Protective immunity by an engineered DNA vaccine for Mayaro virus.

Mayaro virus (MAYV) of the genus alphavirus is a mosquito-transmitted emerging infectious disease that causes an acute febrile illness, rash, headaches, and nausea that may turn into incapacitating, persistent arthralgias in some victims. Since its discovery in Trinidad in 1954, cases of MAYV infection have largely been confined there and to the northern countries of South America, but recently, MAYV cases have been reported in some island nations in the Caribbean Sea. Accompanying these reports is evidence that new vectors, including Aedes spp. mosquitos, recently implicated in the global spread of Zika and chikungunya viruses, are competent for MAYV transmission, which, if true, could facilitate the spread of MAYV beyond its current range. Despite its status as an emerging virus, there are no licensed vaccines to prevent MAYV infection nor therapeutics to treat it. Here, we describe the development and testing of a novel DNA vaccine, scMAYV-E, that encodes a synthetically-designed consensus MAYV envelope sequence. In vivo electroporation-enhanced immunization of mice with this vaccine induced potent humoral responses including neutralizing antibodies as well as robust T-cell responses to multiple epitopes in the MAYV envelope. Importantly, these scMAYV-E-induced immune responses protected susceptible mice from morbidity and mortality following a MAYV challenge.

ICTV Virus Taxonomy Profile: Togaviridae.

The Togaviridae is a family of small, enveloped viruses with single-stranded, positive-sense RNA genomes of 10-12 kb. Within the family, the genus Alphavirus includes a large number of diverse species, while the genus Rubivirus includes the single species Rubella virus. Most alphaviruses are mosquito-borne and are pathogenic in their vertebrate hosts. Many are important human and veterinary pathogens (e.g. chikungunya virus and eastern equine encephalitis virus). Rubella virus is transmitted by respiratory routes among humans. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the taxonomy of the Togaviridae, which is available at www.ictv.global/report/togaviridae.

Insect-Specific Viruses: A Historical Overview and Recent Developments.

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.

Mayaro fever virus, Brazilian Amazon.

In February 2008, a Mayaro fever virus (MAYV) outbreak occurred in a settlement in Santa Barbara municipality, northern Brazil. Patients had rash, fever, and severe arthralgia lasting up to 7 days. Immunoglobulin M against MAYV was detected by ELISA in 36 persons; 3 MAYV isolates sequenced were characterized as genotype D.

Phylogeographical structure and evolutionary history of two Buggy Creek virus lineages in the western Great Plains of North America.

Buggy Creek virus (BCRV) is an unusual arbovirus within the western equine encephalitis complex of alphaviruses. Associated with cimicid swallow bugs (Oeciacus vicarius) as its vector and the cliff swallow (Petrochelidon pyrrhonota) and house sparrow (Passer domesticus) as its amplifying hosts, this virus is found primarily in the western Great Plains of North America at spatially discrete swallow nesting colonies. For 342 isolates collected in Oklahoma, Nebraska, Colorado and North Dakota, from 1974 to 2007, we sequenced a 2076 bp region of the 26S subgenomic RNA structural glycoprotein coding region, and analysed phylogenetic relationships, rates of evolution, demographical histories and temporal genetic structure of the two BCRV lineages found in the Great Plains. The two lineages showed distinct phylogeographical structure: one lineage was found in the southern Great Plains and the other in the northern Great Plains, and both occurred in Nebraska and Colorado. Within each lineage, there was additional latitudinal division into three distinct sublineages. One lineage is showing a long-term population decline. In comparing sequences taken from the same sites 8-30 years apart, in one case one lineage had been replaced by the other, and in the other cases there was little evidence of the same haplotypes persisting over time. The evolutionary rate of BCRV is in the order of 1.6-3.6x10(-4) substitutions per site per year, similar to that estimated for other temperate-latitude alphaviruses. The phylogeography and evolution of BCRV could be better understood once we determine the nature of the ecological differences between the lineages.

Haemorrhagic smolt syndrome (HSS) in Norway: pathology and associated virus-like particles.

