Showing papers in "Archives of virology. Supplementum in 1992"

Serology of potyviruses: current problems and some solutions.

Abstract: The serological relationships among members of the family Potyviridae are extremely complex and inconsistent. Variable cross-reactivity of polyclonal antisera, unexpected paired relationships between distinct viruses, and lack of cross-reactions between some strains are the major problems associated with the serology of potyviruses. Recent biochemical and immunochemical investigations of coat proteins have established the molecular basis for potyvirus serology and provided explanations for most of the problems with serology of potyviruses. Information from these studies has also formed the basis for the development of several novel approaches to the accurate detection and identification of potyviruses. However, even these novel approaches are not without drawbacks and some of them cannot be applied easily in plant virus laboratories, since they require prior sequence information and facilities for peptide synthesis. These findings suggest that serology is an imperfect criterion for the identification and classification of potyviruses.

Sequence data as the major criterion for potyvirus classification.

Abstract: Recent knowledge of the structure of the potyvirus particle and its components appears to have resolved what was thought to be an intractable problem of plant virology. This review describes how coat-protein and gene sequence data can be used to provide an hierarchical classification of potyviruses. This classification puts the aphid and non-aphid-transmitted potyviruses into a single family, divides this family into four genera that correspond to the four modes of vector transmission, discriminates distinct potyvirus species from strains, and provides a basis for the formation of subgroups composed of closely related species within a genus.

Sources of resistance to viruses in the Potyviridae

Abstract: Resistance to 56 viruses in the family Potyviridae in 334 plant species was tabulated. Studies conducted in the last 60 years have elucidated the genetics and usefulness of 135 resistance genes, but no reports on the heritability of other sources of resistance are available. In most of the plant species, resistance to species of Potyviridae was simply inherited, either dominantly (60 genes) or recessively (39 genes). In some cases resistance was conferred by two or more genes. Symbols have been assigned to 86 genes, of which very few are duplicate entities. Resistance genes can be useful in determining relationships among these viruses, as well as for their identification. The role of conventional breeding and biotechnology in transferring genes from one species to another is discussed.

Serotype A and B strains of bean common mosaic virus are two distinct potyviruses.

Abstract: The serological relationships among strains of bean common mosaic virus (BCMV) (genus Potyvirus, family Potyviridae) were investigated by testing 13 isolates of the 10 known BCMV pathotypes with two monoclonal antibodies and six antisera to BCMV strains. In addition, other properties of serologically distinct BCMV strains were compared. Two groups of BCMV strains were obtained by ELISA and Western blot serology: serotype A contained the BCMV strains NL3, NL5, and NL8 and serotype B contained the BCMV strains NL1, NL2, NL4, NL6, US4, NL7, NY 15, and Fla.SDS Polyacrylamide gel electrophoresis and Western blotting of freshly purified preparations, and of extracts from leaves infected with eleven BCMV strains showed that the apparent molecular mass of the capsid protein of the serotype A isolates NL3, NL5, and NL8 are lower (about Mr 33,000) than those of the serotype B isolates (Mr 34,500 to 35,000). The normal lengths of the particles of the serotype A isolates were shorter (810–818 nm) than those of most isolates (except NL6 and NY 15) of serotype B (847–886 nm). All isolates studied induced cytoplasmic pinwheel and scroll inclusions. Cells infected with serotype A isolates contained a specific type of proliferated endoplasmic reticulum which was never found in cells infected with serotype B isolates. The capsid protein gene of a representative member of each serotype was cloned and sequenced. Molecular mass calculations based upon nucleotide sequence-derived amino acid sequences yielded Mr of 29,662 and 32,489 for the capsid proteins of the serotype A isolate NL8 and the serotype B isolate NL4, respectively. Comparison of the coat-protein sequences showed considerable differences at the N-termini whereas the core regions and the C-termini appeared to be highly conserved. Marked differences were also observed within the 3′ non-coding regions of cloned cDNAs of NL 4 and NL 8. The striking differences between the two serotypes of BCMV strongly suggest that they be classified as two distinct potyviruses which naturally infect Phaseolus beans.

Present status of the sugarcane mosaic subgroup of potyviruses.

