African swine fever virus encodes a gene with extensive homology to type II DNA topoisomerases.

Nucleotide sequencing of a virulent African swine fever virus (ASFV) isolate (Malawi LIL20/1) identified an open reading frame of 1191 amino acid residues encoding a protein of 134.9 kDa. This gene mapped to the SalI i and j restriction endonuclease fragments of the ASFV genome. The predicted polypeptide was found to share 21.1% identity over a 1077 amino acid region with the human type II DNA topoisomerase. The sequence is compared to other type II DNA topoisomerases and the possible roles in ASFV replication are discussed.     

Expression and characterization of the thymidine kinase gene of African swine fever virus.

The thymidine kinase (TK) gene of African swine fever virus (ASFV) was located within the viral genome by using two degenerate oligonucleotide probes derived from sequences of the vaccinia virus and cellular TK genes. The TK gene was mapped within a 0.72-kbp BglII-XhoI fragment (0.242 to 0.246 map units) derived from a 23.9-kbp SalI-B fragment of the ASFV genome. Identification of this region as the ASFV TK gene was confirmed by expression of TK in Escherichia coli and by the synthesis of active TK in a cell-free system programmed with RNA synthesized in vitro. The sequenced gene for TK includes an open reading frame of 588 nucleotides encoding a protein of 196 amino acids. The deduced amino acid sequence shows 32.4% identity with the TK of vaccinia virus.     

非洲猪瘟病毒j5R膜蛋白的电脑预测和实验证实

蛋白多肽二级结构的电脑预测表明,非洲猪瘟病毒（ Ａｆｒｉｃａｎ ｓｗｉｎｅ ｆｅｖｅｒ ｖｉｒｕｓ , Ａ Ｓ Ｆ Ｖ）ｊ５ Ｒ阅读框编码１２ ．９ ｋ Ｄａ 膜蛋白。该蛋白的 Ｃ 末端含有一个潜在抗原决定簇,针对其合成肽的抗体能在 Ａ Ｓ Ｆ Ｖ 感染细胞和病毒颗粒中检测到２３ 或２５ ｋ Ｄａ（ 取决于不同毒株） 特异蛋白。免疫荧光试验显示,ｊ５ Ｒ 蛋白主要位于感染细胞的病毒复制部位。油水两相分离和细胞分级分离试验结果证明ｊ５ Ｒ 蛋白是膜相关蛋白     

Interaction of tomato mosaic virus movement protein with tobacco RIO kinase

Tomato mosaic virus (ToMV) has a regulatory gene encoding a movement protein (MP) that is involved in the cell-to-cell movement of viral RNA through plasmodesmata. To identify the host cell factors interacting with ToMV MP, we used a recombinant MP probe to isolate cDNA clones from a phage expression library of Nicotiana tabacum by a far-Western screening method. One of the cDNA clones encoded an MP-interacting protein, MIP-T7, homologous to the yeast novel protein kinase, Rio1p. We isolated a full-length cDNA by RT-PCR. The putative gene product was designated NtRIO, and shared 33 and 73% amino acid identity with yeast and Arabidopsis RIO kinases, respectively. In vitro analyses using recombinant proteins showed that NtRIO also interacted with a different MP derived from Cucumber mosaic virus. NtRIO had autophosphorylation activity and phosphorylated ToMV MP. Addition of recombinant tobacco casein kinase 2 resulted in a marked increase in the phosphorylation of NtRIO. The interaction between NtRIO and ToMV MP was inhibited by phosphorylation of NtRIO.     

Vaccinia and cowpox viruses encode a novel secreted interleukin-1-binding protein.

Supernatants from vaccinia virus (VV)-infected CV-1 cells were examined and found to contain a 33 kd protein capable of binding murine interleukin-1 beta (mIL-1 beta). A VV open reading frame (ORF) that exhibits 30% amino acid identity to the type II IL-1 receptor was expressed in CV-1-EBNA cells and shown specifically to bind mIL-1 beta. A similar ORF from cowpox virus was expressed and also specifically bound mIL-1 beta. A recombinant VV was constructed in which this ORF was disrupted (vB15RKO). Supernatants from vB15RKO-infected cells did not contain an IL-1-binding protein. Supernatants from VV-infected CV-1 cells were capable of inhibiting IL-1-induced murine lymphocyte proliferation in vitro while supernatants from vB15RKO infected cells did not. Intracranial inoculation of mice with vB15RKO suggests that this ORF is involved in VV virulence. The possible role of a virus-encoded IL-1-binding protein in the pathology of a poxvirus infection and its relationship to other poxvirus-encoded immune modulators is discussed.     

