- Volume 71, Issue 2, 1990
Volume 71, Issue 2, 1990
- Animal
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Functional analysis of a 603 nucleotide open reading frame upstream of the polyhedrin gene of Autographa californica nuclear polyhedrosis virus
More LessThe sequence of the 2000 nucleotides immediately upstream of the polyhedrin gene of the Autographa californica multiple nucleocapsid nuclear polyhedrosis virus has been determined. Comparative analysis of the data identified a 603 nucleotide open reading frame (ORF) separated from the polyhedrin gene coding sequences by 156 nucleotides and in the opposite strand of DNA. Northern hybridization analysis of polyadenylated RNA from infected cells highlighted a 3·7 kb species produced maximally at 12 h postinfection, but not in the presence of cycloheximide. Preliminary nuclease SI analysis of the 5′ end of this RNA suggested that it initiated at a position very close to that of the polyhedrin mRNA start site. Deletion of a portion of the ORF 603 from viruses containing the normal polyhedrin gene and the lacZ gene in lieu of polyhedrin did not affect replication in cell culture or the production of β-galactosidase protein. A virus which lacked the ORF 603 gene but produced polyhedrin had similar infectivity in Trichoplusia ni larvae compared to the wild-type virus. The chloramphenicol acetyltransferase (CAT) gene was also inserted in lieu of the ORF 603 in a virus containing the lacZ gene instead of the polyhedrin (Ac.CAT.lacZ). Analysis of CAT expression revealed that a maximum level was reached at 16 h p.i. and that transcription was initiated in Ac. CAT .lacZ at the same site as for the normal gene.
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Primary structure of the S peplomer gene of bovine coronavirus and surface expression in insect cells
More LessThe nucleotide sequence of the S peplomer gene of bovine coronavirus (BCV) has been determined. A single open reading frame of 4089 nucleotides encodes a polypeptide of 150K with 20 potential sites for addition of N-linked oligosaccharides. Expression of the cloned BCV S gene by a recombinant of Autographa californica nuclear polyhedrosis virus resulted in production of a 180K glycosylated polypeptide which was transported to the surface of the cell. Comparison of the BCV S gene with the analogous genes of murine hepatitis viruses shows that the BCV S polypeptide contains a unique domain of 138 amino acids not present in murine hepatitis virus strain JHM, but which has a partially homologous counterpart in strain A59. This domain accounts for most of the differences in size of the S gene products of these coronaviruses.
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Localization of antigenic sites of the E2 glycoprotein of transmissible gastroenteritis coronavirus
Four antigenic sites of the E2 glycoprotein of transmissible gastroenteritis virus were defined by competitive radioimmunoassays of monoclonal antibodies (MAbs). Here, we describe the localization of these sites by testing the antigenicity of protein fragments and prokaryotic expression products of E2 gene fragments, and by sequencing of MAb-resistant (mar) mutants. Partial proteolysis of purified E2 protein allowed the isolation of a 28K fragment recognized by both site A- and site C-specific MAbs. An antiserum against this fragment bound to a synthetic peptide containing residues 1 to 18 and to an expression product containing residues 1 to 325. The same expression product was recognized by site C-specific MAbs. These data indicate that residues within the sequence 1 to 325 contribute to site C and possibly also to site A. Sequencing of mar mutants that escaped neutralization by site A-specific MAbs indicated that residues 538 and 543 also belong to site A. The binding of site-specific MAbs to expression products led directly to the localization of sites B and D, between residues 1 to 325 and 379 to 529, respectively. The first 37 % of the polypeptide chain of E2 appears to be more immunogenic than the rest of the sequence.
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Protection against rabies in mice by a cytotoxic T cell clone recognizing the glycoprotein of rabies virus
By the use of liposomes containing the purified surface glycoprotein (G) of rabies virus and the haemagglu- tinin-neuraminidase (HN) and fusion (F) glycoproteins of Sendai virus, the target antigen of anti-rabies virus cytotoxic T lymphocyte (CTL) clones isolated in a previous study was identified as the G protein. Recognition of the H-2K determinant of the class I major histocompatibility complex (MHC) was necessary for target lysis by the CTL clones. One of the CTL clones was examined for the ability to protect mice against a lethal rabies virus infection. CTL were transferred into syngeneic mice which had been infected in the hind footpad with the ERA strain of rabies virus. The infection was converted into a lethal infection by cyclophosphamide treatment 1 day after virus infection. Transfer of CTL 2 to 3 days after virus infection protected approximately 50% of mice during the observation period of 4 weeks. Greater protection was obtained in mice receiving both anti-rabies virus antibodies and CTL cells.
