RESUMEN

The Bunyavirales order is the largest grouping of RNA viruses, comprising emerging and re-emerging human, plant and animal pathogens. Bunyaviruses have a global distribution and many members of the order are transmitted by arthropods. They have evolved a plethora of mechanisms to manipulate the regulatory processes of the infected cell to facilitate their own replicative cycle, in hosts of disparate phylogenies. Interest in virus-vector interactions is growing rapidly. However, current understanding of tick-borne bunyavirus cellular interaction is heavily biased to studies conducted in mammalian systems. In this short review, we summarise current understandings of how tick-borne bunyaviruses utilise major cellular pathways (innate immunity, apoptosis and RNAi responses) in mammalian or tick cells to facilitate virus replication.

Asunto(s)

Infecciones por Bunyaviridae , Bunyaviridae , Orthobunyavirus , Enfermedades por Picaduras de Garrapatas , Garrapatas , Animales , Humanos , Orthobunyavirus/genética , Interacciones Microbiota-Huesped , Bunyaviridae/fisiología , Mamíferos

RESUMEN

Bunyaviruses represent the largest group of RNA viruses and are the causative agent of a variety of febrile and hemorrhagic illnesses. Originally characterized as a single serotype in Africa, the number of described bunyaviruses now exceeds over 500, with its presence detected around the world. These predominantly tri-segmented, single-stranded RNA viruses are transmitted primarily through arthropod and rodent vectors and can infect a wide variety of animals and plants. Although encoding for a small number of proteins, these viruses can inflict potentially fatal disease outcomes and have even developed strategies to suppress the innate antiviral immune mechanisms of the infected host. This short review will attempt to provide an overall description of the order Bunyavirales, describing the mechanisms behind their infection, replication, and their evasion of the host immune response. Furthermore, the historical context of these viruses will be presented, starting from their original discovery almost 80 years ago to the most recent research pertaining to viral replication and host immune response.

Asunto(s)

Bunyaviridae , Orthobunyavirus , Virus ARN , Animales , Bunyaviridae/fisiología , Replicación Viral , Antivirales

RESUMEN

A key step during the entry of enveloped viruses into cells is the merger of viral and cell lipid bilayers. This process is driven by a dedicated membrane fusion protein (MFP) present at the virion surface, which undergoes a membrane-fusogenic conformational change triggered by interactions with the target cell. Viral MFPs have been extensively studied structurally, and are divided into three classes depending on their three-dimensional fold. Because MFPs of the same class are found in otherwise unrelated viruses, their intra-class structural homology indicates horizontal gene exchange. We focus this review on the class II fusion machinery, which is composed of two glycoproteins that associate as heterodimers. They fold together in the ER of infected cells such that the MFP adopts a conformation primed to react to specific clues only upon contact with a target cell, avoiding premature fusion in the producer cell. We show that, despite having diverged in their 3D fold during evolution much more than the actual MFP, the class II accompanying proteins (AP) also derive from a distant common ancestor, displaying an invariant core formed by a ß-ribbon and a C-terminal immunoglobulin-like domain playing different functional roles-heterotypic interactions with the MFP, and homotypic AP/AP contacts to form spikes, respectively. Our analysis shows that class II APs are easily identifiable with modern structural prediction algorithms, providing useful information in devising immunogens for vaccine design.

Asunto(s)

Alphavirus/fisiología , Bunyaviridae/fisiología , Genoma Viral/genética , Glicoproteínas/química , Proteínas Virales de Fusión/química , Internalización del Virus , Alphavirus/genética , Animales , Evolución Biológica , Bunyaviridae/genética , Glicoproteínas/metabolismo , Humanos , Membrana Dobles de Lípidos/metabolismo , Modelos Estructurales , Multimerización de Proteína , Proteínas Virales de Fusión/metabolismo , Virión

