immunofluorescence, we monitor distinct proteins and genome segments of the nanovirus Faba bean necrotic stunt virus (FBNSV) during transcytosis through the gut and salivary gland cells of its aphid vector Acyrthosiphon pisum. FBNSV specifically transits through cells of the anterior midgut and principal salivary gland cells, a route similar to that of geminiviruses but distinct from that of luteoviruses. Our results further demonstrate that a large number of virus particles enter every single susceptible cell so that distinct genome segments always remain together. Finally, we confirm that the success of nanovirus-vector interaction depends on a nonstructural helper component, the viral protein nuclear shuttle protein (NSP), which is shown to be mandatory for viral accumulation within gut cells. IMPORTANCE An intriguing mode of vector transmission described only for plant viruses is circulative nonpropagative transmission, whereby the virus passes through the gut and salivary glands of the insect vector without replicating. Three plant virus families are transmitted this way, but details of the molecular/cellular mechanisms of the virus-vector interaction are missing. This is striking for nanoviruses that are believed to interact with aphid vectors in ways similar to those of luteoviruses or geminiviruses but for which empirical evidence is scarce. We here confirm that nanoviruses follow a within-vector route similar to that of geminiviruses but distinct from that of luteoviruses. We show that they produce a nonstructural protein mandatory for viral entry into gut cells, a unique phenomenon for this mode of transmission. Finally, noting that nanoviruses are multipartite viruses, we demonstrate that a large number of viral particles penetrate susceptible cells of the vector, allowing distinct genome segments to remain together.

scholarly journals Purification of Plasmodium Sporozoites Enhances Parasite-Specific CD8+T Cell Responses

2016 ◽  
Vol 84 (8) ◽  
pp. 2233-2242 ◽  
Author(s):  
Zachary P. Billman ◽  
Annette M. Seilie ◽  
Sean C. Murphy
Keyword(s):  
T Cells ◽  
Salivary Gland ◽  
T Cell ◽  
Salivary Glands ◽  
Gradient Centrifugation ◽  
T Cell Responses ◽  
Inhibitory Effect ◽  
Content Type ◽  
Cell Responses ◽  
Lower Magnitude

Malaria infection caused byPlasmodiumparasites continues to cause enormous morbidity and mortality in areas where it is endemic, and there is no licensed vaccine capable of inducing sterile protection. Hyperimmunization with attenuated whole sporozoites can induce sterile protective immune responses targeting preerythrocytic antigens. Most animal models of hyperimmunization rely on sporozoites dissected from mosquito salivary glands and injected without further purification. In BALB/c mice, repeated small doses ofP. yoeliisporozoites progressively expand the population of sporozoite-specific CD8+T cells. In this study, large secondary doses of unpurified sporozoites unexpectedly led to contraction of sporozoite-specific CD8+T cell responses in sporozoite-primed mice. While sporozoite-primed CD8+T cells alternatively can be expanded by secondary exposure toListeria monocytogenesexpressing recombinantPlasmodiumantigens, such expansion was potently inhibited by coinjection of large doses of unpurified sporozoites and by uninfected salivary glands alone. Purification of sporozoites away from mosquito salivary gland debris by density gradient centrifugation eliminated salivary gland-associated inhibition. Thus, the inhibitory effect appears to be due to exposure to uninfected mosquito salivary glands rather than sporozoites. To further assess the effect of salivary gland exposure on later sporozoite vaccinations, mice were immunized with uninfected salivary glands from a single mosquito. Compared to naive mice, salivary gland presensitization reduced subsequent liver burdens by 71%. These data show that a component(s) in mosquito salivary glands reduces liver infection, thereby limiting antigen dose and contributing to lower-magnitude T cell responses. These findings suggest that sporozoite immunogenicity studies be performed using purified sporozoites whenever feasible.

scholarly journals Sequential production of gametes during meiosis in trypanosomes

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Lori Peacock ◽  
Chris Kay ◽  
Chloe Farren ◽  
Mick Bailey ◽  
Mark Carrington ◽  
...  
Keyword(s):  
Salivary Glands ◽  
Nuclear Dna ◽  
Nuclear Dna Content ◽  
Cell Types ◽  
Tsetse Fly ◽  
Binucleate Cell ◽  
Insect Vector ◽  
Content Ratio ◽  
Different Cell Types ◽  
Meiosis I

AbstractMeiosis is a core feature of eukaryotes that occurs in all major groups, including the early diverging excavates. In this group, meiosis and production of haploid gametes have been described in the pathogenic protist, Trypanosoma brucei, and mating occurs in the salivary glands of the insect vector, the tsetse fly. Here, we searched for intermediate meiotic stages among trypanosomes from tsetse salivary glands. Many different cell types were recovered, including trypanosomes in Meiosis I and gametes. Significantly, we found trypanosomes containing three nuclei with a 1:2:1 ratio of DNA contents. Some of these cells were undergoing cytokinesis, yielding a mononucleate gamete and a binucleate cell with a nuclear DNA content ratio of 1:2. This cell subsequently produced three more gametes in two further rounds of division. Expression of the cell fusion protein HAP2 (GCS1) was not confined to gametes, but also extended to meiotic intermediates. We propose a model whereby the two nuclei resulting from Meiosis I undergo asynchronous Meiosis II divisions with sequential production of haploid gametes.