Abstract: Until recently, sugarcane mosaic virus (SCMV) was believed to be a single potyvirus consisting of a large number of strains, differing from each other in certain biological and antigenic properties. The use of affinity-purified polyclonal antibodies directed towards the surface-located, virus-specific amino termini of the coat proteins showed that 17 strains from Australia and the United States represented four distinct potyviruses, namely johnsongrass mosaic virus (JGMV), maize dwarf mosaic virus (MDMV), sorghum mosaic virus (SrMV) and SCMV. Comparisons of strains from each of these four viruses on the basis of reactions on differential sorghum and oat cultivars, cell-free translation of RNAs, morphology and serology of cytoplasmic cylindrical inclusions, amino acid sequence and peptide profiling of coat proteins, 3′ non-coding nucleotide sequences, and molecular hybridization with probes corresponding to the 3′ non-coding regions, resulted in exactly the same taxonomie assignments as obtained using amino-terminal serology. These results further confirm that the former sugarcane mosaic virus actually consists of four distinct viruses and show that MDMV, SrMV, and SCMV are more closely related to each other than they are to JGMV. Because these four viruses are closely related but distinct, formation of a sugarcane mosaic subgroup in the genus Potyvirus would be appropriate.

Coat protein phylogeny and systematics of potyviruses.

Abstract: The feasibility of applying molecular phylogenetic methods of analysis to aligned coat-protein sequences and other molecular data derived from coat proteins or genomic sequences of members of the proposed taxonomie family Potyviridae, is discussed. We show that comparative sequence analysis of whole coat-protein sequences may be used reliably to differentiate between sequences of closely related strains, and to show groupings of more distantly related viruses; that coat proteins of putative Potyviridae cluster according to the proposed generic divisions, and, even if some are only very distantly related, the members of the family form a cluster distinct from coat proteins of other filamentous and rod-shaped viruses. Taxonomie revisions based on perceived evolutionary relationships, and the lack of feasibility of erecting higher taxa for these viruses, are discussed.

Serological and biological relationships among viruses in the bean common mosaic virus subgroup.

Abstract: Bean common mosaic virus (BCMV), blackeye cowpea mosaic virus (B1CMV), cowpea aphid-borne mosaic virus (CABMV), azuki bean mosaic virus (AzMV), and peanut stripe virus (PStV) are five species of the genus Potyvirus, family Potyviridae which are seed-transmitted in beans or cowpeas. Eighteen isolates of BCMV, five isolates of B1CMV, four isolates of CABMV, and one isolate each of AzMV, and PStV were compared serologically using a panel of 13 monoclonal antibodies (MAbs) raised against BCMV, B1CMV, CABMV, or PStV in indirect enzyme-linked immunosorbent assay (ELISA). Four MAbs detected all virus isolates; one detected all isolates except those of CABMV. Three MAbs were specific only for serotype A isolates of BCMV Four MAbs detected all serotype B isolates of BCMV plus all isolates of B1CMV, AzMV, and PStV. None of the antibodies distinguished among these four viruses. However, in biological tests with 11 bean cultivars selected for differentiating BCMV pathotypes, all isolates of B1CMV, AzMV, and PStV could be differentiated from the BCMV serotype B isolates by their reactions on a few bean cultivars in host group I and the cowpea cultivar California Blackeye #5. Potential problems that can arise from the use of nonauthenticated isolates are also discussed.

The general properties of potyviruses.

Abstract: The criteria used during the past three decades for including viruses in the potyvirus group are briefly discussed and evaluated. The biological and physico-chemical properties of the viruses transmitted by aphids, mites, whiteflies, or the fungus Polymyxa graminis are reviewed, and the taxonomic value of their molecular properties in regrouping the viruses into four groups or genera within the family Potyviridae is discussed.

Potyviruses, monoclonal antibodies, and antigenic sites.

Abstract: Virus-specific and cross-reactive monoclonal antibodies have been produced to at least 19 different aphid-transmitted potyviruses. This report summarizes the development of these monoclonal antibodies as well as presents information on the delineation of the virus-specific and group-common epitopes defined by these monoclonal antibodies. Virus-specific and group-common antigenic determinants were mapped by a variety of techniques, including analysis of antigen: antibody reactivity patterns, determination of N-terminal vs. trypsin-resistant core peptide-specificity, immuno-analysis of overlapping synthetic peptides, and immunoanalysis of bacterially expressed coat-protein gene products. Of those monoclonal antibodies that have been examined, monoclonal antibody-defined virus-specific epitopes are virion surface-located within the 30+ amino acid amino terminus, whereas the group-common epitopes are found in the trypsin-resistant core protein not usually located on the virion surface, as has been shown previously with certain polyclonal antibodies. New information is presented on the analysis of bean yellow mosaic virus amino terminal epitopes as well as on the identification of amino terminal antigenic determinants shared between strains of bean yellow mosaic virus and pepper mottle virus. A recommendation on the evaluation and use of a panel of potyvirus broad-spectrum reacting monoclonal as reference monoclonal antibodies for the detection and classification of aphid-transmitted potyviruses is also presented.