RESUMEN

The Bunyavirales order comprises more than 500 viruses (generally defined as bunyaviruses) classified into 12 families. Some of these are highly pathogenic viruses infecting different hosts, including humans, mammals, reptiles, arthropods, birds, and/or plants. Host cell sensing of infection activates the innate immune system that aims at inhibiting viral replication and propagation. Upon recognition of pathogen-associated molecular patterns (PAMPs) by cellular pattern recognition receptors (PRRs), numerous signaling cascades are activated, leading to the production of interferons (IFNs). IFNs act in an autocrine and paracrine manner to establish an antiviral state by inducing the expression of hundreds of IFN-stimulated genes (ISGs). Some of these ISGs are known to restrict bunyavirus infection. Along with other constitutively expressed host cellular factors with antiviral activity, these proteins (hereafter referred to as "restriction factors") target different steps of the viral cycle, including viral entry, genome transcription and replication, and virion egress. In reaction to this, bunyaviruses have developed strategies to circumvent this antiviral response, by avoiding cellular recognition of PAMPs, inhibiting IFN production or interfering with the IFN-mediated response. Herein, we review the current knowledge on host cellular factors that were shown to restrict infections by bunyaviruses. Moreover, we focus on the strategies developed by bunyaviruses in order to escape the antiviral state developed by the infected cells.

Asunto(s)

Infecciones por Bunyaviridae/virología , Bunyaviridae/fisiología , Interacciones Huésped-Patógeno , Animales , Biomarcadores , Bunyaviridae/clasificación , Infecciones por Bunyaviridae/inmunología , Infecciones por Bunyaviridae/metabolismo , Genoma Viral , Genómica/métodos , Interacciones Huésped-Patógeno/genética , Interacciones Huésped-Patógeno/inmunología , Humanos , Tolerancia Inmunológica , Inmunidad Innata , Interferón Tipo I/metabolismo , Receptores de Reconocimiento de Patrones/metabolismo , Virión , Replicación Viral

RESUMEN

Many mosquito-borne viruses (arboviruses) are endemic in Africa, contributing to systemic and neurological infections in various geographical locations on the continent. While most arboviral infections do not lead to neuroinvasive diseases of the central nervous system, neurologic diseases caused by arboviruses include flaccid paralysis, meningitis, encephalitis, myelitis, encephalomyelitis, neuritis, and post-infectious autoimmune or memory disorders. Here we review endemic members of the Flaviviridae and Togaviridae families that cause neurologic infections, their neuropathogenesis and host neuroimmunological responses in Africa. We also discuss the potential for neuroimmune responses to aide in the development of new diagnostics and therapeutics, and current knowledge gaps to be addressed by arbovirus research.

Asunto(s)

Infecciones por Arbovirus/inmunología , Arbovirus/inmunología , Sistema Nervioso Central/inmunología , Encefalitis por Arbovirus/inmunología , África/epidemiología , Animales , Infecciones por Arbovirus/epidemiología , Infecciones por Arbovirus/virología , Arbovirus/clasificación , Arbovirus/fisiología , Bunyaviridae/inmunología , Bunyaviridae/fisiología , Sistema Nervioso Central/virología , Encefalitis por Arbovirus/epidemiología , Encefalitis por Arbovirus/virología , Epidemias , Flaviviridae/inmunología , Flaviviridae/fisiología , Humanos , Togaviridae/inmunología , Togaviridae/fisiología

RESUMEN

Ticks are the primary vector of arboviruses in temperate climates worldwide. They are both the vector of these pathogens to humans and an integral component of the viral sylvatic cycle. Understanding the tick-pathogen interaction provides information about the natural maintenance of these pathogens and informs the development of countermeasures against human infection. In this review, we discuss currently available information on tick-viral interactions within the broader scope of general tick immunology. While the tick immune response to several pathogens has been studied extensively, minimal work centres on responses to viral infection. This is largely due to the high pathogenicity of tick-borne viruses; this necessitates high-containment laboratories or low-pathogenicity substitute viruses. This has biased most research towards tick-borne flaviviruses. More work is required to fully understand the role of tick-virus interaction in sylvatic cycling and transmission of diverse tick-borne viruses.