Atlantic salmon Salmo salar pre-smolt, smolt and post-smolt, with clinical signs of haemorrhagic smolt syndrome (HSS) have been found in several locations along the Norwegian coast (Rogaland to Troms). Affected fish had pale gills and bleeding at the fin bases, but seemed to be in good physical condition with no obvious weight loss. The internal organs and body cavity showed distinct bleedings. Petechiae were found on the gastrointestinal tract, swim bladder and peritoneum, visceral adipose tissue, heart and somatic musculature. The liver was bright yellow and sometimes mottled with petechiae and ecchymoses. Acitic fluid was found in the visceral cavity and fluid was also present in the pericardial cavity. Histological examination revealed haemorrhage in most organs. The glomeruli were degenerated and the renal tubules were filled with erythrocytes. The aims of this study were to describe the pathology and discover, if possible, the aetiology of the HSS. Tissues were collected for light and transmission electron microscopy (TEM), immunofluorescence (IFAT), reverse transcription (RT)-PCR diagnostics (screening for infectious salmon anaemia virus [ISAV], viral haemorrhagic septicaemia virus [VHSV], salmon pancreas disease virus [SPDV], sleeping disease virus [SDV] and infectious haematopoetic necrosis virus [IHNV]), and tissue homogenates (heart, liver, kidney and spleen) were sterile-filtered and inoculated into cell cultures. Homogenates made from several tissues were also injected intraperitoneally into salmon and rainbow trout Oncorhynchus mykiss. The diagnostic tests revealed no consistent findings of any pathogens, with the exception of TEM which showed 2 types of virus-like particles: Type I was 50 to 60 nm in diameter and Type II about 50 nm in diameter. These virus-like particles were found in salmon from all farms affected by HSS and screened by TEM. Several different cells, blood vessel endothelial cells, endocardial cells, heart myofibres, and leukocytes were associated with the 2 virus-like particles. The Type I particle seems to be an infectious pancreatic necrosis (IPN)-like virus, while (based on the number of target cells, particle morphology, budding and uptake into target cells) Type II particle could be a togavirus.

The Coronaviridae now comprises two genera, coronavirus and torovirus: report of the Coronaviridae Study Group.

At the April 1992, mid-term meeting of the International Committee on Taxonomy of Viruses (ICTV) a proposal from the Coronaviridae Study Group (CSG) to include the torovirus genus in the Coronaviridae was accepted. Following another proposal, the arterivirus genus was removed from the Togaviridae but not assigned to another family. The arteriviruses have some features in common with the Coronaviridae but also have major differences. After much debate, culminating in September 1992, it was decided that the CSG would not recommend inclusion of arterivirus in the Coronaviridae. It was agreed that (a) the nomenclature used for coronavirus genes, mRNAs and polypeptides (Cavanagh et al., 1990) should be used for toroviruses, (b) that the small (about 100 amino acids) membrane-associated protein, which is distinct from the integral membrane glycoprotein M, associated with virions of infectious bronchitis (Liu & Inglis, 1991) and transmissible gastroenteritis (Godet et al., 1992) coronaviruses would be referred to by the acronym sM (lower case 's') and (c) that 'pol' (polymerase) should be used as a working term for gene 1, which comprises open reading frames (ORFs) 1a and 1b in both genera of the Coronaviridae.

[Hepatitis C virus]. / Le virus de l'hépatite C.

Hepatitis C Virus, major causative agent of parenterally transmitted non-A non-B hepatitis was identified by Choo et al. in 1988 using molecular biology technologies. This virus contains a positive stranded RNA genome, it has been shown to have a small diameter. These structure and properties suggest that HCV shares many features in common with Pestiviruses and Flaviviruses. After many years of research, two major objectives were reached: -the identification of viral genome and the main purified viral polypeptide derived from recombinant yeast. Major information were recently appearing about the nucleotide sequences of different isolates coming from US, Europe and Japan; -the preparation of specific tool (ELISA anti-HCV) for detection of circulating HCV antibodies.

Aetiological association of virus like particles with hepatitis C.

Isolation of virus-like particles from sera of anti-HCV positive patients and their ultrastructural characterization are reported. Particles were identified in sera of 5 out of 6 patients tested. Immunoelectron microscopy assay revealed small aggregates of viral particles. Size and morphological criteria suggest that these particles can be classified as Togaviridae.

Uso de células de Aedes albopictus C6/36 na propagaçäo e classificaçäo de arbovirus das famílias Togaviridae, Flaviviridae, Bunyaviridae e Rhabdoviridae / The use of Aedes albopictus C6/36 cells in the propagation and classification of arbovirus of the Togaviridae, Flaviviridae, Bunyaviridae and Rhabdoviridae families

Colônias de células de mosquito Aedes albopicus C6/36 foram infectadas com 23 arbovirus, sendo 19 destes existentes no Brasil, pertencentes às famílias Togavitidae, Flaviviridae, Bunyaviridae e Rhabdoviridae. A Replicaçäo viral foi detectada por imunofluorescência indireta com todos os vírus estudados enquanto que o efeito citopático foi observado durante a infecçäo por alguns deste. No teste de imunofluorescência indireta utilizou-se fluidos ascíticos imunes de camundongos, especificos para os vírus estudados. A replicaçäo viral caracterizada por grande produçäo de antígeno recomenda a utilizaçäo de células C6/36 na propagaçäo e em tentativas de isolamento desses arbovírus. A técnica de imunofluorescência ofereceu subsídios na classificaçäo e identificaçäo de vírus que replicam nestas células

[The use of Aedes albopictus C6/36 cells in the propagation and classification of arbovirus of the Togaviridae, Flaviviridae, Bunyaviridae and Rhabdoviridae families]. / Uso de células de Aedes albopictus C6/36 na propagação e classificação de arbovírus das famílias Togaviridae, Flaviviridae, Bunyaviridae e Rhabdoviridae.