A summary of potyvirus taxonomy and definitions.

Abstract: The current taxonomie status of the family Potyviridae is presented pathotype with suggestions for resolving some taxonomic problems. Terms such as strain, pathotype, serotype, variant, mutant, and isolate are dtscussed in relatton to the family.

Biological variability of potyviruses, an example: zucchini yellow mosaic virus.

Abstract: Potyviruses present an important variability which may affect biological properties such as host range, symptomatology, virulence towards resistance genes, and transmissibility by vectors A brief account of this potential is presented and illustrated by some aspects of the biological variability of zucchini yellow mosaic virus (ZYMV)

Functions of hepatitis B surface proteins.

Abstract: HBV surface proteins play a number of functional roles in cellular infection, viral synthesis and in immune responses of the host. Three coterminal proteins of differing sizes and three subdomains of the individual molecules can be recognized. In this brief review, functions of the various proteins and domains are described and their significance as potential immunogens is discussed. Although it is apparent that the surface proteins are involved in the development of persistent HBV infections, the underlying mechanisms of their involvement remain unknown.

Bean yellow mosaic virus subgroup; search for the group specific sequences in the 3' terminal region of the genome.

Abstract: In order to examine relationships among viruses of the bean yellow mosaic subgroup of the Potyvirus genus, several isolates of bean yellow mosaic virus (BYMV) and clover yellow vein virus (C1YVV) were compared by amino acid sequence of the coat protein and nucleotide sequence of the 3′ terminal non-coding region. The sequence comparisons showed that BYMV and C1YVV were distinct viruses but had close affinity to each other (85–95% homology among isolates of a virus but 70-77% homology between viruses), justifying establishment of the BYMV subgroup. There was an oligonucleotide consensus sequence present in the 3′ terminal non-coding region of all potyviruses examined. This consensus sequence divided the potyviruses into three groups whose significance is not clear.

Absence of free core antigen in anti-HBc negative viremic hepatitis B carriers

Abstract: Using enzyme immune assay and immune electron microscopy, we have examined the sera of immune-suppressed anti-HBc negative HBV-infected patients for the presence of HBcAg. Our results suggest that free HBV core particles are absent or present only in minute amounts in the blood of chronic carriers and that at the most, only minimal amounts of core antigen are found on the surface of the virus particles.

Application of genome sequence information in potyvirus taxonomy: an overview.

Abstract: The application of protein and nucleic acid sequence analysis in evolutionary and phylogenetic studies is well established. Available sequence information for the 5′ untranslated region of potyviruses including the fungus-transmitted barley yellow mosaic virus (BaYMV) RNA-1 suggests that a 12-nucleotide conserved sequence, the “potybox” is unique to this group. Various non-structural proteins of potyviruses share considerable “signature” sequence homology across a broad spectrum of unrelated viruses, which makes their value limited to “supergroup” or “superfamily” identity. However, in potyviruses, the coat-protein N-terminal sequences and 3′ noncoding regions are variable among viruses, but similar among strains of the same virus. This suggests that these sequences may be an accurate marker of genetic related-ness. Until complete genome sequences from a large number of potyviruses become available and their value in systematics is tested, coat protein and 3′ noncoding regions remain as the choice of taxonomic indicators. The reason being, that cloning and sequencing of the coat-protein gene and 3′ noncoding regions are less complicated and time consuming and the sequences show significant differences among the virus species within the family Potyviridae.

Differentiation of the four viruses of the sugarcane mosaic virus subgroup based on cytopathology.

Abstract: A cytological comparison has been made of representative isolates of johnsongrass mosaic (JGMV), maize dwarf mosaic (MDMV), sorghum mosaic (SrMV) and sugarcane mosaic (SCMV) viruses. These four viruses now encompass the complex of virus strains which were formerly considered as strains of sugarcane mosaic and/or maize dwarf mosaic viruses. The structure of the cytoplasmic cylindrical inclusions induced by these viruses, together with other cytological alterations, allow the four viruses to be distinguished. Pinwheels, scrolls and laminated aggregates were produced only by SCMV whereas JGMV, MDMV, and SrMV produced only pinwheels and scrolls. SrMV produced amorphous cytoplasmic inclusions which are not produced by JGMV and MDMV. The latter two were rather similar in cytological effects except that the SCMV-JG (U.S.A.) isolate of MDMV produced aggregates of needle-like structures in the cytoplasm which were not found with JGMV and the other MDMV isolates. The specific cytological effects induced by these viruses thus corroborate the recent classification of these viruses based mainly on the properties of the coat-protein gene, the 3′ non-coding nucleotide sequences, and host reactions.