scholarly journals Neurofibromin expression by normal salivary glands

2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Eloá Borges Luna ◽  
Pâmella Pinho Montovani ◽  
Rafaela Elvira Rozza-de-Menezes ◽  
Karin Soares Cunha
Keyword(s):  
Salivary Gland ◽  
Salivary Glands ◽  
Acinar Cells ◽  
Staining Intensity ◽  
Neurofibromatosis 1 ◽  
Tissue Type ◽  
Sublingual Gland ◽  
Minor Salivary Glands ◽  
Expression Levels ◽  
Ductal Cells

AbstractIntroductionNeurofibromin, a protein encoded by theNF1gene, is mutated in neurofibromatosis 1, one of the most common genetic diseases. Oral manifestations are common and a high prevalence of hyposalivation was recently described in individuals with neurofibromatosis 1. Although neurofibromin is ubiquitously expressed, its expression levels vary depending on the tissue type and developmental stage of the organism. The role of neurofibromin in the development, morphology, and physiology of salivary glands is unknown and a detailed expression of neurofibromin in human normal salivary glands has never been investigated.AimTo investigate the expression levels and distribution of neurofibromin in acinar and ductal cells of major and minor salivary glands of adult individuals without NF1.Material and methodTen samples of morphologically normal major and minor salivary glands (three samples of each gland: parotid, submandibular and minor salivary; and one sample of sublingual gland) from individuals without neurofibromatosis 1 were selected to assess neurofibromin expression through immunohistochemistry. Immunoquantification was performed by a digital method.ResultsNeurofibromin was expressed in the cytoplasm of both serous and mucous acinar cells, as well as in ducts from all the samples of salivary glands. Staining intensity varied from mild to strong depending on the type of salivary gland and region (acini or ducts). Ducts had higher neurofibromin expression than acinar cells (p = 0.003). There was no statistical association between the expression of neurofibromin and the type of the salivary gland, considering acini (p = 0.09) or ducts (p = 0.50) of the four salivary glands (parotid, submandibular, minor salivary, and sublingual gland). Similar results were obtained comparing the acini (p = 0.35) and ducts (p = 0.50) of minor and major salivary glands. Besides, there was no correlation between the expression of neurofibromin and age (p = 0.08), and sex (p = 0.79) of the individuals, considering simultaneously the neurofibromin levels of acini and duct (n = 34).ConclusionNeurofibromin is expressed in the cytoplasm of serous and mucous acinar cells, and ductal cells of salivary glands, suggesting that this protein is important for salivary gland function.

Trypanosome infections and survival in tsetse

Parasitology ◽  
1998 ◽  
Vol 116 (S1) ◽  
pp. S23-S28 ◽  
Author(s):  
I. Maudlin ◽  
S. C. Welburn ◽  
P. J. M. Milligan
Keyword(s):  
Salivary Gland ◽  
Salivary Glands ◽  
Trypanosoma Brucei ◽  
Glossina Morsitans Morsitans ◽  
Trypanosoma Congolense ◽  
Vectorial Capacity ◽  
Trypanosome Infection ◽  
Trypanosoma Brucei Rhodesiense ◽  
Glossina Morsitans ◽  
Differential Effects

SummaryThe effect of trypanosome infection on vector survival was observed in a line of Glossina morsitans morsitans selected for susceptibility to trypanosome infection. The differential effects of midgut and salivary gland infections on survival were examined by exposing flies to infection with either Trypanosoma congolense which colonizes midgut and mouthparts or Trypanosoma brucei rhodesiense which colonizes midgut and salivary glands. A comparison of the survival distributions of uninfected flies with those exposed to infection showed that salivary gland infection significantly reduces tsetse survival; midgut infection had little or no effect on the survival of tsetse. The significance of these findings is discussed in relation to the vectorial capacity of wild flies.

First Insights into the Molecular Basis of Pleomorphic Adenomas of the Salivary Glands

2000 ◽  
Vol 14 (1) ◽  
pp. 81-83 ◽  
Author(s):  
M.L. Voz ◽  
W.J.M. Van de Ven ◽  
K. Kas
Keyword(s):  
Salivary Gland ◽  
Salivary Glands ◽  
Benign Tumor ◽  
Salivary Gland Tumor ◽  
Transitional Zone ◽  
Chromosome 8 ◽  
Gland Tumor ◽  
Histopathological Classification ◽  
Pleomorphic Adenomas ◽  
Chromosomal Changes

Pleomorphic adenoma, or mixed tumor of the salivary glands, is a benign tumor originating from the major and minor salivary glands. Eighty-five percent of these tumors are found in the parotid gland, 10% in the minor (sublingual) salivary glands, and 5% in the submandibular gland. It is the most common type of salivary gland tumor, accounting for almost 50% of all neoplasms in these organs. In fact, after the first observation of recurrent loss of chromosome 22 in meningioma, this was the second type of benign tumor for which non-random chromosomal changes were reported. The rate of malignant change with the potential to metastasize has been reported to be only 2 to 3%, and only a few cases of metastasizing pleomorphic salivary gland adenomas have been described to date. The fact that these tumors arise in organs located in an ontogenetic transitional zone, a region where endoderm and ectoderm meet, might be one of the reasons for the often-problematic histopathological classification. This type of benign tumor has been cytogenetically very well-characterized, with several hundreds of tumors karyotyped. In addition to the cytogenetic subgroup with an apparently normal diploid stemline (making up approximately 30% of the cases), three major cytogenetic subgroups can be distinguished. In addition to a subgroup showing non-recurrent clonal abnormalities, another subgroup is composed of tumors with various translocations involving 12ql5. By far the largest cytogenetic subgroup, however, consists of tumors with chromosome 8 abnormalities, mainly showing translocations involving region 8ql2. The most frequently encountered aberration in this group is a t(3;8)(p21;q12).

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