Asunto(s)

Garrapatas/fisiología , Fenómenos Fisiológicos de los Virus/inmunología , Virus/clasificación , Animales , Bunyaviridae/fisiología , Flaviviridae/fisiología , Humanos , Inmunidad Innata/fisiología , Orthomyxoviridae/fisiología , Interferencia de ARN/fisiología , Reoviridae/fisiología , Garrapatas/genética , Garrapatas/inmunología , Fenómenos Fisiológicos de los Virus/genética

RESUMEN

The majority of plant-infecting viruses are transmitted by arthropod vectors that deliver them directly into a living plant cell. There are diverse mechanisms of transmission ranging from direct binding to the insect stylet (non-persistent transmission) to persistent-propagative transmission in which the virus replicates in the insect vector. Despite this diversity in interactions, most arthropods that serve as efficient vectors have feeding strategies that enable them to deliver the virus into the plant cell without extensive damage to the plant and thus effectively inoculate the plant. As such, the primary virus entry mechanism for plant viruses is mediated by the biological vector. Remarkably, viruses that are transmitted in a propagative manner (bunyaviruses, rhabdoviruses, and reoviruses) have developed an ability to replicate in hosts from two kingdoms. Viruses in the order Bunyavirales are of emerging importance and with the advent of new sequencing technologies, we are getting unprecedented glimpses into the diversity of these viruses. Plant-infecting bunyaviruses are transmitted in a persistent, propagative manner must enter two unique types of host cells, plant and insect. In the insect phase of the virus life cycle, the propagative viruses likely use typical cellular entry strategies to traverse cell membranes. In this review, we highlight the transmission and entry strategies of three genera of plant-infecting bunyaviruses: orthotospoviruses, tenuiviruses, and emaraviruses.

Asunto(s)

Vectores Artrópodos/virología , Bunyaviridae/fisiología , Conducta Alimentaria , Plantas/parasitología , Plantas/virología , Internalización del Virus , Animales

RESUMEN

Ti ringspot is an emerging foliar disease of the ti plant (Cordyline fruticosa) in Hawaii that is quickly spreading throughout the islands. Symptoms include small chlorotic ringspots on leaves that often coalesce to form larger lesions. Although several virus species have been discovered in symptomatic plants, none have been associated with these symptoms. Here, we report and characterize a novel virus closely associated with ti ringspot symptoms in Hawaii. The presence of double membrane bodies approximately 85 nm in diameter in symptomatic cells and sequence analyses of five genomic RNA segments obtained by high-throughput sequencing indicate that this virus is most closely related to members of the plant virus genus Emaravirus. Phylogenetic and sequence homology analyses place this virus on a distinct clade within the Emaravirus genus along with High Plains wheat mosaic emaravirus, blue palo verde broom virus, and Raspberry leaf blotch emaravirus. Sequence identity values with taxonomically relevant proteins indicate that this represents a new virus species, which we are tentatively naming ti ringspot-associated virus (TiRSaV). TiRSaV-specific reverse transcription PCR assays detected the virus in several experimental herbaceous host species following mechanical inoculation. TiRSaV was also detected in eriophyid mites collected from symptomatic ti plants, which may represent a putative arthropod vector of the virus.