Expression of recombinant capsid proteins of chitta virus, a genogroup II Norwalk virus, and development of an ELISA to detect the viral antigen

The second open reading frame (ORF2) gene of the Chitta virus (CHV) was cloned to construct a recombinant baculovirus. The CHV ORF2 is predicted to encode a capsid protein of 535 amino acids (aa). CHV showed a high aa identity in the capsid region with genogroup II Norwalk virus (NV) (65-85%), but a low aa identity with genogroup I NV (44-46%). Phylogenetic analysis of the ORF2 gene demonstrated that CHV is genetically closely related to the Hawaii virus included in genogroup II NV. The recombinant capsid protein of CHV (rCHV) self-assembled to form empty virus-like particles (VLPs) when expressed in insect cells with the recombinant baculovirus. An enzyme-linked immunosorbent assay (ELISA) based on antisera to rCHV was developed to detect CHV antigen in stools. The antigen ELISA appeared to be highly specific to both rCHV and CHV-like strains. In addition, combined use of antigen ELISAs using antibodies against two antigenically distinct recombinant VLPs, the recombinant Chiba virus (rCV) and recombinant Seto virus (rSEV), enabled us to determine the genetic as well as antigenic relationship among these three viruses.     

Phosphorylation of varicella-zoster virus open reading frame (ORF) 62 regulatory product by viral ORF 47-associated protein kinase.

Varicella-zoster virus (VZV) encodes within its unique long region a gene product with protein kinase motifs. In a previous study, we demonstrated that immunoprecipitated VZV open reading frame (ORF) 47 protein was associated with a functional protein kinase activity, on the basis of its ability to both autophosphorylate and phosphorylate artificial substrates. To further define potential substrates of ORF 47-associated protein kinase, we analyzed individual viral phosphoproteins to determine whether any were modified by the viral protein kinase. These candidates included gene products of VZV ORFs 4, 61, 62, and 63, which are homologs of herpes simplex virus type 1 (HSV-1) immediate-early proteins. Each of the above VZV proteins was coimmunoprecipitated with ORF 47 kinase, and the immune complex was incubated in a protein kinase assay. Under these conditions, only the VZV immediate-early ORF 62 protein was phosphorylated by ORF 47-associated protein kinase. The specificity of this phosphorylation event was analyzed by a competition assay in which a recombinant ORF 47 protein lacking enzymatic activity was able to reduce the amount of phosphorylation of ORF 62 protein by VZV ORF 47-associated kinase. To provide an additional evaluation of specificity, the experiment was repeated with [32P]GTP instead of [32P]ATP, because the VZV ORF 47 kinase has the distinctive property of using GTP as a phosphate donor. Again the ORF 62 substrate was phosphorylated. In summary, the VZV ORF 47-associated protein kinase (the HSV-1 UL13 homolog) catalyzed the in vitro phosphorylation of the VZV ORF 62 protein, the homolog of the HSV-1 ICP4 regulatory protein.     

Characterization of a ubiquitinated protein which is externally located in African swine fever virions.

An antiserum was raised against the African swine fever virus (ASFV)-encoded ubiquitin-conjugating enzyme (UBCv1) and used to demonstrate by Western blotting (immunoblotting) and immunofluorescence that the enzyme is present in purified extracellular virions, is expressed both early and late after infection of cells with ASFV, and is cytoplasmically located. Antiubiquitin serum was used to identify novel ubiquitin conjugates present during ASFV infections. This antiserum stained virus factories late after infection, suggesting that virion proteins may be ubiquitinated. This possibility was confirmed by Western blotting, which identified three major antiubiquitin-immunoreactive proteins with molecular masses of 5, 18, and 58 kDa in purified extracellular virions. The 18-kDa protein was solubilized from virions at relatively low concentrations of the detergent n-octyl-beta-D-glucopyranoside, indicating that it is externally located and is possibly in the virus capsid. The 18-kDa protein was purified, and N-terminal amino acid sequencing confirmed that the protein was ubiquitinated and was ASFV encoded. The ASFV gene encoding this protein (PIG1) was sequenced, and the encoded protein expressed in an Escherichia coli expression vector. Recombinant PIG1 was ubiquitinated in the presence of E. coli expressed UBCv1 in vitro. These results suggest that PIG1 may be a substrate for UBCv1. The predicted molecular masses of the PIG1 protein and recombinant ubiquitinated protein were larger than the 18-kDa molecular mass of the ubiquitinated protein present in virions. Therefore, during viral replication, a precursor protein may undergo limited proteolysis to generate the ubiquitinated 18-kDa protein.     