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A minor microtubule-associated protein is responsible for the stimulation of vesicular stomatitis virus transcription in vitro
More LessAn activity found in bovine brain microtubule-associated proteins (MAPs) which stimulated vesicular stomatitis virus (VSV) transcription in vitro co-eluted from a gel filtration column (Sepharose CL-6B) with a minor MAP subset of an apparent M r of 100000 to 250000. The activity did not appear to be closely associated with MAPs 1, MAPs 2, tau or tubulin. Anti-MAPs 1 and anti-MAPs 2 IgG did not reduce or abolish the stimulatory activity. The bovine brain MAPs stimulatory activity was similar to that found in HeLa cell extracts: both were heat-resistant, and both co-purified with the MAPs fraction of cell extracts; also amounts of each which gave maximum stimulation when used separately did not give additional stimulation when combined. Fractions from the Sepharose CL-6B column that contained the greatest amount of stimulatory activity exhibited little or no cAMP-dependent or -independent kinase activity. The MAPs stimulatory activity required the presence of both L and NS polymerase subunits.
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Sequence of the large double-stranded RNA segment of the N1 strain of infectious pancreatic necrosis virus: a comparison with other Birnaviridae
More LessThe cDNA sequence of the large dsRNA segment (segment A) of the N1 strain of infectious pancreatic necrosis virus (IPNV) has been determined. The nucleotide and deduced amino acid sequences were compared to the sequences of segment A of the Jasper strain of IPNV and to the sequences of segments A and B (5′ and 3′ flanking regions) of the 002–73 strain of infectious bursal disease virus (IBDV). The comparison demonstrated that the precursor protein of the major structural polypeptide, pVP2, is highly conserved at the N and C termini, whereas the amino acid sequence of an internal segment shows greater diversity between the strains. This internal segment probably carries the serotype-specific epitopes of birnaviruses. An alternative open reading frame (ORF) (444 bp) partly overlapping with the large ORF (2916 bp) of segment A was found to be conserved among the IPNV strains and is probably also present in the 002–73 strain of IBDV. This small ORF may encode a novel birnavirus polypeptide with an M r of 17K. SDS-PAGE of radiolabelled purified IPNV particles revealed a band corresponding to the possible novel 17K polypeptide. Short terminal inverted repeats are found in segment A of the N1 and Jasper strains of IPNV and in segment B of the 002–73 strain of IBDV. Segment A of IPNV and segment B of IBDV also contain adjacent inverted repeats at their 5′-terminal flanking regions.
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Heterotypic recognition of foot-and-mouth disease virus by cattle lymphocytes
T. Collen and T. R. DoelLymphoproliferation against foot-and-mouth disease (FMD) virus was examined using peripheral blood mononuclear cells from vaccinated cattle. Ten weeks after revaccination the optimum conditions for proliferation were obtained with 1 μg/ml of purified virus after 5 to 6 days in culture. This contrasted with the response at 20 months post-revaccination, when the response required less antigen and showed a peak response after 3 to 4 days in culture. Proliferation was specific for FMD virus, but was cross-reactive between serotypically distinct strains of the virus. The proliferative response to isolated virus proteins (VP) involved all three major capsid proteins (VP1, −2 and −3), although the proliferation of lymphocytes from heterotypically vaccinated cattle was due to VP3. Furthermore, the response induced by purified virus, chemically fixed virus and subunit virus particles was indistinguishable and thus it is likely that processing was required for the induction of proliferation. Together these data strongly suggest that FMD virus-induced lymphoproliferation is T cell-mediated and that VP3 may contain dominant, cross-reactive sequences.
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Rapid molecular evolution of wild type 3 poliovirus during infection in individual hosts
More LessA panel of nine neutralizing monoclonal antibodies was used to analyse the antigenic properties of 188 plaque- purified type 3 poliovirus strains from 17 faecal specimens, derived from eight people during a 2 month observation period. Most poliovirus specimens consisted of a mixture of antigenically distinct variants and the composition of the mixture was found to change between sequential specimens in many individuals, indicating antigenic evolution. Thirty-five strains representing different antigenic patterns were selected for partial sequencing of genomic RNA. Mutations leading to amino acid substitutions, as well as silent mutations, were seen at and close to the known antigenic sites. The frequency of silent mutations was used to estimate the evolutionary potential of the virus. The largest difference in silent changes between strains isolated from one person was 0 ·8 %, which corresponds to a minimum of about 60 mutations per genome within a period of 3 weeks. The observed incidence of silent mutations between isolates from different persons was usually between 0·8 and 2%. These figures agree with the previously reported overall mutation rates of poliovirus, determined by other methods.
