Bunyavirus-Vector Interactions

Citation: Horne, K.M.; Vanlandingham, D.L. Bunyavirus-Vector Interactions. Viruses 2014, 6, 4373-4397.The Bunyaviridae family is comprised of more than 350 viruses, of which many within the Hantavirus, Orthobunyavirus, Nairovirus, Tospovirus, and Phlebovirus genera are significant human or agricultural pathogens. The viruses within the Orthobunyavirus, Nairovirus, and Phlebovirus genera are transmitted by hematophagous arthropods, such as mosquitoes, midges, flies, and ticks, and their associated arthropods not only serve as vectors but also as virus reservoirs in many cases. This review presents an overview of several important emerging or re-emerging bunyaviruses and describes what is known about bunyavirus-vector interactions based on epidemiological, ultrastructural, and genetic studies of members of this virus family

Identification of microRNAs expressed in two mosquito vectors, Aedes albopictus and Culex quinquefasciatus

<p>Abstract</p> <p>Background</p> <p>MicroRNAs (miRNAs) are small non-coding RNAs that post-transcriptionally regulate gene expression in a variety of organisms, including insects, vertebrates, and plants. miRNAs play important roles in cell development and differentiation as well as in the cellular response to stress and infection. To date, there are limited reports of miRNA identification in mosquitoes, insects that act as essential vectors for the transmission of many human pathogens, including flaviviruses. West Nile virus (WNV) and dengue virus, members of the <it>Flaviviridae </it>family, are primarily transmitted by <it>Aedes </it>and <it>Culex </it>mosquitoes. Using high-throughput deep sequencing, we examined the miRNA repertoire in <it>Ae. albopictus </it>cells and <it>Cx. quinquefasciatus </it>mosquitoes.</p> <p>Results</p> <p>We identified a total of 65 miRNAs in the <it>Ae. albopictus </it>C7/10 cell line and 77 miRNAs in <it>Cx. quinquefasciatus </it>mosquitoes, the majority of which are conserved in other insects such as <it>Drosophila melanogaster </it>and <it>Anopheles gambiae</it>. The most highly expressed miRNA in both mosquito species was miR-184, a miRNA conserved from insects to vertebrates. Several previously reported <it>Anopheles </it>miRNAs, including miR-1890 and miR-1891, were also found in <it>Culex </it>and <it>Aedes</it>, and appear to be restricted to mosquitoes. We identified seven novel miRNAs, arising from nine different precursors, in C7/10 cells and <it>Cx. quinquefasciatus </it>mosquitoes, two of which have predicted orthologs in <it>An. gambiae</it>. Several of these novel miRNAs reside within a ~350 nt long cluster present in both <it>Aedes </it>and <it>Culex</it>. miRNA expression was confirmed by primer extension analysis. To determine whether flavivirus infection affects miRNA expression, we infected female <it>Culex </it>mosquitoes with WNV. Two miRNAs, miR-92 and miR-989, showed significant changes in expression levels following WNV infection.</p> <p>Conclusions</p> <p><it>Aedes </it>and <it>Culex </it>mosquitoes are important flavivirus vectors. Recent advances in both mosquito genomics and high-throughput sequencing technologies enabled us to interrogate the miRNA profile in these two species. Here, we provide evidence for over 60 conserved and seven novel mosquito miRNAs, expanding upon our current understanding of insect miRNAs. Undoubtedly, some of the miRNAs identified will have roles not only in mosquito development, but also in mediating viral infection in the mosquito host.</p

Photochemical inactivation of chikungunya virus in human apheresis platelet components by amotosalen and UVA light

Chikungunya virus (CHIKV) is a mosquito-borne alphavirus that recently re-emerged in Africa and rapidly spread into countries of the Indian Ocean basin and South-East Asia. The mean viremic blood donation risk for CHIKV on La Réunion reached 1.5% at the height of the 2005–2006 outbreaks, highlighting the need for development of safety measures to prevent transfusion-transmitted infections. We describe successful inactivation of CHIKV in human platelets and plasma using photochemical treatment with amotosalen and long wavelength UVA illumination. Platelet components in additive solution and plasma units were inoculated with two different strains of high titer CHIKV stock (6.0–8.0 logs/mL), and then treated with amotosalen and exposure to 1.0–3.0 J/cm² UVA. Based on in vitro assays of infectious virus pre- and post-treatment to identify endpoint dilutions where virus was not detectable, mean viral titers could effectively be reduced by > 6.4 ± 0.6 log[subscript 10] TCID[subscript 50]/mL in platelets and ≥ 7.6 ± 1.4 logs in plasma, indicating this treatment has the capacity to prevent CHIKV transmission in human blood components collected from infected donors in or traveling from areas of CHIKV transmission