C6/36 Aedes albopictus cells were infected with Brazilian arbovirus from the families Togaviridae, Flaviviridae, Bunyaviridae and Rhabdoviridae. Replication was obtained with all the studied viruses and cytopathic effect was observed with some. Viral antigen was assayed in C6/36 cell cultures for antigen was assayed in C6/36 cells by an indirect immunofluorescence test using specific mouse immune ascitic fluid. Antigen production was detected in C6/36 cells infected with all the studied viruses. The author recommends the inoculation of C6/36 cell cultures for isolation of virus from the four studied families. The immunofluorescence technique is an important tool for classification and identification of virus growing in C6/36 cells.

Togaviridae.

The family Togaviridae comprises four genera: Alphavirus (with 26 species), Rubivirus (one species), Pestivirus (three species), and Arterivirus (one species). The main characteristics of the member viruses are: (i) the virus particles are spherical, 50-70 nm in diameter, including an envelope with surface projections that incorporate two or three polypeptides, usually glycosylated; (ii) the nucleocapsid comprises a core protein and a single strand of positive-sense RNA, molecular weight about 4 X 10(6); where characterized, the RNA has an m7G 'cap' at the 5' end and is polyadenylated at the 3' end; (iii) maturation occurs by budding of spherical nucleocapsids 30-35 nm in diameter, with proven or presumed icosahedral symmetry, through cytoplasmic membranes. Where characterized, translation of structural proteins occurs on subgenomic messenger RNA(s); these appear to represent the 3' end of the genome. Nearly all alphavirus species are transmitted by mosquitoes. Transmission also occurs transovarially (Alphavirus) or transplacentally (Rubivirus and Pestivirus). Members of a genus are serologically related, but are not related to members of other genera.

[Numerical classification of viruses within families]. / Chislovaia klassifikatsiia virusov vnutri semeistv.

The possibility of using cluster analysis for allocation of viruses into groups having a taxonomic rank below the family was studied. As a result, a modified variant of cluster analysis is proposed which may be used for investigation of similarities and differences among viruses within individual families and formation of groups corresponding to those of a lower taxonomic rank than the family. The use of this modified variant of cluster analysis allowed the authors to distinguish groups in the majority of the families studied corresponding to ICTV genera. The data have been obtained suggesting the necessity of changing the taxonomic rank of some virus groups. The above studies have shown the possibility of developing numerical classification of viruses at the subfamily and genus levels, in other words, a single hierarchical numerical classification of viruses.

Electron microscopic observation of a newly isolated flavivirus-like virus from field-caught mosquitoes.

Of many unidentified virus strains which were isolated from field-caught mosquitoes by using C6/36 cells (a virus-sensitive clone of Aedes albopictus cells), three strains which formed small size plaques (SP virus) in C6/36 cells were investigated by electron microscopy. Although the SP virus strains did not react with antisera against known arboviruses in serological tests, they closely resembled flaviviruses in morphology. However, when they were compared to Japanese encephalitis (JE) virus, several differences in morphogenesis were observed. Proliferating membranous structures and electron-dense amorphous areas involving precursors of the virus were observed only in cells infected with the SP virus strains. Enlarged areas of endoplasmic reticulum containing mature virions were often observed adjacent to these structures. Since the SP virus strains were isolated from wild mosquitoes and multiplied only in mosquito cells, it seems appropriate to classify them as insect viruses which resemble togaviruses morphologically.

[Arboviruses - structure and classification (author's transl)]. / Arbovirus - structure et classification.

The larger, biologically defined, set of arboviruses contains sub-sets representative of a number of different taxons. Arboviruses classified on serological grounds into Groups A and B are now placed respectively into the genera alphavirus and flavivirus, which form part of the family Togaviridae. The recently defined family Bunyaviridae contains almost 200 different arboviruses, serologically divisible into at least 24 different serogroups. The family Reoviridae includes the genus orbivirus which covers at least 17 serological groups, and the family Rhabdoviridae is another major family which contains a significant number of arboviruses. Outside these four families individual arboviruses are placed are placed in the families Iridoviridae, Poxviridae, Picornaviridae and Coronaviridae, but a least 50 arbovirueses remain unclassified.