Asunto(s)

Bunyaviridae , Cordyline , Animales , Bunyaviridae/clasificación , Bunyaviridae/genética , Bunyaviridae/fisiología , Cordyline/virología , Hawaii , Filogenia , Enfermedades de las Plantas/virología

RESUMEN

The order of Bunyavirales includes numerous (re)emerging viruses that collectively have a major impact on human and animal health worldwide. There are no vaccines for human use or antiviral drugs available to prevent or treat infections with any of these viruses. The development of efficacious and safe drugs and vaccines is a pressing matter. Ideally, such antivirals possess pan-bunyavirus antiviral activity, allowing the containment of every bunya-related threat. The fact that many bunyaviruses need to be handled in laboratories with biosafety level 3 or 4, the great variety of species and the frequent emergence of novel species complicate such efforts. We here examined the potential druggable targets of bunyaviruses, together with the level of conservation of their biological functions, structure, and genetic similarity by means of heatmap analysis. In the light of this, we revised the available models and tools currently available, pointing out directions for antiviral drug discovery.

Asunto(s)

Antivirales/aislamiento & purificación , Antivirales/farmacología , Bunyaviridae/fisiología , Bunyaviridae/ultraestructura , Vacunas Virales/inmunología , Vacunas Virales/aislamiento & purificación , Antivirales/uso terapéutico , Bunyaviridae/efectos de los fármacos , Bunyaviridae/inmunología , Humanos

RESUMEN

The order Bunyavirales comprises nine families of enveloped, negative-strand RNA viruses. Depending on the family and genus, bunyaviruses (i.e. now referring to all members of the Bunyavirales) contain genomes consisting of two to six segments. Each genome segment is encapsidated by multiple copies of the nucleocapsid (N) protein and one or a few molecules of the viral polymerase, forming so-called ribonucleoproteins (RNPs). Incorporation of RNPs into virions is mediated by the interaction of N with the cytoplasmic tails of the structural glycoproteins. Although some selectivity exists in the packaging of RNPs into virions, which seems to be driven by the 5' and 3'-untranslated regions of the genomic RNA segments, evidence is accumulating that bunyavirus genome packaging is a stochastic process.

Asunto(s)

Bunyaviridae/genética , Bunyaviridae/fisiología , Cápside/metabolismo , ARN Viral/genética , ARN Viral/metabolismo , Ensamble de Virus , Ribonucleoproteínas/metabolismo

RESUMEN

The Bunyavirales order is one of the largest groups of segmented negative-sense single-stranded RNA viruses, which includes many pathogenic strains that cause severe human diseases. The RNA segments of the bunyavirus genome are separately encapsidated by multiple copies of nucleoprotein (N), and both termini of each N-encapsidated genomic RNA segment bind to one copy of the viral L polymerase protein. The viral genomic RNA, N and L protein together form the ribonucleoprotein (RNP) complex that constitutes the molecular machinery for viral genome replication and transcription. Recently, breakthroughs have been achieved in understanding the architecture of bunyavirus RNPs with the determination of the atomic structures of the N and L proteins from various members of this order. In this review, we discuss the structures and functions of these bunyavirus RNP components, as well as viral genome replication and transcription mechanisms.

Asunto(s)

Infecciones por Bunyaviridae/virología , Bunyaviridae/fisiología , Ribonucleoproteínas/metabolismo , Transcripción Genética , Proteínas Virales/metabolismo , Replicación Viral , Animales , Bunyaviridae/genética , Regulación Viral de la Expresión Génica , Humanos , Ribonucleoproteínas/genética , Proteínas Virales/genética

RESUMEN

OBJECTIVES: To identify specific clinical and epidemiological parameters for clinical diagnosis of SFTSV infection with relatively higher accuracy. METHODS: 231 suspected cases of SFTS were reported by various medical institutions from 2011 to 2013 in Jiangsu Province, China. They were followed with SFTSV diagnosis tests and interview-administered questionnaires about demographic characteristics, clinical symptoms and epidemiological exposure factors. Univariate and multivariable logistic regression analysis were used to examine the diagnostic value of these parameters. RESULTS: SFTSV infection occurred only from April to October annually and usually in hilly areas of specific regions. Three prediction models of SFTSV infection were constructed. Model 3 with clinical and epidemiological parameters combined the benefits of both Model 1and Model 2, which was optimal and had an overall accuracy of 80.2%. Independent indicators for clinical diagnosis of SFTSV infection in Model 3 were as follows: lymphadenopathy (P = 0.01), leucopenia (P<0.01), age >50 years (P = 0.01), tick bites (P<0.01), raising domestic animals in the residential areas (P<0.01) and farming (P = 0.03). CONCLUSIONS: Our results show that using a combination of clinical and epidemiological parameters may be a feasible strategy to provide preliminary fast diagnosis as differentiating SFTSV infection from SFTS-like diseases, thus reducing the risk of misdiagnosis.