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Studies on the pathogenicity of a nairovirus, Dugbe virus, in normal and immunosuppressed mice
More LessSusceptibility to lethal infection with the KT281/75 strain of the tick-borne nairovirus, Dugbe virus, was similar in an outbred strain and several inbred strains of mice. For the outbred strain, both neural and extraneural routes of virus inoculation resulted in lethal infection, but susceptibility decreased with age and only intracerebral inoculation produced a lethal infection in adults. In newborn mice, subcutaneous (s.c.) inoculation of virus (analogous to a tick-bite) produced a disseminated infection, titres being highest in the upper respiratory tract (URT), spleen and liver at 5 days postinoculation (p.i.), the heart at 7 days p.i. and brain by 8 days p.i. In neonates inoculated intranasally (i.n.), by contrast, virus spread rapidly from the URT to the brain by 2 days p.i., in the absence of a detectable viraemia. Virus was undetectable in the blood of s.c. and i.n. inoculated adults; in the former, virus replication was limited to the site of inoculation, and in the latter virus grew in the respiratory tract and again spread to the brain. Immunosuppression of i.n. inoculated adult mice with cyclophosphamide produced some mortality indicating that host defences are important in protecting the adult, especially as newborn and adult lung tissue were equally able to support the growth of Dugbe virus in culture. The similarity between the pattern of Dugbe virus infection in the mouse and that of other, more pathogenic nairoviruses suggests that, although haemorrhagic disease was not observed, this may be a useful model for studying the genetic basis of nairovirus virulence and for testing vaccines and anti-viral drugs.
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Cell surface phenotype and human T lymphotropic virus type 1 antigen expression in 12 T cell lines derived from peripheral blood and cerebrospinal fluid of West Indian, Guyanese and African patients with tropical spastic paraparesis
Twelve long-term cell lines were established from peripheral blood mononuclear cells (PBMC) or cerebrospinal fluid cells of patients with human T lymphotropic virus type I (HTLV-I) seropositive tropical spastic paraparesis (TSP) originating from the French West Indies, French Guyana or the Central African Republic. Most of these long-term interleukin-2- dependent cell lines exhibited a pattern characteristic of CD4+-activated T cells with high expression of CD2, CD3 and CD4 antigens, associated with a strong density of TAC and DR molecules. Nevertheless, in five cases CD8 expression was present at a significant level. HTLV-I antigens were never detected in uncultured PBMC, but they were expressed in a few cells after short-term culture and after 4 months the majority of the cells were HTLV-I positive, as demonstrated by indirect immunofluorescence (IF) using polyclonal or monoclonal anti-p19 and anti-p24 antibodies. Low and variable levels of reverse transcriptase activity were detected in supernatant fluids of these cell lines only after 4 months of culture, when at least 50% of the cells exhibited HTLV-I antigens by IF. However, numerous type C HTLV-I-like viral particles were detected, mostly in the extracellular spaces, with rare budding particles. Similar findings were found in three T cell lines derived from West Indian and African patients with adult T-cell leukaemia/lymphoma (ATLL). Differences in high Mt polypeptides were detected by Western blot in cell lysates when comparing TSP- or ATLL-derived T cell lines. Thus a signal of 62K was easily detectable in all the TSP lines, but not in the ATLL lines. In all cell lines bands corresponding to p53, p24 and p19 viral core polypeptides were present, as was the env gene-coded protein p46.
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Molecular cloning and characterization of a defective recombinant feline leukaemia virus associated with myeloid leukaemia
The GM1 strain of feline leukaemia virus (FeLV) was isolated from a naturally occurring case of myeloid leukaemia and induces severe haematopoietic abnormalities, including myeloblastic leukaemia, on inoculation into cats. Molecular clones of FeLV-GMl proviruses were obtained and studied by restriction enzyme mapping, blot hybridization and partial DNA sequence analysis. Two types of clone were isolated; the first was a replication-competent FeLV of subgroup A, resembling other low or minimally pathogenic FeLV-A isolates; the second was replication-defective with extensive deletions and mutations in gag and pol, although it has an intact env gene of subgroup B phenotype. Large segments of the defective proviruses, from the 5′ leader sequence upstream of the gag gene to the 5′ half of the env gene, show structural hallmarks of endogenous FeLV-related proviruses. Infectious FeLV-GMl viruses recovered after transfection were tested for their leukaemogenic potential in newborn cats. Early polyclonal myeloproliferative changes were observed in cats inoculated with FeLV-A/GMl alone, although these were more pronounced in animals receiving the full FeLV-AB/GMl complex reconstituted by cotransfection of the defective virus FeLV-B with its FeLV-A helper. Analysis of viruses in the bone marrow showed that replication of the subgroup B component is delayed and restricted to a proportion of cats. Most of the infected cats developed persistent abnormalities of haematopoiesis and one progressed to disseminated myeloid leukaemia. The defective recombinant FeLV-B/GMl appears to play an indirect but important role in myeloid leukaemogenesis.
