Detection of Toscana virus-specific immunoglobulins G and M by an enzyme-linked immunosorbent assay based on recombinant viral nucleoprotein.
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An enzyme-linked immunosorbent assay (ELISA) based on the recombinant Toscana virus nucleoprotein (rN) has been developed. Its sensitivity and specificity for the detection of virus-specific immunoglobulins G and M in human sera were similar to those of the ELISA that is based on an antigen extracted from infected mouse brain and that is routinely used for serodiagnosis. (+info)
Seroprevalence of West Nile, Rift Valley, and sandfly arboviruses in Hashimiah, Jordan.
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We conducted a serosurvey among patients of a health center in Hashimiah, a Jordanian town of 30,000 inhabitants located near a wastewater treatment plant and its effluent channel. Serum samples from 261 patients >/=5 years of age were assessed for immunoglobulin G (IgG) and IgM antibodies against West Nile, sandfly Sicilian, sandfly Naples, and Rift Valley viruses; the seroprevalence of IgG antibodies was 8%, 47%, 30%, and 0%, respectively. Female participants were more likely to have been infected than male. Persons living within 2 km of the treatment plant were more likely to have been infected with West Nile (p=0.016) and sandfly Sicilian (p=0.010) viruses. Raising domestic animals within the house was a risk factor for sandfly Sicilian (p=0.003) but not for sandfly Naples virus (p=0.148). All serum samples were negative for IgM antibodies against the tested viruses. Our study is the first documentation of West Nile and sandfly viruses in Jordan and calls attention to the possible health hazards of living close to wastewater treatment plants and their effluent channels. (+info)
Poised for contagion: evolutionary origins of the infectious abilities of invertebrate retroviruses.
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Phylogenetic analyses suggest that long-terminal repeat (LTR) bearing retrotransposable elements can acquire additional open-reading frames that can enable them to mediate infection. Whereas this process is best documented in the origin of the vertebrate retroviruses and their acquisition of an envelope (env) gene, similar independent events may have occurred in insects, nematodes, and plants. The origins of env-like genes are unclear, and are often masked by the antiquity of the original acquisitions and by their rapid rate of evolution. In this report, we present evidence that in three other possible transitions of LTR retrotransposons to retroviruses, an envelope-like gene was acquired from a viral source. First, the gypsy and related LTR retrotransposable elements (the insect errantiviruses) have acquired their envelope-like gene from a class of insect baculoviruses (double-stranded DNA viruses with no RNA stage). Second, the Cer retroviruses in the Caenorhabditis elegans genome acquired their envelope gene from a Phleboviral (single ambisense-stranded RNA viruses) source. Third, the Tas retroviral envelope (Ascaris lumricoides) may have been obtained from Herpesviridae (double-stranded DNA viruses, no RNA stage). These represent the only cases in which the env gene of a retrovirus has been traced back to its original source. This has implications for the evolutionary history of retroviruses as well as for the potential ability of all LTR-retrotransposable elements to become infectious agents. (+info)
Encephalitis without meningitis due to sandfly fever virus serotype toscana.
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The role of Toscana (TOS) virus in producing encephalitis without meningitis is uncertain. We studied 2 cases of TOS virus encephalitis without meningitis by means of nested polymerase chain reaction assay and DNA sequencing. Findings confirm that TOS virus may directly cause encephalitis and suggest the usefulness of DNA sequencing in investigating relationships between TOS virus molecular patterns and the spectrum of neurological involvement. (+info)
Characterization of the Golgi retention motif of Rift Valley fever virus G(N) glycoprotein.
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As Rift Valley fever (RVF) virus, and probably all members of the family Bunyaviridae, matures in the Golgi apparatus, the targeting of the virus glycoproteins to the Golgi apparatus plays a pivotal role in the virus replication cycle. No consensus Golgi localization motif appears to be shared among the glycoproteins of these viruses. The viruses of the family Bunyaviridae synthesize their glycoproteins, G(N) and G(C), as a polyprotein. The Golgi localization signal of RVF virus has been shown to reside within the G(N) protein by use of a plasmid-based transient expression system to synthesize individual G(N) and G(C) proteins. While the distribution of individually expressed G(N) significantly overlaps with cellular Golgi proteins such as beta-COP and GS-28, G(C) expressed in the absence of G(N) localizes to the endoplasmic reticulum. Further analysis of expressed G(N) truncated proteins and green fluorescent protein/G(N) chimeric proteins demonstrated that the RVF virus Golgi localization signal mapped to a 48-amino-acid region of G(N) encompassing the 20-amino-acid transmembrane domain and the adjacent 28 amino acids of the cytosolic tail. (+info)
Phylogenetic relationships among members of the genus Phlebovirus (Bunyaviridae) based on partial M segment sequence analyses.