Asunto(s)

Infecciones por Bunyaviridae/diagnóstico , Tamizaje Masivo/métodos , Fiebre por Flebótomos/diagnóstico , Trombocitopenia/diagnóstico , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Agricultura , Animales , Bunyaviridae/fisiología , Infecciones por Bunyaviridae/epidemiología , Infecciones por Bunyaviridae/virología , China/epidemiología , Estudios de Factibilidad , Femenino , Geografía , Interacciones Huésped-Patógeno , Humanos , Modelos Logísticos , Masculino , Persona de Mediana Edad , Análisis Multivariante , Fiebre por Flebótomos/epidemiología , Fiebre por Flebótomos/virología , Encuestas y Cuestionarios , Síndrome , Trombocitopenia/epidemiología , Trombocitopenia/virología , Mordeduras de Garrapatas , Adulto Joven

RESUMEN

Arthropod-borne viruses (arboviruses) have in recent years become a tremendous global health concern resulting in substantial human morbidity and mortality. With the widespread utilization of molecular technologies such as next-generation sequencing and the advancement of bioinformatics tools, a new age of viral discovery has commenced. Many of the novel agents being discovered in recent years have been isolated from mosquitoes and exhibit a highly restricted host range. Strikingly, these insect-specific viruses have been found to be members of viral families traditionally associated with human arboviral pathogens, including but not limited to the families Flaviviridae, Togaviridae, Reoviridae, and Bunyaviridae. These agents therefore present novel opportunities in the fields of viral evolution and viral/vector interaction and have tremendous potential as agents for biocontrol of vectors and or viruses of medical importance.

Asunto(s)

Arbovirus/fisiología , Bunyaviridae/fisiología , Flaviviridae/fisiología , Virus de Insectos/fisiología , Insectos/virología , Reoviridae/fisiología , Togaviridae/fisiología , Animales , Arbovirus/clasificación , Arbovirus/patogenicidad , Evolución Biológica , Bunyaviridae/clasificación , Bunyaviridae/patogenicidad , Flaviviridae/clasificación , Flaviviridae/patogenicidad , Especificidad del Huésped , Humanos , Control de Insectos/métodos , Virus de Insectos/clasificación , Virus de Insectos/patogenicidad , Filogenia , Reoviridae/clasificación , Reoviridae/patogenicidad , Togaviridae/clasificación , Togaviridae/patogenicidad

RESUMEN

Bunyaviridae and Arenaviridae virus families include an important number of highly pathogenic viruses for humans. They are enveloped viruses with negative stranded RNA genomes divided into three (bunyaviruses) or two (arenaviruses) segments. Each genome segment is coated by the viral nucleoproteins (NPs) and the polymerase (L protein) to form a functional ribonucleoprotein (RNP) complex. The viral RNP provides the necessary context on which the L protein carries out the biosynthetic processes of RNA replication and gene transcription. Decades of research have provided a good understanding of the molecular processes underlying RNA synthesis, both RNA replication and gene transcription, for these two families of viruses. In this review we will provide a global view of the common features, as well as differences, of the molecular biology of Bunyaviridae and Arenaviridae. We will also describe structures of protein and protein-RNA complexes so far determined for these viral families, mainly focusing on the L protein, and discuss their implications for understanding the mechanisms of viral RNA replication and gene transcription within the architecture of viral RNPs, also taking into account the cellular context in which these processes occur. Finally, we will discuss the implications of these structural findings for the development of antiviral drugs to treat human diseases caused by members of the Bunyaviridae and Arenaviridae families.