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Genome rearrangements in porcine rotaviruses: biochemical and biological comparisons between a supershort strain and its standard counterpart
Two porcine rotavirus strains (CN86 and CC86) isolated during an epidemiological survey of diarrhoea in swine in Argentina were studied because of several unique characteristics. Both these strains were isolated and cloned from the same faecal sample and the electrophoretic migration of 10 of their 11 genomic dsRNA genomic segments in polyacrylamide gels was identical, but strain CC86 had a supershort electro- pherotype. We analysed biochemical, serological and biological properties of both viruses. In vitro translation of genome segment 11 RNAs showed that both viruses produced a polypeptide with an apparent M r of 26K. No differences in any of the other virus-induced proteins made in infected MA104 cells were found on one- and two-dimensional gels for either strain. In addition, the serotype and the subgroup specificities of both viruses were identical (group A, subgroup I, serotype 5). These results suggest that the rearranged strain was probably generated from the standard one and that the coding capacity of the rearranged segment was conserved. Consistent with this hypothesis, primer extension analysis revealed that the supershort strain had a rearrangement involving partial duplication of genomic segment 11. Biological studies showed differences between these viruses. The rearranged strain (CC86) produced larger plaques in monolayers of MA104 cells and outgrew the standard strain (CN86) when cells were coinfected with both viruses at different relative concentrations and different m.o.i. The possibility that large plaque formation and efficient virus replication can be influenced by the products of genomic segment 11, in addition to segment 4, is discussed.
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Interaction of bluetongue virus with bovine lymphocytes
More LessFreshly isolated, and established, cultures of bovine peripheral blood mononuclear leukocytes (PBMLs) were exposed to bluetongue virus (BTV) for the purpose of defining potential lymphotropism. PBML cultures were established in the presence of interleukin 2 (IL-2) and mitogen and maintained either as bulk culture or were cloned prior to infectivity studies. All cultures appeared to be of the T cell phenotype based on the following characteristics: binding of T lymphocyte-specific lectins (i.e. peanut agglutinin and Helix pomatia), rosetting of sheep erythrocytes, binding of a putative pan-T monoclonal antibody, and absence of surface immunoglobulin (Ig). T lymphocyte cultures were further characterized by their ability to elicit lectin-dependent cellular cytotoxicity (LDCC). Exposure of established lymphocyte cultures to BTV resulted in productive cytopathic and non-cytopathic infections. Non-cytopathic productive infections were observed in LDCC-negative cultures whereas cytopathic and non-cytopathic infections were observed in LDCC-positive cultures. Exposure of freshly isolated PBMLs to BTV resulted in minimal virus replication; addition of mitogen and IL-2 to such cultures did not augment virus replication. Addition of mitogen and IL- 2 induced negligible blast transformation, whereas PBML viability was minimally affected. These studies establish a tropism of BTV for bovine T lymphocytes with virus replication being limited to those cells undergoing blastogenesis. Establishment of infected lymphocyte cultures, without loss of culture viability, suggest such an interaction may contribute to the long term viraemias associated with BTV infection of cattle.
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The interaction between bovine herpesvirus type 1 and activated bovine T lymphocytes
More LessThe interaction between activated bovine T lymphocytes (BTLs) and bovine herpesvirus type 1 (BHV-1) was investigated. BHV-1 infection of BTLs reduced the amplitude of recombinant bovine interleukin 2-induced proliferative responses. This decreased proliferation was caused by a virus-induced lymphocytolysis which was dependent on viable virus and was not inhibited by recombinant bovine interferon-α11. Furthermore, lymphocytolysis was not associated with virus replication or with the synthesis of detectable levels of viral proteins. Electron microscopic examination of virus-infected cells revealed that lymphocytolysis was characterized by early nuclear disintegration resembling apoptosis. These observations suggest that activated T cells, localized at the site of BHV-1 infection, may be susceptible to virus-induced cytolysis.
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Epstein-Barr virus receptor expression on human CD8+ (cytotoxic/suppressor) T lymphocytes
More LessIn 1977 we showed that cells of a human lymphocytic leukaemia-derived T line (Molt-4) have receptors for Epstein-Barr virus (EBV). More recently, EBV- positive human T cell lymphomas have been recognized and human T cell lines containing the EBV genome have been established in vitro. To understand better the interaction of EBV with T cells, we decided to determine first whether human peripheral blood T lymphocytes express receptors for EBV. Using flow cytometry we examined the binding of both lymphocyte-transforming (B95-8) and non-transforming (P3HR-1) strains of EBV to T lymphocyte subpopulations, using a double labelling technique with T cell- specific phycoerythrinated monoclonal antibodies (Leu 2a) and fluoresceinated viral preparation. Our results suggest that, in general, about 50% of the CD8+ (or suppressor/cytotoxic) T cell subpopulation from both EBV-seropositive and -seronegative individuals can bind EBV. EBV receptor expression on these T cells was about 10 and 51 times less than that on Molt-4 and Raji (an EBV receptor-positive B cell line) cells, respectively. The specificity of this binding was demonstrated by the inhibition of attachment of viral preparations preincubated with a monoclonal antibody directed against the viral ligand (gp240/350), and by preincubating these target T cells with unlabelled virus. We were unable to detect EBV-induced antigens in infected T cells, suggesting that, as in Molt-4 cells, virus internalization may not occur in fresh T cells and/or that the virus receptor may not be completely functional. We were also unable to detect C3d (or CR2) receptors on these T cells, or to inhibit virus attachment by treating the targets with an anti-CR2 monoclonal antibody (OKB7), suggesting that the EBV receptor on CD8+ peripheral blood lymphocytes is different from that on B cells.
