(1/24) The genome sequence of Yaba-like disease virus, a yatapoxvirus.

The genome sequence of Yaba-like disease virus (YLDV), an unclassified member of the yatapoxvirus genus, has been determined. Excluding the terminal hairpin loops, the YLDV genome is 144,575 bp in length and contains inverted terminal repeats (ITRs) of 1883 bp. Within 20 nucleotides of the termini, there is a sequence that is conserved in other poxviruses and is required for the resolution of concatemeric replicative DNA intermediates. The nucleotide composition of the genome is 73% A+T, but the ITRs are only 63% A+T. The genome contains 151 tightly packed open reading frames (ORFs) that either are > or =180 nucleotides in length or are conserved in other poxviruses. ORFs within 23 kb of each end are transcribed toward the termini, whereas ORFs within the central region of the genome are encoded on either DNA strand. In the central region ORFs have a conserved position, orientation, and sequence compared with vaccinia virus ORFs and encode many enzymes, transcription factors, or structural proteins. In contrast, ORFs near the termini are more divergent and in seven cases are without counterparts in other poxviruses. The YLDV genome encodes several predicted immunomodulators; examples include two proteins with similarity to CC chemokine receptors and predicted secreted proteins with similarity to MHC class I antigen, OX-2, interleukin-10/mda-7, poxvirus growth factor, serpins, and a type I interferon-binding protein. Phylogenic analyses indicated that YLDV is very closely related to yaba monkey tumor virus, but outside the yatapoxvirus genus YLDV is more closely related to swinepox virus and leporipoxviruses than to other chordopoxvirus genera.  (+info)

(2/24) A secreted high-affinity inhibitor of human TNF from Tanapox virus.

A class of secreted poxvirus tumor necrosis factor (TNF)-binding proteins has been isolated from Tanapox-infected cell supernatants. The inhibitor bound to a TNF-affinity column and was identified as the product of the 2L gene. Sequence analysis of 2L family members from other yatapoxviruses and swinepox virus yielded no sequence homology to any known cellular gene. The expressed Tanapox virus 2L protein bound to human TNF with high affinity (K(d) = 43 pM) and exhibits an unusually slow off-rate. However, 2L is unable to bind to a wide range of human TNF family members. The 2L protein can inhibit human TNF from binding to TNF receptors I and II as well as block TNF-induced cytolysis. Thus, Tanapox virus 2L represents an inhibitor of human TNF and offers a unique strategy with which to modulate TNF activity.  (+info)

(3/24) Complete genomic sequence and comparative analysis of the tumorigenic poxvirus Yaba monkey tumor virus.

The Yatapoxvirus genus of poxviruses is comprised of Yaba monkey tumor virus (YMTV), Tanapox virus, and Yaba-like disease virus (YLDV), which all have the ability to infect primates, including humans. Unlike other poxviruses, YMTV induces formation of focalized histiocytomas upon infection. To gain a greater understanding of the Yatapoxvirus genus and the unique tumor formation properties of YMTV, we sequenced the 134,721-bp genome of YMTV. The genome of YMTV encodes at least 140 open reading frames, all of which are also found as orthologs in the closely related YLDV. However, 13 open reading frames found in YLDV are completely absent from YMTV. Common to both YLDV and YMTV are the unusually large noncoding regions between many open reading frames. To determine whether any of these noncoding regions might be functionally significant, we carried out a comparative analysis between the putative noncoding regions of YMTV and similar noncoding regions from other poxviruses. This approach identified three new gene poxvirus families, defined as orthologs of YMTV23.5L, YMTV28.5L, and YMTV120.5L, which are highly conserved in virtually all poxvirus species. Furthermore, the comparative analysis also revealed a 40-bp nucleotide sequence at approximately 14,700 bases from the left terminus that was 100% identical in the comparable intergene site within members of the Yatapoxvirus, Suipoxvirus, and Capripoxvirus genera and 95% conserved in the Leporipoxvirus genus. This conserved sequence was shown to function as a poxvirus late promoter element in transfected and infected cells, but other functions, such as an involvement in viral replication or packaging, cannot be excluded. Finally, we summarize the predicted immunomodulatory protein repertoire in the Yatapoxvirus genus as a whole.  (+info)

(4/24) Yaba-like disease virus protein Y144R, a member of the complement control protein family, is present on enveloped virions that are associated with virus-induced actin tails.

Yaba-like disease virus (YLDV) is a yatapoxvirus, a group of slow-growing poxviruses from primates. Analysis of the growth cycle of YLDV in tissue culture showed that maximum virus titres were reached 3 days post-infection and at this time only 3.3 % of infectious progeny was extracellular. The intracellular and extracellular virions have different buoyant densities and are separable on CsCl density gradients. They are also distinguishable by electron microscopy with the extracellular virions having an additional lipid envelope. In YLDV-infected cells, thick actin bundles with virions at their tips were seen protruding from the cell surface, despite the fact that YLDV lacks a protein comparable to Vaccinia virus A36R, which is required for VV-induced actin tail formation. In addition to these observations, the YLDV gene Y144R was characterized. This gene is predicted to encode a transmembrane protein containing three short consensus repeat (SCR) motifs common to members of the complement control protein family. Antibody generated against recombinant Y144R recognized products of 36, 41 and 48-55 kDa in YLDV-infected cells and purified extracellular enveloped virus (EEV) but not intracellular mature virus (IMV). Y144R protein is a glycoprotein with type I membrane topology that is synthesized early and late during infection. By immunoblot, indirect immunofluorescence and immuno-cryoelectron microscopy the Y144R protein was detected on the intracellular enveloped virus (IEV), cell-associated enveloped virus (CEV) and EEV. This represents the first study of a YLDV IEV, CEV and EEV protein at the molecular level.  (+info)

(5/24) Alterations of enzymes associated with plasma membranes and cellular organelles during infection of CV-1 cells with Yaba tumor poxvirus.