Asunto(s)

Arenaviridae/genética , Arenaviridae/fisiología , Bunyaviridae/genética , Bunyaviridae/fisiología , Transcripción Genética , Proteínas Virales/metabolismo , Replicación Viral , Humanos , Nucleoproteínas/genética , Nucleoproteínas/metabolismo , ARN Polimerasa Dependiente del ARN/genética , ARN Polimerasa Dependiente del ARN/metabolismo , Proteínas Virales/genética

RESUMEN

The wheat curl mite, Aceria tosichella Keifer, (WCM) is a global pest of bread wheat that reduces yields significantly. In addition, WCM carries Wheat streak mosaic virus (WSMV, family Potyviridae, genus Tritimovirus), the most significant wheat virus in North America; High Plains wheat mosaic virus (HPWMoV, genus Emaravirus, formerly High plains virus); and Triticum mosaic virus (TriMV, family Potyviridae, genus Poacevirus). Viruses carried by WCM have reduced wheat yields throughout the U.S. Great Plains for >50 yr, with average yield losses of 2-3% and occasional yield losses of 7-10%. Acaricides are ineffective against WCM, and delayed planting of winter wheat is not feasible. Five wheat breeding lines containing Cmc4, a WCM resistance gene from Aegilops tauschii, and Wsm2, a WSMV resistance gene from wheat germplasm CO960293-2 were selected from the breeding process and assessed for phenotypic reaction to WCM feeding, population increase, and the degree of WSMV, HPWMoV, and TriMV infection. Experiments determined that all five lines are resistant to WCM biotype 1 feeding and population increase, and that two breeding lines contain resistance to WSMV, HPWMoV, and TriMV infection as well. These WCM-, WSMV-, HPWMoV-, and TriMV-resistant genotypes can be used improve management of wheat yield losses from WCM-virus complexes.

Asunto(s)

Antibiosis , Genotipo , Enfermedades de las Plantas/genética , Triticum/genética , Triticum/fisiología , Animales , Bunyaviridae/fisiología , Ácaros/fisiología , Enfermedades de las Plantas/virología , Potyviridae/fisiología , Triticum/virología

RESUMEN

Arthropod-borne viruses have a dual-host tropism and their transmission requires the infection of two disparate hosts, arthropods and vertebrates. Arboviruses occur in several RNA families that also contain viruses with a monotropism for either arthropods or vertebrates. The evolutionary origin of the dual-host tropism of arboviruses was recently identified for the family Bunyaviridae. Bunyaviruses were suggested to have evolved from viruses that are restricted to arthropods as hosts (arthropod-specific viruses). Additional findings of an immense genetic diversity of bunyaviruses in non-blood feeding arthropods support the hypothesis of an arthropod origin of vertebrate-pathogenic bunyaviruses.

Asunto(s)

Artrópodos/virología , Evolución Biológica , Bunyaviridae/fisiología , Animales , Infecciones por Bunyaviridae/virología

RESUMEN

In the last 25 years, the scientific and public attention paid to bunyaviruses has increased considerably.[...].

Asunto(s)

Bunyaviridae/fisiología , Bunyaviridae/patogenicidad , Interacciones Huésped-Patógeno , Virología/historia , Replicación Viral , Historia del Siglo XX , Historia del Siglo XXI , Humanos , Proteínas de la Matriz Viral , Virus

RESUMEN

Yellow ringspot is the only virus-like disease reported in redbud (Cercis spp.) with symptoms including vein clearing, chlorotic ringspots and oak-leaf pattern. A putative new emaravirus was present in all trees displaying typical yellow ringspot symptoms and the name redbud yellow ringspot associated virus is proposed. The virus genome is composed of at least five RNA segments. Two coding regions were studied to determine isolate diversity with results pointing to a homogeneous virus population. Host range was evaluated using graft transmission and by testing species found in close proximity to infected trees. Mite transmission with Aculops cercidis, the predominant species found in redbud trees in the epicenter of the disease, was evaluated but was not found to be a vector of the virus. Based on this study and the accumulated knowledge on emaravirus evolution we propose that speciation is allopatric, with vectors being a major component of the process.