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Cytotoxic T lymphocytes specific for herpes simplex virus (HSV) studied using adenovirus vectors expressing HSV glycoproteins
In previous work, we observed that H-2k-restricted herpes simplex virus (HSV)-specific cytotoxic T lymphocytes (CTLs) were effectively able to lyse transfected target cells expressing HSV glycoprotein C (gC), but not cells expressing gB, gD or gE. To confirm and extend our observations on the specificity of anti-HSV CTLs, recombinant adenovirus (Ad) vectors able to express HSV-1 gB or gC (AdgB2 or AdgC) were constructed. Syngeneic target cells infected with AdgB2 were efficiently lysed by primary H-2b and H-2d, but not by H-2k-restricted HSV-specific CTL. Limiting dilution studies indicated that 4 to 10% of H- 2b-restricted HSV-specific CTLs recognize gB. H-2k, H-2b and H-2d-restricted anti-HSV-1 CTLs were unable to lyse AdgC-infected syngeneic target cells. To examine the apparent discrepancy between the previous results involving transfected H-2k cells expressing gC and the present results involving AdgC-infected cells, gC-expressing cell lines used in previous experiments were subcloned and retested in CTL assays. DC2 cells which were lysed by HSV-specific CTLs in the previous experiments remained sensitive to anti-HSV CTLs but two other clones derived from the same transfection were not lysed. Further, L cells transfected with the gC or gD gene coupled to the mouse mammary tumour virus promoter and capable of expressing high levels of the glycoproteins following dexamethasone induction were not lysed by H-2k-restricted anti-HSV CTLs. These results suggest that HSV-specific CTLs do not recognize gC, at least when it is expressed using an Ad vector and in most transfected cell lines, whereas a significant proportion of anti-viral CTLs recognize gB presented in some but not all murine haplotypes.
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Reactivation of latent infection and induction of recurrent herpetic eye disease in mice
More LessDuring primary ocular infection of mice with herpes simplex virus type 1 (HSV-1) strain McKrae, dendritic corneal ulcers developed and many eyes became permanently damaged. When primary infection had subsided, latent infection was detected in the three parts of the trigeminal ganglion and in the superior cervical ganglion. Such latently infected mice were treated with cyclophosphamide, dexamethasone and u.v. irradiation, or cyclophosphamide and dexamethasone alone. After treatment with immunosuppressive drugs and u.v. irradiation infectious virus was isolated from the ophthalmic part of the trigeminal ganglion, and in eyelids and eyewashings; recurrent herpetic eye disease was seen but only in eyes undamaged by primary infection. After treatment with cyclophosphamide and dexamethasone alone there was a lower incidence of virus isolated from eyewashings and no recurrent disease was seen. There was a good correlation between the pattern and distribution of recurrent lesions and the distribution of cells stained due to the presence of virus antigens.
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Neuroinvasion by herpes simplex virus. An in vitro model for characterization of neurovirulent strains
More LessA cell culture technique with rat dorsal root ganglion neurons cultured in a two-chamber system allowing exposure of neuritic extensions or neuronal cell soma to herpes simplex virus (HSV) infection was exploited for studies of viral neuroinvasiveness. Four groups of HSV strains were investigated. Type 1 strains were isolated from cases of either encephalitis or mucocutaneous infections and type 2 strains were from cases of meningitis or genital infections. The neuroinvasiveness of the type 1 encephalitis strains was significantly greater than the neuroinvasiveness calculated for the type 1 strains of cutaneous origin or for either of the type 2 strains. From our evaluation of the rates of neuritic uptake and axonal transport and the rate of replication in dorsal root ganglion cells and skin fibroblasts, we concluded that the differences observed in neuroinvasiveness probably reflected differences in early virus-nerve cell interactions, i.e. virus attachment and fusion with the neuritic plasma membrane.
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Transfer of UL41, the gene controlling virion-associated host cell shutoff, between different strains of herpes simplex virus
More LessStudies with mutant viruses have suggested that the product of gene UL41 of herpes simplex virus type 1 (HSV-1) controls the virion-mediated inhibition of cellular protein synthesis as well as the rate of degradation of viral mRNAs. HSV-1 strain 17+ has a weak host shutoff function, whereas HSV-2 strain G shuts off strongly. A gene of HSV-2(G), judged from its position in the genome to be the probable analogue of gene UL41 of HSV-1, was inserted into the nonessential thymidine kinase gene of HSV-1(17+). The recombinant virus, 17G41, exhibited a strong shutoff function and its immediate early mRNA did not accumulate in the presence of cycloheximide. It resembled HSV-2(G) in these respects and not the parent, confirming the function of the transferred gene. Recombinant virus 17G41 carries the UL41 genes of both strains, 17+ and G, and in this situation the strong shutoff function was dominant. However, after mixed infection with equal multiplicities of 17G41 and HSV- 1(17+) the weak shutoff function was dominant. The recombinant, 17G41, was further modified by insertion of a lacZ expression cassette into the coding region of the original gene UL41 (17+). The resulting virus, 17(41−)G41, also had a strong shutoff activity but grew poorly in tissue culture.