The formation of cellular aggregates (foci) in CV-1 cells following infection with Yaba tumor poxvirus is dependent upon cell passage level, temperatue of incubation, and calcium concentration in the medium. Resistance of older cells can be reversed by maintaining calcium at 0.1 mM or by adding cortisone acetate (1 mug/ml), hydrocortisone, or estradiol-17beta to the cultures. In susceptible cells, foci formation was inhibited slightly by methyltestosterone and inhibited completely by dexamethasone, aldosterone and progesterone. Activities and patterns of enzymes associated with cytoplasmic membranes (alkaline phosphatase, mononucleotidase, and Na+-K+-adenosine triphosphatase) and lysosomes (beta-glucuronidase and acid phosphatase) of the younger susceptible and the older resistant CV-1 cells differed. These differences apparently occurred in concert with phenotypic changes in the membranes that reduced the mobility of older resistant cells. In susceptible culture, unifected cells migrated to the infected cell and participated in foci formation. Reduction of the calcium content to 0.1 mM apparently removed some of the constraints on mobility of the resistant cells. Although the hormones may have had a similar effect, the changes in enzyme patterns indicated basic alterations in protein synthesis. The development of resistance to foci formation occurred between the 45th and 50th passage level. Hormonal reversal of this resistance resulted in enzyme profiles that reflected the pattern of young susceptible cells.  (+info)

(6/24) Proteins of Yaba monkey tumor virus I. Structural proteins.

Yaba virus proteins were characterized by polyacrylamide gel electrophoresis. Electrophoresis of Yaba virion (proteins) dissociated by sodium dodecyl sulfate and 2-mercaptoethanol in continuous and discontinuous buffer systems yielded 37 polypeptide species by staining and by counting bands of radioactively labeled polypeptides. The molecular weights of the viral polypeptide species were found to range from 10,000 to 220,000 by comparing the relative distance of migration of viral proteins with proteins of known molecular weights. Two polypeptides were removed from purified virions by nonionic detergent nonidet P -40 treatment, and the amount of one polypeptide was reduced. Purified cores yielded 21 polypeptide species, none of which was labeled with radioactive glucosamine.  (+info)

(7/24) Yaba monkey tumor virus encodes a functional inhibitor of interleukin-18.

Interleukin-18 (IL-18) is a critical proinflammatory cytokine whose extracellular bioactivity is regulated by a cellular IL-18 binding protein (IL-18BP). Many poxviruses have acquired variants of this IL-18BP gene, some of which have been shown to act as viral virulence factors. Yaba monkey tumor virus (YMTV) encodes a related family member, 14L, which is similar to the orthopoxvirus IL-18BPs. YMTV 14L was expressed from a baculovirus system and tested for its ability to bind and inhibit IL-18. We found that YMTV 14L bound both human IL-18 (hIL-18) and murine IL-18 with high affinity, at 4.1 nM and 6.5 nM, respectively. YMTV 14L was able to fully sequester hIL-18 but could only partially inhibit the biological activity of hIL-18 as measured by gamma interferon secretion from KG-1 cells. Additionally, 17 hIL-18 point mutants were tested by surface plasmon resonance for their ability to bind to YMTV 14L. Two clusters of hIL-18 surface residues were found to be important for the hIL-18-YMTV 14L interaction, in contrast to results for the Variola virus IL-18BP, which has been shown to primarily interact with a single cluster of three amino acids. The altered binding specificity of YMTV 14L most likely represents an adaptation resulting in increased fitness of the virus and affirms the plasticity of poxviral inhibitor domains that target cytokines like IL-18.  (+info)

(8/24) Distribution of Lednice (Yaba 1) virus in the chick embryo.

Distribution of Lednice (Yaba 1) virus antigen (LVA) was followed by immunofluorescene (IF) in chick embryos inoculated into the yolk sacs. Positive fluorescence of LVA was observed in neurons and neuroblasts of the developing brain, spinal cord and spinal ganglia as well as in skeletal muscles, heart muscle, vascular endothelium and lung mesenchyma. In the yolk sac, foci of specific fluorescence were occasionally seen in endothelium cells of vessels and in islands of extraembryonic haematopoesis. At sites corresponding to the occurrence of LVA, extensive oedema was accompanied by extravazation of erythrocytes and accumulation of white blood cells. The nature of tissues in which the virus replicates was discussed from the point of view of LVA distribution and the morphological lesions observed.  (+info)