transgenic-manipulation-arthropod-vectors-tools-to-study-vector-borne

Transgenic Manipulation of Arthropod Vectors: Tools to Study Vector-Borne Diseases

Dengue is the most important arthropod-borne viral infection in the Americas. In the last decades a progressive increment in dengue severity has been observed in Mexico and other countries of the region.

Dengue virus circulation and evolution in Mexico: a phylogenetic perspective.

Speichel Erwachsene weibliche Moskitos Hilfe Zucker und Blut F&uuml;tterung durch Enzyme und Polypeptide, die Zucker-Verdauung, helfen Steuern Wachstum von Mikroorganismen und ihre vertebrate Host Blutstillung und Entz&uuml;ndungen entgegenwirken. Moskito Speichel Spurenelement auch die &Uuml;bertragung des Vektors getragen Krankheitserreger, einschlie&szlig;lich Arboviruses. Culex Tarsalis ist ein Vogel F&uuml;tterung Moskito Vektor des West-Nil-Virus relativ eng mit C. Quinquefasciatus, eine M&uuml;cke F&uuml;tterns auf Mensch und der einzige M&uuml;cken der Gattung Culex, seine Sialotranscriptome, die bisher beschrieben haben vor kurzem angepasst.

Einen Einblick in die Sialotranscriptome des West-Nil-Moskito-Vektor, Culex Tarsalis.

Saliva of adult female mosquitoes help sugar and blood feeding by providing enzymes and polypeptides that help sugar digestion, control microbial growth and counteract their vertebrate host hemostasis and inflammation. Mosquito saliva also potentiates the transmission of vector borne pathogens, including arboviruses. Culex tarsalis is a bird feeding mosquito vector of West Nile Virus closely related to C. quinquefasciatus, a mosquito relatively recently adapted to feed on humans, and the only mosquito of the genus Culex to have its sialotranscriptome so far described.

An insight into the sialotranscriptome of the West Nile mosquito vector, Culex tarsalis.

Saliva of blood-sucking arthropods contains a complex mixture of peptides that affect their host's hemostasis, inflammation, and immunity. These activities can also modify the site of pathogen delivery and increase disease transmission. Saliva also induces hosts to mount an antisaliva immune response that can lead to skin allergies or even anaphylaxis. Accordingly, knowledge of the salivary repertoire, or sialome, of a mosquito is useful to provide a knowledge platform to mine for novel pharmacological activities, to develop novel vaccine targets for vector-borne diseases, and to develop epidemiological markers of vector exposure and candidate desensitization vaccines. The mosquito Ochlerotatus triseriatus is a vector of La Crosse virus and produces allergy in humans. In this work, a total of 1,575 clones randomly selected from an adult female O. triseriatus salivary gland cDNA library was sequenced and used to assemble a database that yielded 731 clusters of related sequences, 560 of which were singletons. Primer extension experiments were performed in selected clones to further extend sequence coverage, allowing for the identification of 159 protein sequences, 66 of which code for putative secreted proteins. Supplemental spreadsheets containing these data are available at http://exon.niaid.nih.gov/transcriptome/Ochlerotatus_triseriatus/S1/Ot-S1.xls and http://exon.niaid. nih.gov/transcriptome/Ochlerotatus_triseriatus/S2/Ot-S2.xls.

The salivary gland transcriptome of the eastern tree hole mosquito, Ochlerotatus triseriatus.