Biological Control Strategies for Mosquito Vectors of Arboviruses

Citation: Huang, Y.-J.S.; Higgs, S.; Vanlandingham, D.L. Biological Control Strategies for Mosquito Vectors of Arboviruses. Insects 2017, 8, 21.Historically, biological control utilizes predatory species and pathogenic microorganisms to reduce the population of mosquitoes as disease vectors. This is particularly important for the control of mosquito-borne arboviruses, which normally do not have specific antiviral therapies available. Although development of resistance is likely, the advantages of biological control are that the resources used are typically biodegradable and ecologically friendly. Over the past decade, the advancement of molecular biology has enabled optimization by the manipulation of genetic materials associated with biological control agents. Two significant advancements are the discovery of cytoplasmic incompatibility induced by Wolbachia bacteria, which has enhanced replacement programs, and the introduction of dominant lethal genes into local mosquito populations through the release of genetically modified mosquitoes. As various arboviruses continue to be significant public health threats, biological control strategies have evolved to be more diverse and become critical tools to reduce the disease burden of arboviruses

Anopheles gambiae heat shock protein cognate 70B impedes o'nyong-nyong virus replication

Background Phylogenetic and functional analysis was conducted on an Anopheles gambiae gene, ENSANGG00000017398. Based on phylogenetic analysis, this gene belongs to the same lineage as Heat shock protein cognate 70-4 (Hsc70-4) in Drosophila. Accordingly, we propose to name this gene Heat shock protein cognate 70B (HSC70B). We previously reported that expression of HSC70B and other genes including elongation factor-1α (EF-1α) and the agglutinin attachment subunit (agglutinin) were up-regulated in o'nyong-nyong virus (ONNV)-infected female An. gambiae. Double-stranded RNA interferences have been applied to further investigate HSC70B, EF-1α and the agglutinin functions in ONNV replication in An. gambiae. Results Among these three RNAi silenced genes, only dsRNAs of HSC70B (dsHSC70B) promoted ONNV replication in adult An. gambiae compared to the control mosquitoes that were co-injected with ONNV and dsRNA of β-galactosidase (dsβ-gal). ONNV titers from mosquitoes co-injected with dsHSC70B were about 9-fold higher at 6 days post-injection (d.p.i.) as compared to the control mosquitoes. By using ONNV tagged with enhanced green fluorescent protein (ONNV-eGFP), co-injection of ONNV-eGFP with dsHSC70B also showed approximately 2 ~ 3-fold higher GFP expression rates than the controls in the head, thorax, and abdomen of the mosquito. Furthermore, co-injection of ONNV with dsHSC70B significantly reduced the lifespan of adult mosquitoes as compared with the control, co-injection of ONNV with dsβ-gal treated mosquitoes. Conclusion These results indicate that HSC70B plays important roles in homeostasis and suppression of ONNV replication in the vector, An. gambiae. Biological implications of these findings are that while mosquitoes allow ONNV to replicate in them, they also check viral titers so that ONNV infection will result in no harmful effect on mosquitoes. Therefore, mosquitoes can function as vectors of ONNV transmission to humans while ONNV infection in An. gambiae remains asymptomatic.We wish to thank Dr. K. E. Olson and B. D. Foy for his kind gift of infectious clone pONNic-Foy. This research would not have been possible without the assistance of Dr. Mabel Berois with helpful guide. This project was supported by grants R01-AI44273 from NIH/NIAID to F.H.C. D.L.V. was supported by NIH T32 A10753

Infection of myofibers contributes to increased pathogenicity during infection with an epidemic strain of chikungunya virus

Chikungunya virus (CHIKV) is an alphavirus transmitted by mosquitoes that is known to cause severe arthritis and myositis in affected patients. The ongoing epidemic began in eastern Africa in 2004 and then spread to islands of the Indian Ocean, India, and Southeast Asia, ultimately afflicting millions. During this outbreak, more severe disease manifestations, including fatalities, have been documented. The reasons for this change in pathogenesis are multifactorial but likely include mutations that have arisen in the viral genome which could alter disease pathogenesis. To test this hypothesis, we used a murine model of CHIKV to compare the disease pathogeneses of two recombinant strains of CHIKV, the first derived from the La Reunion outbreak in 2006 (LR2006 OPY1) and the second isolated from Senegal in 1983 (37997). While the two strains exhibited similar growth in mammalian cells in vitro, we observed more severe clinical disease and pathology in mice infected with the LR2006 OPY1 strain of CHIKV, which included prolonged viremia and elevated viral titers and persistence in the muscle, resulting in devastating myonecrosis. Both CHIKV strains infected connective tissue fibroblasts of the muscle, but only the LR2006 OPY1 strain replicated within myofibers in vivo, despite similar growth of the two strains in these cell types in vitro. However, when the 37997 strain was administered directly into muscle, myofiber infection was comparable to that in LR2006 OPY1-infected mice. These results indicate that differences in the ability of the strain of CHIKV to establish infection in myofibers may contribute to the increased disease severity. IMPORTANCE CHIKV is an emerging pathogen that causes significant morbidity. Little is known about the pathogenesis of the disease, and this study suggests that the ability of a recent epidemic strain to infect myofibers results in increased disease severity. Better understanding of how CHIKV causes disease contributes to the ultimate goal of creating therapeutics to alleviate the impact of this debilitating virus