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Presence and type specificity of papillomavirus antibodies demonstrable by immunoelectron microscopy tests in samples from patients with warts
More LessSera from 75 patients with warts were tested for antibodies against human papillomaviruses (HPVs) in an immunoelectron microscopy test. A group of 40 patients’ sera were tested against a pooled suspension of the HP Vs extracted from their warts and 90% of the sera were found to be antibody-positive. Prior to serological investigation viruses from a second group of 35 patients were typed by dot blot hybridization with HPV-1 and HPV-2 DNA. According to these results the patients were divided into type 1, type 2 and non-1, non-2 virus carriers. Sera of these patients were first tested for antibodies reactive with their homologous viruses and then for antibodies against type 1 virus. More than 80% of the patients possessed antibodies against their homologous viruses, but only a small minority of sera from type 2 and non-1, non-2 virus carriers were reactive with type 1 viruses. These results suggest that the antibody reactive in the immuno- aggregation test is type-specific.
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Human T cell responses to human papillomavirus type 16 L1 and E6 synthetic peptides: identification of T cell determinants, HLA-DR restriction and virus type specificity
Four T cell determinants in the major capsid protein of human papillomavirus (HPV) type 16 LI and one in the E6 protein associated with cellular transformation were defined using synthetic peptides to stimulate peripheral blood mononuclear cells from asymptomatic individuals. HLA-DR restriction was defined using murine L cells transfected with HLA-DR genes to present antigen. Responses to two of the five determinants by T cell lines and clones were shown to be specific for HPV-16 based on the lack of crossrecognition of the corresponding sequences of other known papillomavirus sequences (types la, 5,6b, 8,11, 18 and 33). The T cells raised against two of the other peptides cross-reacted with corresponding peptides from other strains to varying extents, depending on their structural homology. The implications of these results regarding the prevalence of HPV-16 infection in the population and the possible diagnostic role of these responses in papillomavirus infection is discussed.
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Analysis of human papillomavirus type 16 open reading frame E7 immortalizing function in rat embryo fibroblast cells
More LessThe E7 open reading frame of human papillomavirus type 16 (HPV-16) encodes a protein that can immortalize primary rat cells, cooperate with the ras oncoprotein to transform low passage rat cells and transform established rodent cells to anchorage independence. The immortalizing and cooperation functions have been investigated using a series of point mutations that introduce single amino acid changes into the E7 protein in two distinct regions. Certain mutations altering amino acids conserved between the E7 protein of genital HPV types, the adenovirus E1 a protein and simian virus 40 large T antigen abolished the ability of the E7 protein to immortalize or cooperate with ras in a focus forming assay. Mutations in a consensus sequence for a casein kinase II recognition site, which is also shared by E1a and large T, reduced immortalizing activity, but did not affect the ability to cooperate with ras. Single mutations disrupting cysteine motifs, which form putative zinc-binding sites in the second region, reduced the activity of the E7 protein, whereas double mutants, in which neither of the cysteine motifs remained intact, showed no or very low activity. The activity of the mutants in immortalization and cooperation assays was essentially the same as their transforming activities in NIH 3T3 cells. This indicates that these three functions of E7 map to overlapping domains which cannot be separated by these mutations in the region of E1a/large T homology or the cysteine motifs.
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Cross-linking studies show that herpes simplex virus type 1 glycoprotein C molecules are clustered in the membrane of infected cells
More LessChemical cross-linking using ethylene glycol succinimi- dyl succinate (EGS) and dithiobispropionimidate (DTBP) was performed to determine the association of herpes simplex virus type 1 glycoprotein C (HSV-1 gC) with its nearest neighbours. Human embryonic lung (HEL) cells were infected with HSV-1 strain KOS, treated with EGS, lysed with Nonidet P40, immuno- precipitated with monoclonal antibodies specific for gC, and analysed by SDS-PAGE. These analyses demonstrated the presence of cross-linked complexes that migrated with an apparent M r in the range 150000 to 260000. Two-dimensional SDS-PAGE (non-reduced and then reduced) analyses of HSV-1-infected HEL cells treated with the cleavable cross-linker DTBP demonstrated that molecules that comigrated with gC were the only components of these high M r complexes. Immunoelectroblot (Western blot) analyses using polyclonal rabbit antiserum specific for gC verified that the high M r complexes contained gC. These results indicated that gC molecules may be localized in the infected cell membrane as dimers.