Speichel von blutsaugenden Gliederf&uuml;&szlig;ern enth&auml;lt ein komplexes Gemisch von Peptiden, die ihre Host Blutstillung, Entz&uuml;ndung und Immunit&auml;t zu beeinflussen. Diese T&auml;tigkeiten k&ouml;nnen auch Ortsbild des Erregers Lieferung &auml;ndern und &Uuml;bertragung von Krankheiten zu erh&ouml;hen. Speichel induziert auch Gastgeber eine antisaliva Immunantwort zu montieren, die Allergien oder sogar Anaphylaxie der Haut f&uuml;hren k&ouml;nnen. Kenntnisse &uuml;ber die Speicheldr&uuml;sen Repertoire oder Sialome, einer M&uuml;cke ist eine Wissensplattform f&uuml;r neuartige pharmakologische Aktivit&auml;ten, neuartige Impfstoff Ziele f&uuml;r Vektor-&uuml;bertragene Krankheiten zu entwickeln und epidemiologische Marker der Vektor Belichtung und Kandidat Desensibilisierung Impfstoffe zu entwickeln mir gew&auml;hrleistet werden k&ouml;nnen. Die Moskito Synonyme Triseriatus ist ein Vektor von La Crosse Virus und produziert Allergie beim Menschen. In dieser Arbeit war insgesamt 1.575 Klone, die zuf&auml;llig ausgew&auml;hlt aus einer erwachsenen Frau O. Triseriatus Speicheldr&uuml;se cDNA Bibliothek sequenziert und verwendet, um eine Datenbank zu montieren, 731 Cluster von verwandte Sequenzen, 560 davon Singletons wurden die zu. Grundierung Erweiterung Experimente wurden durchgef&uuml;hrt in ausgew&auml;hlten Klone Sequenz Abdeckung, erm&ouml;glicht die Identifizierung von 159 Proteinsequenzen, weiter ausbauen 66 von welcher Code f&uuml;r vermeintliche sekretierten Proteine. Zus&auml;tzliche Tabellen, die mit diesen Daten stehen unter http://exon.niaid.nih.gov/transcriptome/Ochlerotatus_triseriatus/S1/Ot-S1.xls und http://exon.niaid. nih.gov/transcriptome/Ochlerotatus_triseriatus/S2/Ot-S2.xls.

Die Speicheldr&uuml;se Transkriptom des &ouml;stlichen Baum Loch Moskitos, Synonyme Triseriatus.

Mosquito-borne viral diseases cause significant burden in much of the developing world. Although host-virus interactions have been studied extensively in the vertebrate host, little is known about mosquito responses to viral infection. In contrast to mosquitoes of the Aedes and Culex genera, Anopheles gambiae, the principal vector of human malaria, naturally transmits very few arboviruses, the most important of which is O'nyong-nyong virus (ONNV). Here we have investigated the A. gambiae immune response to systemic ONNV infection using forward and reverse genetic approaches.

Anopheles gambiae antiviral immune response to systemic O'nyong-nyong infection.

RNA interference (RNAi) was shown over 18 years ago to be a mechanism by which arbovirus replication and transmission could be controlled in arthropod vectors. During the intervening period, research on RNAi has defined many of the components and mechanisms of this antiviral pathway in arthropods, yet a number of unexplored questions remain. RNAi refers to RNA-mediated regulation of gene expression. Originally, the term described silencing of endogenous genes by introduction of exogenous double-stranded (ds)RNA with the same sequence as the gene to be silenced. Further research has shown that RNAi comprises three gene regulation pathways that are mediated by small RNAs: the small interfering (si)RNA, micro (mi)RNA, and Piwi-interacting (pi)RNA pathways. The exogenous (exo-)siRNA pathway is now recognized as a major antiviral innate immune response of arthropods. More recent studies suggest that the piRNA and miRNA pathways might also have important roles in arbovirus-vector interactions. This review will focus on current knowledge of the role of the exo-siRNA pathway as an arthropod vector antiviral response and on emerging research into vector piRNA and miRNA pathway modulation of arbovirus-vector interactions. Although it is assumed that arboviruses must evade the vector's antiviral RNAi response in order to maintain their natural transmission cycles, the strategies by which this is accomplished are not well defined. RNAi is also an important tool for arthropod gene knock-down in functional genomics studies and in development of arbovirus-resistant mosquito populations. Possible arbovirus strategies for evasion of RNAi and applications of RNAi in functional genomics analysis and arbovirus transmission control will also be reviewed. 

The role of RNA interference (RNAi) in arbovirus-vector interactions.

Arthropod-borne (arbo) viruses infect hematophagous arthropods (vectors) to maintain virus transmission between vertebrate hosts. The mosquito vector actively controls arbovirus infection to minimize its fitness costs. The RNA interference (RNAi) pathway is the major antiviral response vectors use to restrict arbovirus infections. We know this because depleting RNAi gene products profoundly impacts arbovirus replication, the antiviral RNAi pathway genes undergo positive, diversifying selection and arboviruses have evolved strategies to evade the vector's RNAi responses. The vector's RNAi defense and arbovirus countermeasures lead to an arms race that prevents potential virus-induced fitness costs yet maintains arbovirus infections needed for transmission. This review will discuss the latest findings in RNAi-arbovirus interactions in the model insect (Drosophila melanogaster) and in specific mosquito vectors. 

Arbovirus-mosquito interactions: RNAi pathway.