Hepatitis C virus infection in patients with idiopathic hemochromatosis (IH) and porphyria cutanea tarda (PCT)

Abstract: The prevalence of HCV antibodies in IH and PCT patients was examined. It was found that both groups are characterized by increased incidence of HCV infection. These results suggest a possible connection between HCV and iron overload.

Strains of bean common mosaic virus consist of at least two distinct potyviruses.

Abstract: Bean common mosaic virus (BCMV) consists of a large number of pathotypes and strains which have largely been identified by their characteristic interactions with a selected number of differential bean cultivars. The relationships among these strains and other potyviruses that infect legumes are complex, with indications that BCMV, blackeye cowpea mosaic virus (B1CMV) and azuki bean mosaic virus (AzMV) may be strains of the one virus. Using high performance liquid chromatographic peptide profiles of coat-protein digests, the NL3 and NY 15 strains of BCMV were compared with each other, with the Type and W strains of B1CMV and with the mild mottle strain of peanut stripe virus (PStV). The results suggest that BCMV-NL3 and BCMV-NY15 are distinct potyviruses, not strains of the one virus, and that BCMV-NY15 is a strain of the same potyvirus that includes B1CMV, PStV, AzMV and three potyvirus isolates (74, PM, PN) from soybeans.

A proposal for a bean common mosaic subgroup of potyviruses.

Abstract: In order to elucidate the taxonomic positions of bean common mosaic virus (BCMV) and blackeye cowpea mosaic virus (B1CMV), several strains of these viruses were compared on the basis of host ranges, antigenic properties established with antisera to virions and to N-terminal peptide domains of their coat proteins, and high performance liquid chromatographic peptide profiles The comparison includes three strains of BCMV, viz NL1, NL3 and NY15, four strains of B1CMV, viz Fla, Ind, NR, and W, and the Moroccan isolate (Mor) of cowpea aphid-borne mosaic virus (CABMV), formerly designated as BICMV-Mor Based on these parameters, Fla, NR, and W are strains of one virus, whereas NL3, Ind and CABMV-Mor (and possibly NL1 and NY 15) are separate viruses In view of these characteristics which allow similar viruses to be separated, we propose that these viruses be included in a bean common mosaic subgroup of the genus Potyvirus

Potyviridae: genus Rymovirus.

Abstract: The genus Rymovirus of the family Potyviridae is comprised of seven rod-shaped viruses with the shared characteristic of being transmitted by mites. Aside from this distinguishing feature, rymoviruses are similar to aphid-transmitted potyviruses in that they share a similar particle morphology, some similar antigenic determinants, similar physico-chemical properties, the ability to induce the formation of cytoplasmic cylindrical inclusions, and the ability to infect only graminaceous hosts. In vitro translation studies with wheat streak mosaic virus (WSMV) suggest that this rymovirus uses a potyviral proteolytic processing strategy to express the 3′ terminal capsid protein. At the molecular level, limited nucleotide sequence data for WSMV show similarities with aphid-transmitted potyviruses in the potyviral capsid protein, large nuclear inclusion and cylindrical inclusion regions. Thus, given the similarities between the rymoviruses and the potyviruses, it is appropriate to include this genus within the family Potyviridae.

Potyviruses, chaos or order?

Abstract: At first potyviruses were easily distinguished by biological and serological properties because only a few were known and information on their host ranges was limited. The first evidence of serological cross reaction between two of these viruses was reported in 1951 and was further corroborated for three obviously distinct members of the group in 1960. In 1968 attention was drawn to the fact that some legume and non-legume potyviruses have much wider host ranges than previously known and that within the potyvirus group there is as much biological variation within viruses and overlap between viruses as there is in serology. The concept of continuity within the group was soon supported by others and became known as the “continuum hypothesis.” Results with highly sensitive serological methods using polyclonal antisera were conflicting, and nucleic acid hybridization techniques did not unambiguously discriminate between potyviruses.

The hepatitis B virus X protein transactivation of c-fos and c-myc proto-oncogenes is mediated by multiple transcription factors.

Abstract: We have constructed two expression vectors in order to study the action of the HBV 17 Kd X protein on the c-fos and c-myc promoters. The results show that the promoters contain multiple elements that respond to X protein, suggesting involvement of multiple transcription factors. The exact mechanism of the interaction remains elusive, but our data allow speculation about the factors that may be influenced.

