ISOLATION OF A NEWLY IDENTIFIED EQUINE RESPIRATORY VIRUS.
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Animals↗
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The Marek's disease virus (MDV) unique short region: alphaherpesvirus-homologous, fowlpox virus-homologous, and MDV-specific genes.
Despite its previous classification as a gammaherpesvirus, primarily due to its lymphotropism, Marek's disease virus (MDV), an oncogenic avian herpesvirus, is phylogenetically more related to the "neurotropic" alphaherpesviruses, characterized by its prototype, herpes simplex virus (HSV) (Buckmaster et al., 1988, J. Gen. Virol. 69, 2033-2042). In this report we present the DNA sequence of an 11,286-bp DNA segment encompassing the entire 11,160-bp-long Us region of the oncogenic avian herpesvirus, Marek's disease virus. Eleven open reading frames (ORFs) likely to code for proteins were identified; of these, 7 represent homologs exclusive to alphaherpesvirus S component genes. These include MDV counterparts of HSV US1 (ICP22), US2, US3 (a serine-threonine protein kinase), US6, US7, and US8 (HSV glycoproteins gD, gI, and gE, respectively), and US10. Three additional ORFs were identified with no apparent relation to any sequences currently present in the SwissProt or GenBank/EMBL databases, while a fourth was found to exhibit significant homology to an uncharacterized fowlpox virus (FPV) ORF. Having precisely identified the IRs-U(s) and U(s)-TRs junctions, we have corrected and clarified their previously reported locations. By characterizing genes encoding three new alphaherpesvirus-related homologs (US1, US8, and US10), completing the sequence for a fourth (US7), and identifying 2 new MDV-specific ORFs (SORF1 and SORF3) and a fowlpox homolog (SORF2), our sequence analysis of the "virulent" GA strain of MDV (vMDV) extends upon that of a 5255-bp segment located in the U(s) region of the "very virulent" RB1B strain of MDV (vvMDV) (Ross et al., 1991, J. Gen. Virol. 72, 939-947; 949-954). These two sequences were found to exhibit 99% identity at both nucleotide and predicted amino acid levels. Combined with the fact that MDV U(s) sequences failed to show statistically significant CpG deficiencies, our analysis is consistent with MDV bearing a closer phylogenetic relation to alphaherpesviruses than to gammaherpesviruses. Because alphaherpesvirus-specific U(s) region genes are primarily nonessential for virus replication, they are thought to be important biological property determinants. Thus, our sequence provides a foundation for further MDV studies aimed at resolving the apparent discrepancy between MDV's genetic and biologic properties.
Amino Acid Sequence↗
Bluetongue virus: some relationships among North American isolates and further comparisons with EHD virus.
Seven isolates of bluetongue virus with different isolation histories and one isolate of the virus of epizootic hemorrhagic disease of deer were cloned by three consecutive plaquings in L-929 cells. The isolates were categorized on plaque size and margin. Antisera to the bluetongue virus isolates were produced in calves and antiserum to epizootic hemorrhagic disease virus in deer. Plaque reduction neutralization tests were done using the eight isolates and antisera to six of these. The isolates could be partially categorized on plaque type. In the plaque reduction neutralization test, all of the bluetongue viruses cross reacted and although differences were frequently observed, no obvious antigenic classification was possible. Reactions between the bluetongue viruses and epizootic hemorrhagic disease virus were all within the limits of what is presently considered to be non-specific inhibition.
Animals↗
Distinction of influenza viruses of different host cell origin.
Influenza A viruses grown in different animal or human cells retain their antigenic make-up as tested by the usual immunological assays. With the aid of a Sambucus nigra (L.) extract containing its lectins the viruses can be distinguished after one single passage in a different cell type by a change in their hemagglutinating properties. Binding of such lectins to influenza viruses may be a means for a more subtle classification, relating to the host cell origin of the virus.
Animals↗
THE PROPERTIES AND CLASSIFICATION OF TWO NEW RHINOVIRUSES RECOVERED FROM HORSES IN TORONTO, CANADA.
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Animals↗
Identification of a new Venezuelan equine encephalitis virus from Brazil.
Two strains of recently isolated Venezuelan equine encephalitis (VEE) complex virus from southern Brazil, avirulent for 6- to 8-week-old mice and short-haired guinea pigs, were characterized by biologic, serologic, and biochemical means. They were shown serologically to represent a single, newly recognized variant of subtype I. Two-dimensional polyacrylamide gel electrophoresis (PAGE) of ribonuclease T1 digests of viral ribonucleic acid showed considerable homology between the genomes of the new variant prototype and variant IA. Three structural proteins were visualized by discontinuous sodium dodecyl sulfate-PAGE (SDS-PAGE). Although the smallest protein of both recent isolates migrates with the capsid proteins of other subtype I viruses, the larger structural proteins of the new variants differ in molecular weight from the E1 and E2 envelope glycoproteins of the other subtype I variants. The new isolates produced peptide fragment patterns that were identical to each other, but different from the patterns of other subtype I viruses, following SDS-PaGE of dissociated virions digested with Staphylococcus aureus V8 protease. Since these two isolates were from Culex (Melanoconion) species mosquitoes and from a bat (Carollia perspicillata), were postulated that this is an enzootic VEE virus variant for which the classification IF is suggested.