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Viruses in the Phlebovirus genus of the family Bunyaviridae cause clinical syndromes ranging from a short, self-limiting febrile illness to fatal haemorrhagic fever. The genus currently consists of 68 antigenically distinct virus serotypes, most of which have not been genetically characterized. RT-PCR with four 'cocktail' primers was performed to amplify a region of the M segment of the genome of 24 phleboviruses included in the sandfly fever Naples, sandfly fever Sicilian and Punta Toro serocomplexes. Partial M segment sequences were successfully obtained and phylogenetic analysis was performed. The three resultant genotypic lineages were consistent with serological data. The sequence divergences were 27.6 % (nucleotide) and 25.7 % (amino acid) within the Sicilian serocomplex, 33.7 % (nucleotide) and 34.4 % (amino acid) within the Naples serocomplex and 35.6 % (nucleotide) and 37.5 % (amino acid) within the Punta Toro serocomplex. Overall, the diversities among viruses of Sicilian, Naples and Punta Toro serocomplexes were 48.2 % and 57.6 % at the nucleotide and amino acid levels, respectively. This high genetic divergence may explain the difficulties in designing a consensus primer pair for the amplification of all the phleboviruses using RT-PCR. It also suggests that infection with one genotype may not completely immunize against infection with all other genotypes in a given serocomplex. These findings have implications for potential vaccine development and may help explain clinical reports of multiple episodes of sandfly fever in the same individual. (+info)
Induction of severe disease in hamsters by two sandfly fever group viruses, Punta toro and Gabek Forest (Phlebovirus, Bunyaviridae), similar to that caused by Rift Valley fever virus.
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Adult golden hamsters inoculated subcutaneously with either of two sandfly fever group viruses, Punta Toro and Gabek Forest (Phlebovirus, Bunyaviridae), developed a fulminating fatal illness characterized by hepatic and splenic necrosis and interstitial pneumonitis. Most animals died within three days after infection; this was accompanied by high levels of viremia. Necropsy and histopathologic examination of the infected animals revealed pathologic changes involving multiple organs that resembled those described in Rift Valley fever. These two hamster-phlebovirus systems may serve as alternative animal models for Rift Valley fever and should be useful in studying the pathogenesis of severe phlebovirus infection and for testing potential therapeutic agents. (+info)
Association of the nonstructural protein NSs of Uukuniemi virus with the 40S ribosomal subunit.
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The small RNA segment (S segment) of Uukuniemi (UUK) virus encodes two proteins, the nucleocapsid protein (N) and a nonstructural protein (NSs), by an ambisense strategy. The function of NSs has not been elucidated for any of the bunyaviruses expressing this protein. We have now expressed the N and NSs proteins in Sf9 insect cells by using the baculovirus expression system. High yields of both proteins were obtained. A monospecific antibody was raised against gel-purified NSs and used to study the synthesis and localization of the protein in UUK virus-infected BHK21 cells. While the N protein was detected as early as 4 h postinfection (p.i.), NSs was identified only after 8 h p.i. Both proteins were still synthesized at high levels at 24 h p.i. The half-life of NSs was about 1.5 h, while that of the N protein was several hours. Sucrose gradient fractionation of [35S]methionine-labeled detergent-solubilized extracts of infected BHK21 cells indicated that NSs was firmly associated with the 40S ribosomal subunit. This association took place shortly after translation and was partially resistant to 1 M NaCl. NSs expressed by using the T7 vaccinia virus expression system, as well as in vitro-translated NSs, was also associated with the 40S subunit. In contrast, in vitro-translated N protein was found on top of the gradient. Immunolocalization of NSs, in UUK virus-infected cells, by using an affinity-purified antibody showed a granular cytoplasmic staining. A very similar pattern was seen for cells expressing NSs from a cDNA copy by using a vaccinia virus expression system. No staining was observed in the nuclei in either case. Furthermore, NSs was found neither in virions nor in nucleocapsids isolated from infected cells. In vivo labeling with 32Pi indicated that NSs is not phosphorylated. The possible function of NSs is discussed in light of these results. (+info)