New World arenaviruses cause fatal hemorrhagic disease in South America. Pirital virus (PIRV), a mammarenavirus hosted by Alston&rsquo;s cotton rat (), causes a disease in Syrian golden hamsters () (biosafety level-3, BSL-3) that has many pathologic similarities to the South American hemorrhagic fevers (BSL-4) and, thus, is considered among the best small-animal models for human arenavirus disease. Here, we extend in greater detail previously described clinical and pathological findings in Syrian hamsters and provide evidence for a pro-inflammatory macrophage response during PIRV infection. The liver was the principal target organ of the disease, and signs of Kupffer cell involvement were identified in mortally infected hamster histopathology data. Differential expression analysis of liver mRNA revealed signatures of the pro-inflammatory response, hematologic dysregulation, interferon pathway and other host response pathways, including 17 key transcripts that were also reported in two non-human primate (NHP) arenavirus liver-infection models, representing both Old and New World mammarenavirus infections. Although antigen presentation may differ among rodent and NHP species, key hemostatic and innate immune-response components showed expression parallels. Signatures of pro-inflammatory macrophage involvement in PIRV-infected livers included enrichment of , , , , , , , and  transcripts. Together, these data indicate that pro-inflammatory macrophage M1 responses likely contribute to the pathogenesis of acute PIRV infection.

Involvement of Pro-Inflammatory Macrophages in Liver Pathology of Pirital Virus-Infected Syrian Hamsters.

Chikungunya virus (CHIKV) is a medically important mosquito-borne virus transmitted to humans by infected  () species. In 2013⁻2014,  transmitted CHIKV to humans in the Caribbean and in 2005⁻2006,  transmitted CHIKV on La Réunion Island (Indian Ocean basin). CHIKV LR2006 OPY1 from the La Réunion epidemic was associated with a mutation (E1:A226V) in the viral E1 glycoprotein that enhanced CHIKV transmission by . CHIKV R99659 from the Caribbean outbreak did not have the E1:A226V mutation. Here, we analyzed the salivary glands and saliva of  strains from New Jersey, Florida, Louisiana and La Réunion after infection with each virus to determine their transmission potential. We infected the  strains with blood meals containing 3⁻7 × 10⁷ PFU/mL of each virus and analyzed the mosquitoes nine days later to maximize infection of their salivary glands. All four  strains were highly susceptible to LR2006 OPY1 and R99659 viruses and their CHIKV disseminated infection rates (DIR) were statistically similar ( = 0.3916). The transmission efficiency rate (TER) was significantly lower for R99659 virus compared to LR2006 OPY1 virus in all  strains and  (Poza Rica) ( = 0.012) suggesting a salivary gland exit barrier to R99659 virus not seen with LR2006 OPY1 infections. If introduced, LR2006 OPY1 virus poses an increased risk of transmission by both  species in the western hemisphere.

Analysis of Salivary Glands and Saliva from  and  Infected with Chikungunya Viruses.

The yellow fever mosquito, Aedes aegypti, serves as the primary vector for epidemic transmission of yellow fever, dengue, Zika (ZIKV), and chikungunya viruses to humans. Control of Ae. aegypti is currently limited to insecticide applications and larval habitat management; however, to combat growing challenges with insecticide resistance, novel genetic approaches for vector population reduction or transmission interruption are being aggressively pursued. The objectives of this study were to assess the ability of the Ae. aegypti antiviral exogenous-small interfering RNA (exo-siRNA) response to inhibit ZIKV infection and transmission, and to identify the optimal RNA interference (RNAi) target region in the ZIKV genome. We accomplished these objectives by in vitro transcription of five long double-stranded RNAs (dsRNAs) from the genome region spanning the NS2B-NS3-NS4A genes, which were the most highly conserved among ZIKV RNA sequences representing both East and West African and Asian-American clades, and evaluation of the ability of these dsRNAs to trigger an effective antiviral exo-siRNA response after intrathoracic injection into Ae. aegypti. In a pilot study, five ZIKV dsRNAs were tested by intrathoracic inoculation of 250 ng dsRNA into groups of approximately 5-day-old mosquitoes. Three days post-inoculation, mosquitoes were provided an infectious blood-meal containing ZIKV strain PRVABC59 (Puerto Rico), MR766 (Uganda), or 41525 (Senegal). On days 7 and 14 post-infection individual whole mosquito bodies were assessed for ZIKV infectious titer by plaque assays. Based on the results of this initial assessment, three dsRNAs were selected for further evaluation of viral loads of matched body and saliva expectorants using a standardized infectious dose of 1 × 10 PFU/mL of each ZIKV strain. Fourteen days post-exposure to ZIKV, paired saliva and carcass samples were harvested from individual mosquitoes and assessed for ZIKV RNA load by qRT-PCR. Injection of each of the three dsRNAs resulted in significant inhibition of replication of all three strains of ZIKV in mosquito bodies and saliva. This study lays critical groundwork for pursuing ZIKV transmission-blocking strategies that exploit the Ae. aegypti exo-siRNA response for arbovirus suppression in natural populations.