Evidence that pepper mottle virus and potato virus Y are distinct viruses: analyses of the coat protein and 3′ untranslated sequence of a California isolate of pepper mottle virus

Abstract: Pepper mottle virus (PepMoV) is a member of the large and complex genus Potyvirus, and is classically distinguished from other members of the genus by differential host range and cytopathology as well as serology of the coat protein and cytoplasmic inclusion body proteins. Here we report the deduced amino acid sequence of the coat protein of a California potyvirus identified by a variety of classical methods as PepMoV (PepMoV C). Comparison of the 3′ untranslated nucleic acid sequence and the deduced coat-protein amino acid sequence of the PepMoV C isolate with those of PVY and other potyviruses indicates that PepMoV C is sufficiently diverged to be considered a distinct virus species. Thus, comparative sequence analyses of the PepMoV C isolate support earlier serological and biological evidence that PepMoV and PVY are distinct viruses.

Comparative molecular biology of flaviviruses and hepatitis C virus.

Abstract: Currently available sequence information suggests that the genome organization of hepatitis C virus is similar to that of flaviviruses. A positive-stranded genomic RNA contains a single long open reading frame (ORF) which is flanked by 5′ and 3′ noncoding sequences. This RNA codes for structural proteins at the 5′ end (starting with the capsid protein) and a set of nonstructural proteins in the remainder of the genome. The latter provide essential virus-specific functions for the viral life cycle, such as protease, helicase, and RNA replicase activities. The sequence motifs characteristic of the corresponding functional protein domains are separated by similar spacings in the nonstructural regions of hepatitis C virus and flaviviruses. The structural region of the hepatitis C virus appears to consist of a capsid protein which is larger than that of flaviviruses and two putative envelope proteins which are presumably different in molecular weight and much more heavily glycosylated than their counterparts in flaviviruses. A study group of the International Committee on the Taxonomy of viruses proposes to include hepatitis C virus as a genus into the family ‘flaviviridae’.

Properties of a recombinant yeast-derived hepatitis B surface antigen containing S, preS2 and preSl antigenic domains

Abstract: Yeast cells have been engineered to express mixed HBsAg particles containing the S and a modified large (L*) protein. Their construc¬tion resulted in reduced protease sensitivity, reduced glycosylation and complete inactivation of the polymerized human albumin binding site. The particles exposed the S, preSl and preS2 antigenic determinants and induced an immune response against the three domains. Highly purified preparations have been obtained and are presently being tested in human volunteers.

The recombinative nature of potyviruses: implications for setting up true phylogenetic taxonomy.

Abstract: Sequence comparisons reveal that positive-strand RNA viruses not only evolve by divergence from common ancestors but also by interviral recombination A considerable number of these viruses, exemplified by the family Potyviridae, can in fact, be regarded as successful products of a number of recombination events It is concluded that the recombinative character of RNA viruses will hamper any attempt to set up a true phylogenetic taxonomy It is advisable, therefore, to avoid the introduction of any taxon higher-than-family in virus taxonomy

HBV and HCV infection in i.v. drug addicts; coinfection with HIV.

Abstract: A group of 122 drug addict patients were studied to evaluate the incidence of HIV, HBV, HCV infections and of laboratory findings of hepatic damage. Our data show that hepatic damage is more frequent in patients affected by HBV-HCV coinfection than those with HBV or HCV infection alone and that HIV positivity supports HBV-HCV coinfection.

Fine specificity of the human T cell response to hepatitis B virus core antigen.

Abstract: The fine specificity of the human T cell response to the hepatitis B virus core antigen (HBcAg) was investigated in 23 patients with acute hepatitis B virus (HBV) infection using a panel of short synthetic peptides covering the entire core region. An immunodominant T cell epitope which was recognized by all except one patient, was identified within the core sequence 50-69. Two further important T cell recognition sites were represented by the amino acid sequences 1-20 and 117-131, which were stimulatory for the T cells of 69% and 73% of the patients, respectively. T cell recognition of the synthetic peptides was HLA class II restricted because the peptide-induced T cell proliferation was inhibited by anti-HLA class II but not by anti-HLA class I monoclonal antibodies. These findings may be relevant to the development of future preventive and therapeutic strategies against HBV infection.

Immune pathogenesis of hepatitis A.

Abstract: In an effort to elucidate the mechanism of liver damage resulting from Hepatitis A virus (HAV) infection, we have studied infected skin fibroblasts and autologous lymphocytes from HAV patients. We report here that HLA-restricted virus-specific T cells play an essential role in HAV-related hepatocellular injury.

PCR detection of HCV RNA among French non-A, non-B hepatitis patients.

Abstract: Hepatitis C virus (HCV) cDNA was amplified from serum of 26/40 French chronic non-A, non-B hepatitis patients by the nested polymerase chain reaction Compared with anti-C100, viral cDNA represents a more reliable marker of active HCV replication