Asunto(s)

Bunyaviridae/fisiología , Enfermedades de las Plantas/virología , Virus de Plantas/fisiología , Bunyaviridae/clasificación , Fabaceae/virología , Variación Genética , Genoma Viral , Secuenciación de Nucleótidos de Alto Rendimiento , Especificidad del Huésped , Fenotipo , Filogenia , Hojas de la Planta/virología , Virus de Plantas/clasificación

RESUMEN

The Bunyaviridae is the largest family of RNA viruses, with over 350 members worldwide. Several of these viruses cause severe diseases in livestock and humans. With an increasing number and frequency of outbreaks, bunyaviruses represent a growing threat to public health and agricultural productivity globally. Yet, the receptors, cellular factors and endocytic pathways used by these emerging pathogens to infect cells remain largely uncharacterized. The focus of this review is on the early steps of bunyavirus infection, from virus binding to penetration from endosomes. We address current knowledge and advances for members from each genus in the Bunyaviridae family regarding virus receptors, uptake, intracellular trafficking and fusion.

Asunto(s)

Bunyaviridae/fisiología , Interacciones Huésped-Patógeno , Acoplamiento Viral , Internalización del Virus , Animales , Humanos

RESUMEN

BACKGROUND: Some Palaearctic biting midge species (subgenus Avaritia) have been implicated as vectors of bluetongue virus in northern Europe. Separation of two species (C. obsoletus and C. scoticus) is considered difficult morphologically and, often, these female specimens are grouped in entomological studies. However, species-specific identification is desirable to understand their life history characteristics, assess their roles in disease transmission or measure their abundance during arboviral outbreaks. This study aims to investigate whether morphometric identification techniques can be applied to female C. obsoletus and C. scoticus individuals trapped at different geographical regions and time periods during the vector season. METHODS: C. obsoletus and C. scoticus were collected using light-suction traps from the UK, France and Spain, with two geographical locations sampled per country. A total of 759 C. obsoletus/C. scoticus individuals were identified using a molecular assay based on the cytochrome c oxidase subunit I gene. Fifteen morphometric measurements were taken from the head, wings and abdomen of slide-mounted specimens, and ratios calculated between these measurements. Multivariate analyses explored whether a combination of morphometric variables could lead to accurate species identification. Finally, Culicoides spp. collected in France at the start, middle and end of the adult vector season were compared, to determine whether seasonal variation exists in any of the morphometric measurements. RESULTS: The principal component analyses revealed that abdominal characteristics: length and width of the smaller and larger spermathecae, and the length of the chitinous plates and width between them, are the most reliable morphometric characteristics to differentiate between the species. Seasonal variation in the size of each species was observed for head and wing measurements, but not abdominal measurements. Geographical variation in the size of Culicoides spp. was also observed and is likely to be related to temperature at the trapping sites, with smaller individuals trapped at more southern latitudes. CONCLUSIONS: Our results suggest that female C. obsoletus and C. scoticus individuals can be separated under a stereomicroscope using abdominal measurements. Although we show the length and width of the spermathecae can be used to differentiate between the species, this can be time-consuming, so we recommend undertaking this using standardized subsampling of catches.

Asunto(s)

Virus de la Lengua Azul/fisiología , Bunyaviridae/fisiología , Ceratopogonidae/clasificación , Insectos Vectores/virología , Animales , Ceratopogonidae/genética , Ceratopogonidae/virología , Complejo IV de Transporte de Electrones/genética , Femenino , Regulación de la Expresión Génica , Masculino , Especificidad de la Especie