Molecular cloning of a chicken JAK homolog from activated T cells

A cDNA encoding a JAK-related protein was isolated from a chicken T cell library by screening with a PCR-generated probe that corresponds to a conserved region in the kinase domain. Sequence analysis reveals an ORF of 3318 nt, encoding a protein with a calculated molecular weight of 123 000. Chicken JAK (cJAK) contains a double catalytic domain that is characteristic of the JAK family of tyrosine kinases. Compared with mammalian JAKs, the kinase domain shows 70% sequence identity with the corresponding region of the mammalian JAKs. Overall, cJAK shows approximately 59% amino acid identity with mammalian JAK3s, and 52% amino acid identity with mammalian JAK2s. cJAK is expressed predominantly in thymus and spleen, with lower levels in kidney, thyroid and liver. cJAK is also expressed at low levels in unstimulated splenic T cells, whereas mRNA levels are increased after activation of the T cells with Con A. The sequence analysis and pattern of expression suggests that this is an avian homolog of JAK3.     

Isolation and characterization of a <Emphasis Type="Italic">Paramecium</Emphasis> cDNA clone encoding a putative serine/threonine protein kinase

Mitogen-activated protein (MAP) kinases, a closely related family of protein kinases, are involved in cell cycle regulation and differentiation in yeast and human cells. They have not been documented in ciliates. We used PCR to amplify DNA sequences of a ciliated protozoan—Paramecium caudatum—using primers corresponding to amino acid sequences that are common to MAP kinases. We isolated and sequenced one putative MAP kinase-like serine/threonine kinase cDNA from P. caudatum. This cDNA, called pcstk1 (Paramecium caudatum Serine/Threonine Kinase 1) shared approximately 35% amino acid identity with MAP kinases from yeast. MAP kinases are activated by phosphorylation of specific threonine and tyrosine residues. These two amino acid residues are conserved in the PCSTK1 sequence at positions Thr 159 and Tyr 161. The PSTAIRE motif, which is characteristic of the CDK2 gene family, cannot be found in ORF of PCSTK1. The highest homology score was to human STK9, which contains MAP type kinase domains. Comparisons of expression level have shown that pcstk1 is expressed equally in cells at different stages (sexual and asexual). We discussed the possibility, as in other organisms, that a family of MAP kinase genes exists in P. caudatum.     

African swine fever virus encodes two genes which share significant homology with the two largest subunits of DNA-dependent RNA polymerases.

A random sequencing strategy applied to two large SalI restriction fragments (SB and SD) of the African swine fever virus (ASFV) genome revealed that they might encode proteins similar to the two largest RNA polymerase subunits of eukaryotes, poxviruses and Escherichia coli. After further mapping by dot-blot hybridization, two large open reading frames (ORFs) were completely sequenced. The first ORF (NP1450L) encodes a protein of 1450 amino acids with extensive similarity to the largest subunit of RNA polymerases. The second one (EP1242L) codes for a protein of 1242 amino acids similar to the second largest RNA polymerase subunit. Proteins NP1450L and EP1242L are more similar to the corresponding subunits of eukaryotic RNA polymerase II than to those of vaccinia virus, the prototype poxvirus, which shares many functional characteristics with ASFV. ORFs NP1450L and EP1242L are mainly expressed late in ASFV infection, after the onset of DNA replication.     

ORF66 protein kinase function is required for T-cell tropism of varicella-zoster virus in vivo

Several functions have been attributed to the serine/threonine protein kinase encoded by open reading frame 66 (ORF66) of varicella-zoster virus (VZV), including modulation of the apoptosis and interferon pathways, down-regulation of major histocompatibility complex class I cell surface expression, and regulation of IE62 localization. The amino acid sequence of the ORF66 protein contains a recognizable conserved kinase domain. Point mutations were introduced into conserved protein kinase motifs to evaluate their importance to ORF66 protein functions. Two substitution mutants were generated, including a G102A substitution, which blocked autophosphorylation and altered IE62 localization, and an S250P substitution, which had no effect on either autophosphorylation or IE62 localization. Both kinase domain mutants grew to titers equivalent to recombinant parent Oka (pOka) in vitro. pOka66G102A had slightly reduced growth in skin, which was comparable to the reduction observed when ORF66 translation was prevented by stop codon insertions in pOka66S. In contrast, infection of T-cell xenografts with pOka66G102A was associated with a significant decrease in infectious virus production equivalent to the impaired T-cell tropism found with pOka66S infection of T-cell xenografts in vivo. Disrupting kinase activity with the G102A mutation did not alter IE62 cytoplasmic localization in VZV-infected T cells, suggesting that decreased T-cell tropism is due to other ORF66 protein functions. The G102A mutation reduced the antiapoptotic effects of VZV infection of T cells. These experiments indicate that the T-cell tropism of VZV depends upon intact ORF66 protein kinase function.     