Animals↗
NS 1 gene sequences from eight dengue-2 viruses and their evolutionary relationships with other dengue-2 viruses.
The nucleotide sequences of the NS 1 genes from five Thai and three Sri Lankan dengue-2 viruses were determined by sequencing the viral RNA using synthetic oligonucleotide primers. The results were shown to be similar to four published dengue-2 NS 1 sequences and the classification of these genes was compared with the one obtained for the envelope genes of the same viruses. The classification was similar and showed that the Thai isolates could be divided into two separate groups and that the Sri Lankan isolates were distinct. We found no correlation between disease severity, serological response (1 degree or 2 degrees), or year of isolation and various aspects of NS 1 protein sequence variation; and no particular amino acid changes were correlated with virulence. The sequences were combined with those published and classified elsewhere to provide a comprehensive E/NS 1 gene taxonomy of dengue-2 virus isolates.
Adolescent↗
[Urethro-adnexitis in the man and acute urethral syndrome in the woman. Microbiological and immunologic studies of etiologic classification].
Both common pathogens and unconventional, fastidious bacteria, viruses, parasites, and fungi are causative agents in male urethro-adnexitis and in female acute urethral syndrome. Uropathogens, Neisseria gonorrhoeae, Treponema pallidum, Mycobacterium tuberculosis, Chlamydia trachomatis, Mycoplasma spp., Haemophilus ducreyi, Calymmatobacterium granulomatis, Gardnerella vaginalis, anaerobic bacteria, Herpes simplex virus type II (HSV II), papillomaviruses (HPV), Trichomonas vaginalis and Candida spp. must be considered. The various diagnostic procedures and criteria applied for aetiological classification in cases of balanitis, urethritis, prostatitis, epididymitis, orchitis, and acute urethral syndrome are reviewed and evaluated.
Acute Disease↗
Parkville virus: a novel genetic variant of human calicivirus in the Sapporo virus clade, associated with an outbreak of gastroenteritis in adults.
This report describes the characterization of Parkville virus, the etiologic agent of an outbreak of foodborne gastroenteritis, that has the morphology of a calicivirus and genetic properties that distinguish it from previously identified strains in the Sapporo/Manchester virus clade. Sequence analysis of the Parkville virus genome showed it contained the RNA-dependent RNA polymerase motifs GLPSG and YGDD characteristic of members of the family Caliciviridae with an organization identical to that reported for the Manchester virus where the capsid region of the polyprotein is fused to the RNA polymerase. Parkville virus however, demonstrates considerable sequence divergence from both the Manchester and Sapporo caliciviruses, providing the first indications that genetic diversity exists within caliciviruses of this previously homogeneous clade. On the basis of recent advances in the genetic characterization of members of the family Caliciviridae, we propose a new interim phylogenetic classification system in which Parkville virus would be included with Manchester and Sapporo virus as a separate group distinct from the small round-structured viruses (Norwalk-like viruses) that also cause diarrhea in humans.
Adult↗
Molecular variation, evolution and geographical distribution of louping ill virus.
Following the demonstration that the tick-borne encephalitis (TBE) subgroup viruses are distributed as a cline across the Northern Hemisphere (Zanotto et al., 1995), we have analyzed the dispersal pattern of louping ill (LI) virus, the most westerly located member in the cline. A total number of 21 LI or LI-related virus E gene sequences have been used for a detailed molecular analysis of the evolution, phylogeny and geographical distribution of LI virus in the British Isles and Ireland. The results show that LI virus is genetically stable in general but minor differences enable its separation into four genetically distinct subtypes (genotypes) with clear geographical correlation, designated Type 1 in Scotland and England, Type 2 in Scotland, Type 3 in Wales and Type 4 in Ireland. These data demonstrate that geographically independent evolution of LI viruses has occurred. The molecular systematics and substitutional parameters analyses combined with the clinal distribution of the TBE virus complex allow the assignment of the origin for both Negishi (NEG) virus and a Norwegian isolate to the British Isles. Moreover, proposals for the classification of LI and LI-like viruses which cause encephalomyelitis in sheep, goat or cattle are presented.
Animals↗
International Committee on Taxonomy of Viruses (ICTV) activity report.
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Classification↗
[Seroprevalence of hepatitis C in human immunodeficiency virus infected patients].