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Lipoproteins of varicella-zoster virus
More LessHuman fibroblast cells infected with varicella-zoster virus (VZV) showed a slight increase in lipoprotein synthesis, with the production of two major viral lipoproteins, as detected by radioimmunoprecipitation (RIP). Three bands of M r 73000, 90000 and 97000 were identified as forms of the VZV gpl glycoprotein. All three incorporated both palmitic and myristic acid, and were shown by thin-layer chromatography to contain myristic, palmitic and stearic acids. A very strong band corresponding to 7000 M r, which may represent the product of VZV gene 49, was detected after RIP and in VZV-infected cells, and was shown to contain almost entirely myristic acid. Several minor bands were also detected. The possible functions of the lipoproteins are discussed.
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Molecular cloning and physical mapping of the DNA of bovine adenovirus serotype 4; study of the DNA homology among bovine, human and porcine adenoviruses
More LessThe DNA of bovine adenovirus (BAV) serotype 4, a member of the subgroup 2 BA Vs, has been cloned and mapped with 11 restriction enzymes. Southern blot hybridizations probed by a clone containing about 50% of the BAV-4 genome revealed a very strong and extended DNA sequence homology amongst the members of subgroup 2, but no homology was detectable to the subgroup 1 bovine, or any of those human (HAV) and porcine adenovirus serotypes examined. These findings were strengthened by reciprocal hybridizations. When using the cloned hexon gene region of BAV-3 (subgroup 1) or the total genome of HAV-2 as probes, again no homology could be shown to the bovine subgroup 2 serotypes. The extent of DNA homology detectable between the members of bovine subgroup 1, the porcine and the human serotypes was variable, but in general less expressed than that observed within the bovine subgroup 2.
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Cloning and expression of an immunodominant region of the hepatitis delta antigen
More LessA cDNA clone prepared from hepatitis delta virus (HDV) RNA extracted from human serum was subcloned in the bacterial expression vector pPL31 to produce a fusion protein consisting of the first 98 amino acids of MS2 polymerase and of 64 amino acids from near the N-terminal region of hepatitis delta antigen (HDAg). The fusion protein was shown to be related to HDAg by a commercial sandwich immunoassay (Abbott) and immunoblotting with human anti- HDAg serum. Antiserum against the fusion protein was raised in rabbits and used to identify HDAg extracted from the serum and liver of an HDV-infected woodchuck and chimpanzee and from the serum of an HDV-infected human, by immunoblotting and immunohistology. A single, major polypeptide of 24K was detected in both serum and liver extracts, with a minor polypeptide of 26K sometimes present. Liver extracts also contained lower M r polypeptides thought to be degradation products, the major species being 22·5K. The same pattern of staining was obtained with human anti-HDAg serum. Absorption experiments with the expressed protein and cross-competition experiments with the rabbit antiserum suggest that a major immunodominant region of HDAg is present near the N-terminal end of the antigen, between positions 1561 and 1368 on the genome. Both the expressed protein and rabbit antiserum were shown to be good diagnostic reagents.
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Production of interleukin 1 and tumour necrosis factor activities in bronchoalveolar washings following infection of mice by influenza virus
More LessMice were infected with influenza A virus by aerosol. Bronchoalveolar washings obtained from infected mice contained interleukin 1 (IL-1) and tumour necrosis factor (TNF) activities. IL-1 was present at day 4 postinfection but not at day 7. TNF activity was present at day 4 and day 7 post-infection. The presence of both these monokines was coincident with increased cell populations in the lungs. In vitro studies demonstrated that macrophages from non-infected mice produce IL- 1 and TNF activities in response to live influenza A virus stimulation. These results suggest that a direct interaction between virus and alveolar macrophages leads to IL-I and TNF production during the course of infection and could account for both the immune responses and the pathology that occur during influenza A virus infection.
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Sequence comparison of the phosphoprotein mRNAs of antigenic subgroups A and B of human respiratory syncytial virus identifies a highly divergent domain in the predicted protein
More LessThe sequences of the P mRNA and protein of strain 18537 of antigenic subgroup B of human respiratory syncytial virus were determined by sequencing cloned cDNAs of intracellular mRNA. Comparison with the corresponding sequences of the A2 strain of subgroup A showed that there was extensive sequence identity at both the nucleotide (80% identity) and amino acid (90% identity) levels. The P proteins contained a single divergent region (52% amino acid identity) flanked by highly conserved domains (96% identity). The previously observed differences in electrophoretic mobilities between the P proteins of subgroup A strains and certain subgroup B strains could not be attributed to differences in the polypeptide Mr of the primary translation product.