Culex tarsalis is a competent vector species for Cache Valley virus

Background: Cache Valley virus (CVV) is a mosquito-borne orthobunyavirus endemic in North America. The virus is an important agricultural pathogen leading to abortion and embryonic lethality in ruminant species, especially sheep. The importance of CVV in human public health has recently increased because of the report of severe neurotropic diseases. However, mosquito species responsible for transmission of the virus to humans remain to be determined. In this study, vector competence of three Culex species mosquitoes of public health importance, Culex pipiens, Cx. tarsalis and Cx. quinquefasciatus, was determined in order to identify potential bridge vector species responsible for the transmission of CVV from viremic vertebrate hosts to humans. Results: Variation of susceptibility to CVV was observed among selected Culex species mosquitoes tested in this study. Per os infection resulted in the establishment of infection and dissemination in Culex tarsalis, whereas Cx. pipiens and Cx. quinquefasciatus were highly refractory to CVV. Detection of viral RNA in saliva collected from infected Cx. tarsalis provided evidence supporting its role as a competent vector. Conclusions: Our study provided further understanding of the transmission cycles of CVV and identifies Cx. tarsalis as a competent vector

Flavivirus-Mosquito Interactions

Citation: Huang, Y.-J.S.; Higgs, S.; Horne, K.M.; Vanlandingham, D.L. Flavivirus-Mosquito Interactions. Viruses 2014, 6, 4703-4730.The Flavivirus genus is in the family Flaviviridae and is comprised of more than 70 viruses. These viruses have a broad geographic range, circulating on every continent except Antarctica. Mosquito-borne flaviviruses, such as yellow fever virus, dengue virus serotypes 1–4, Japanese encephalitis virus, and West Nile virus are responsible for significant human morbidity and mortality in affected regions. This review focuses on what is known about flavivirus-mosquito interactions and presents key data collected from the field and laboratory-based molecular and ultrastructural evaluations

Limited evolution of West Nile virus has occurred during its southwesterly spread in the United States

AbstractAnalysis of partial nucleotide sequences of nine West Nile virus strains isolated in southeast Texas during June–August 2002 revealed a maximum of 0.35% nucleotide variation from a New York 1999 strain. Two sequence subtypes were identified that differed from each other by approximately 0.5%, suggesting multiple introductions of virus to this area. Analysis of sequences from cloned PCR products for one strain revealed up to 0.6% divergence from the consensus sequence at the subpopulation level. The presence of unique patterns of small numbers of mutations in North American West Nile strains studied to date may suggest the absence of a strong selective pressure to drive the emergence of dominant variants

Antiviral activity of silymarin against chikungunya virus

Citation: Lani, R., Hassandarvish, P., Chiam, C. W., Moghaddam, E., Chu, J. J. H., Rausalu, K., . . . Zandi, K. (2015). Antiviral activity of silymarin against chikungunya virus. Scientific Reports, 5, 10. doi:10.1038/srep11421The mosquito-borne chikungunya virus (CHIKV) causes chikungunya fever, with clinical presentations such as severe back and small joint pain, and debilitating arthritis associated with crippling pains that persist for weeks and even years. Although there are several studies to evaluate the efficacy of drugs against CHIKV, the treatment for chikungunya fever is mainly symptom-based and no effective licensed vaccine or antiviral are available. Here, we investigated the antiviral activity of three types of flavonoids against CHIKV in vitro replication. Three compounds: silymarin, quercetin and kaempferol were evaluated for their in vitro antiviral activities against CHIKV using a CHIKV replicon cell line and clinical isolate of CHIKV of Central/East African genotype. A cytopathic effect inhibition assay was used to determine their activities on CHIKV viral replication and quantitative reverse transcription PCR was used to calculate virus yield. Antiviral activity of effective compound was further investigated by evaluation of CHIKV protein expression using western blotting for CHIKV nsP1, nsP3, and E2E1 proteins. Briefly, silymarin exhibited significant antiviral activity against CHIKV, reducing both CHIKV replication efficiency and down-regulating production of viral proteins involved in replication. This study may have important consequence for broaden the chance of getting the effective antiviral for CHIKV infection