Isolation and characterization of two evolutionarily conserved murine kinases (Nek6 and nek7) related to the fungal mitotic regulator, NIMA

Entrance and exit from mitosis in Aspergillus nidulans require activation and proteolysis, respectively, of the NIMA (never in mitosis, gene A) serine/threonine kinase. Four different NIMA-related kinases were reported in mammals (Nek1-4), but none of them has been shown to perform mitotic functions related to those demonstrated for NIMA. We describe here the isolation of two novel murine protein kinase genes, designated nek6 and nek7, which are highly similar to each other (87% amino acid identity in the predicted kinase domain). Interestingly, Nek6 and Nek7 are also highly similar to the F19H6.1 protein kinase of Caenorhabditis elegans (76 and 73% amino acid identity in the kinase domain, respectively), and phylogenetic analysis suggests that these three proteins constitute a novel subfamily within the NIMA family of serine/threonine kinases. In contrast to the other documented NIMA-related kinases, Nek6/7 and F19H6.1 harbor their catalytic domain in the C-terminus of the protein. Immunofluorescence suggests that Nek6 and Nek7 are cytoplasmic. Linkage analysis, using the murine BXD recombinant inbred strain panel, localized nek6 to chromosome 2 at 28 cM. Using a mouse/hamster radiation hybrid panel, we assigned the nek7 gene to chromosome 1 at approximately 73 cM.     

Nucleotide sequence and molecular characterization of the structural glycoprotein gp41 gene homologue of Spodoptera litura nucleopolyhedrosis virus (spltNPV-I)

The structural glycoprotein gene gp41 homologue of Spodoptera litura nucleopolyhedrosis virus (SpltNPV-I *) was identified in the 4.0 kb EcoRI-L fragment of the viral genome. The nucleotide sequence of 2063 bp of this fragment revealed an open reading frame of 1014 nucleotides to encode a polypeptide of 337 amino acids. Analysis of nucleotide and deduced amino acid sequences of the putative ORF indicated its identity with gp41 protein of other baculoviruses sharing maximum homology with that of Spodoptera frugiperda nucleopolyhedrosis virus (SfNPV). The coding sequence was preceded by an AT-rich region containing the consensus baculoviral late promoter motif RTAAG. The putative SpltNPV gp41 ORF was abundantly expressed as a 37 kDa apoprotein in E. coli and as a 50 kDa glycoprotein in Sf9 cells. The recombinant protein expressed in insect cells was glycosylated (20%) and has GlcNAc as the terminal sugar. The gene is conserved among baculoviruses and places SpltNPV-I close to Spodoptera frugiperda and Spodoptera exigua NPVs in phylogenetic tree.     

Varicella-zoster virus ORF47 protein serine kinase: characterization of a cloned, biologically active phosphotransferase and two viral substrates, ORF62 and ORF63

Varicella-zoster virus (VZV) codes for a protein serine kinase called ORF47; the herpes simplex virus (HSV) homolog is UL13. No recombinant alphaherpesvirus serine kinase has been biologically active in vitro. We discovered that preservation of the intrinsic kinase activity of recombinant VZV ORF47 required unusually stringent in vitro conditions, including physiological concentrations of polyamines. In this assay, ORF47 phosphorylated two VZV regulatory proteins: the ORF62 protein (homolog of HSV ICP4) and the ORF63 protein (homolog of HSV ICP22). Of interest, ORF47 kinase also coprecipitated ORF63 protein from the kinase assay supernatant.     

Vimentin rearrangement during African swine fever virus infection involves retrograde transport along microtubules and phosphorylation of vimentin by calcium calmodulin kinase II

African swine fever virus (ASFV) infection leads to rearrangement of vimentin into a cage surrounding virus factories. Vimentin rearrangement in cells generally involves phosphorylation of N-terminal domains of vimentin by cellular kinases to facilitate disassembly and transport of vimentin filaments on microtubules. Here, we demonstrate that the first stage in vimentin rearrangement during ASFV infection involves a microtubule-dependent concentration of vimentin into an "aster" within virus assembly sites located close to the microtubule organizing center. The aster may play a structural role early during the formation of the factory. Conversion of the aster into a cage required ASFV DNA replication. Interestingly, viral DNA replication also resulted in the activation of calcium calmodulin-dependent protein kinase II (CaM kinase II) and phosphorylation of the N-terminal domain of vimentin on serine 82. Immunostaining showed that vimentin within the cage was phosphorylated on serine 82. Significantly, both viral DNA replication and Ser 82 phosphorylation were blocked by KN93, an inhibitor of CaM kinase II, suggesting a link between CaM kinase II activation, DNA replication, and late gene expression. Phosphorylation of vimentin on serine 82 may be necessary for cage formation or may simply be a consequence of activation of CaM kinase II by ASFV. The vimentin cage may serve a cytoprotective function and prevent movement of viral components into the cytoplasm and at the same time concentrate late structural proteins at sites of virus assembly.