Induction of RNA interference to block Zika virus replication and transmission in the mosquito Aedes aegypti.

Viral infection of the central nervous system (CNS) can cause lasting neurological decline in surviving patients and can present with symptoms resembling Parkinson's disease (PD). The mechanisms underlying postencephalitic parkinsonism remain unclear but are thought to involve increased innate inflammatory signaling in glial cells, resulting in persistent neuroinflammation. We therefore studied the role of glial cells in regulating neuropathology in postencephalitic parkinsonism by studying the involvement of astrocytes in loss of dopaminergic neurons and aggregation of α-synuclein protein following infection with western equine encephalitis virus (WEEV). Infections were conducted in both wildtype mice and in transgenic mice lacking NFκB inflammatory signaling in astrocytes. For 2 months following WEEV infection, we analyzed glial activation, neuronal loss and protein aggregation across multiple brain regions, including the substantia nigra pars compacta (SNpc). These data revealed that WEEV induces loss of SNpc dopaminergic neurons, persistent activation of microglia and astrocytes that precipitates widespread aggregation of α-synuclein in the brain of C57BL/6 mice. Microgliosis and macrophage infiltration occurred prior to activation of astrocytes and was followed by opsonization of ⍺-synuclein protein aggregates in the cortex, hippocampus and midbrain by the complement protein, C3. Astrocyte-specific NFκB knockout mice had reduced gliosis, α-synuclein aggregate formation and neuronal loss. These data suggest that astrocytes play a critical role in initiating PD-like pathology following encephalitic infection with WEEV through innate immune inflammatory pathways that damage dopaminergic neurons, possibly by hindering clearance of ⍺-synuclein aggregates. Inhibiting glial inflammatory responses could therefore represent a potential therapy strategy for viral parkinsonism.

Astrocyte inflammatory signaling mediates α-synuclein aggregation and dopaminergic neuronal loss following viral encephalitis.

Herein we describe a previously uninvestigated salivary gland escape barrier (SEB) in Culex tarsalis mosquitoes infected with two different strains of Western equine encephalitis virus (WEEV). The WEEV strains were originally isolated either from mosquitoes (IMP181) or a human patient (McMillan). Both IMP181 and McMillan viruses were fully able to infect the salivary glands of Culex tarsalis after intrathoracic injection as determined by expression of mCherry fluorescent protein. IMP181, however, was better adapted to transmission as measured by virus titer in saliva as well as transmission rates in infected mosquitoes. We used chimeric recombinant WEEV strains to show that inclusion of IMP181-derived structural genes partially circumvents the SEB.

Article	Year
Dengue virus circulation and evolution in Mexico: a phylogenetic perspective. Archives of medical research\| PubMed ID: 16824937	2006
An insight into the sialotranscriptome of the West Nile mosquito vector, Culex tarsalis. BMC genomics\| PubMed ID: 20089177	2010
The salivary gland transcriptome of the eastern tree hole mosquito, Ochlerotatus triseriatus. Journal of medical entomology\| PubMed ID: 20496585	2010
Anopheles gambiae antiviral immune response to systemic O'nyong-nyong infection. PLoS neglected tropical diseases\| PubMed ID: 22428080	2012
The role of RNA interference (RNAi) in arbovirus-vector interactions. Viruses\| PubMed ID: 25690800
Arbovirus-mosquito interactions: RNAi pathway. Current opinion in virology\| PubMed ID: 26629932
Involvement of Pro-Inflammatory Macrophages in Liver Pathology of Pirital Virus-Infected Syrian Hamsters. Viruses\| PubMed ID: 29724035
Analysis of Salivary Glands and Saliva from and Infected with Chikungunya Viruses. Insects\| PubMed ID: 30717086
Induction of RNA interference to block Zika virus replication and transmission in the mosquito Aedes aegypti. Insect biochemistry and molecular biology\| PubMed ID: 31103782	2019
Astrocyte inflammatory signaling mediates α-synuclein aggregation and dopaminergic neuronal loss following viral encephalitis. Experimental neurology\| PubMed ID: 34454938	2021
Identification of salivary gland escape barriers to western equine encephalitis virus in the natural vector, Culex tarsalis. PloS one\| PubMed ID: 35298486	2022

Kenneth E. Olson

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