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Nucleotide sequence of the glycoprotein S gene of bovine enteric coronavirus and comparison with the S proteins of two mouse hepatitis virus strains
More LessThe gene encoding the spike glycoprotein (S) of bovine enteric coronavirus (BECV) was cloned and its complete sequence of 4092 nucleotides was determined. This sequence contained a single long open reading frame with a coding capacity of 1363 amino acids (Mr 150747). The predicted protein had 19 N-glycosylation sites. A signal sequence comprising 17 amino acids was observed starting from the first methionine residue. A potential peptidase cleavage site was located between amino acids 763 and 767. These cleavages explain the maturation of the primary product of the S gene to SI (Mr 104692) and S2 (Mr 84175) spike structural proteins. Two amphipathic α-helices (amino acids 1007 to 1077 and 1269 to 1294) which may constitute the 12 nm stalk of the viral spike were also observed; another a-helix (amino acids 1305 to 1335) may be involved in the anchorage of the spike in the viral membrane. Comparison of this protein sequence to the described homologous mouse hepatitis (MHV) strain A59 and MHV-JHM S protein sequences led us to suggest that MHV-A59 and MHV-JHM S genes could be derived from a deletion of the BECV S gene.
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Analysis of linkage between scrapie incubation period and the prion protein gene in mice
More LessA single gene is known to have a predominant influence on scrapie incubation period in mice. In crosses between strains that give a short incubation period, such as NZW mice, and those which give a long incubation period, such as I/LnJ mice, long incubation period was dominant using a Chandler scrapie agent isolate. Recently a close linkage was found between the incubation period gene and the prion protein (PrP) structural gene in I/LnJ mice crossed to NZW mice. Because this linkage suggested an important role for PrP in the pathogenesis of scrapie we sought to verify the linkage between these genes and extended the analysis to three additional mouse strains. All four of the mouse strains that we evaluated, I/LnJ, P/J, MA/MyJ, and RIIIS/J, had incubation periods longer than those of the NZW mice to which they were crossed. In addition, all four strains shared an XbaI restriction enzyme polymorphism, which suggested that all four strains might also exhibit linkage between the incubation period and the PrP structural gene. Very strong linkage between PrP and incubation period was found in I/LnJ and P/J mice crossed to NZW mice, whereas less obvious linkage was demonstrated for MA/MyJ mice crossed to NZW mice. In MA/MyJ mice genes other than PrP also had an obvious influence on incubation period. In RIIIS/J mice no linkage was shown. Although linkage between PrP and incubation period was very significant in I/LnJ and P/J mice, a few animals were identified in both crosses that represented potential recombinants in which PrP and incubation period did not segregate together. Therefore, although these phenotypes are certainly linked in I/LnJ and P/J mice, it is possible that PrP and incubation period are controlled by separate genes.
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- Plant
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Molecular characterization of alfalfa cryptic virus 1
More LessAlfalfa cryptic virus 1 (ACV1) was purified from alfalfa plant clone (Medicago sativa) and characterized. The genome of ACV 1 consists of two dsRNAs, one with an estimated Mr of 1·27 × 106 (RNA 1) and the other of Mr 1·17 × 106 (RNA 2); the virus capsid is built from one polypeptide of estimated Mr 54000. An RNA- dependent RNA polymerase able to replicate the genomic RNAs in vitro is associated with purified virus particles. In vitro translation showed that each of the genomic RNAs encodes a polypeptide and that encoded by RNA 2 is the capsid protein. These polypeptides account for about 95 % and 83 % of the coding capacity of RNA 1 and RNA 2, respectively. In Western and Northern blot experiments close affinity was found between ACV 1 and hop trefoil cryptic virus 1, a cryptovirus found in Medicago lupulina. No affinity was detected with any other cryptovirus tested.
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In vitro messenger properties of a satellite RNA of cucumber mosaic virus
More LessThe nucleotide sequence of a naturally occurring satellite RNA (satRNA) of cucumber mosaic virus strain F (CMV-F) isolated from Petasites japonicum Miq. has been determined. F-satRNA is 338 nucleotides long and possesses a single open reading frame (ORF; residues 11 to 91) in its 5′-terminal region. Analysis of in vitro translation products of the RNA revealed that the major peptide synthesized had an M t of 2800, corresponding to the value (M r 2874) calculated from the amino acid sequence predicted from the ORF. Furthermore, a ribosome-binding fragment of the RNA in the initiation step of an in vitro translation system was found to contain the first AUG codon (residues 11 to 13). These results suggest that of the F-satRNA sequence, the coding region for the peptide can be assigned to the region from AUG to GGU (residues 11 to 91), accompanied by a termination codon UGA.
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In vitro translation of the citrus tristeza virus coat protein from a 0.8 kbp double-stranded RNA segment
More LessSeveral dsRNA segments, ranging in size from 0·8 to 19·5 kbp, have been isolated from citrus plants infected with the VT and ST strains of citrus tristeza virus (CTV) and translated, after denaturation, in a reticulocyte lysate cell-free system. Only two small dsRNA segments of 0·8 and 1·7 kbp were efficiently translated and showed a consistent pattern of products. The major translation product of the 0·8 kbp dsRNA was a 27K polypeptide, immunoprecipitated by antiserum to the CTV coat protein. The major translation product of the 1·7 kbp dsRNA segment was a 21·5K peptide. The possibility that the CTV coat protein may be translated from a subgenomic viral messenger RNA is discussed.
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- Corrigenda
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