Prevalence of antibodies against hepatitis C virus (HCV) was evaluated using Ortho and Abbott HCV Elisa assays and the Abbott EIA Neutralization assay in 150 human immunodeficiency virus (HIV)-seropositive patients and compared with the prevalence of hepatitis B virus (HBV) and hepatitis D virus (HDV) markers. Overall prevalence of hepatitis C virus antibodies was 29.3%; significant variations were seen across human immunodeficiency virus risk factor subgroups: prevalence was 10.2% in homosexual men, 12.0% in bisexual men, 73.5% in intravenous drug users, 13.3% in blood transfusion recipients, and 16.6% in frequent travellers. Seroprevalence was higher in the 20 to 40 year-old age group and in patients stage II or III according to the Center for Disease Control classification. Prevalence of hepatitis B virus and hepatitis D virus markers (75.7% and 17.5% respectively) was analyzed according to hepatitis C virus marker status; patients with HBcAb were more likely to have antibodies against hepatitis C virus than their HBcAb-negative counterparts. Further studies are needed to investigate the influence of coexposure to human immunodeficiency virus and hepatitis C virus on liver lesions. Data from this study show that coinfection or coexposure is common.
Adult↗
[Virus carriers: analysis of states of equilibrium between the virus and its host].
The various mechanisms of virus persistence are described. Four kinds of virus persistence are presented, depending on their epidemiological significance, persistence associated with continuous multiplication and transmission (feline calicivirus, calf rotavirus); persistence associated with continuous multiplication but discontinuous transmission (equine infectious anemia retrovirus); persistence with continuous multiplication associated with immunotolerance (feline leukaemia retrovirus; mucosal disease pestivirus); latent carrier state with discontinuous transmission (feline and pigeon herpesvirus; infectious bovine rhinotracheitis herpesvirus). The classification of these kinds of virus persistence is based upon their epidemiological significance, even if the mechanisms allowing the persistence are completely different.
Animals↗
Phylogeny and evolution of papillomaviruses based on the E1 and E2 proteins.
Papillomaviridae are a family of small double-stranded DNA viruses that infect stratified squamous epithelia in vertebrates. Members of this family are causative agents of malignant tumours, such as cervical cancer while others are associated with benign proliferative lesions. So far, Papillomaviruses (PVs) are classified according to the sequence identity in the capsid gene L1. However, evidence has accumulated indicating a discontinuity in the evolutionary history of the L1 and L2 genes of many PVs, giving rise to differences in the phylogenetic reconstructions of the early and of the late genes. Neither the oncogenes E5, E6 and E7 nor the upstream regulatory region are suitable for phylogenetic inference due to the poor conservation along the Papillomaviridae family. We have analysed here the evolutionary relationships of the PVs with respect to the E1 and E2 proteins, and the results provide both phylogeny and biologic behaviour of the viruses. The hierarchical taxonomic relationships can be structured as an alternative classification system in which mucosal high-risk viruses, mucosal low-risk viruses and viruses associated with cutaneous lesions are grouped separately and do not appear intermingled. Some important trends are also observed: first, evolution of the PVs has not been homogeneous, even in viruses that infect the same host, and second mucosal human PVs have evolved faster than their cutaneous counterparts. The evolutionary analysis based on the E1 and E2 proteins will allow us to better understand the generation of the diversity of the PVs and the development of malignancy associated with these viruses.
Animals↗
Plaque production by arboviruses in Singh's Aedes albopictus cells.
We report plaquing tests of 124 virus strains, mostly arboviruses of 21 serological groups, in Singh's line of Aedes albopictus cells. Thirty of these plaqued: all were arboviruses of six groups and were known or presumed to be mosquito borne. Failing to plaque were 86 strains of arboviruses, mostly tick borne, two strains of insect pathogens, and six animal viruses not classified as arboviruses. Among mosquito-borne agents, plaquing ability appeared related to serological classification. California group and most A-group viruses failed to plaque, but nearly all members of B and Bunyamwera groups readily plaqued. Within serological group B, 14 of 16 mosquito-borne agents plaqued, but none of 13 tick-borne or vector-unassociated viruses did so. Some implications of these results for recognition and classification of arboviruses are discussed.
Aedes↗
Characterization and seroepidemiology of a type 5 astrovirus associated with an outbreak of gastroenteritis in Marin County, California.
The Marin County strain of type 5 astrovirus was associated with two separate outbreaks of nonbacterial gastroenteritis in California in 1978. A safety-tested, bacterium-free filtrate prepared from a stool specimen of an individual who was ill during the original outbreak was given orally to 19 adult volunteers. One volunteer developed a gastrointestinal illness, and nine had serologic responses. Several diarrheal stool specimens from the ill volunteer contained a large number of 27-nm particles. By using immune electron microscopy with acute- and convalescent-phase sera from the original outbreak, these 27-nm particles were shown to be identical to the viral inoculum. The Marin County virus, purified from the stool of the ill volunteer, was shown by immunoprecipitation and polyacrylamide gel electrophoresis to contain a single structural protein with a molecular weight of 30,000. The buoyant density of the virion was 1.39 g/cm3 in cesium chloride. By electron microscopy, approximately 5% of the particles had the characteristic stellate configuration of astrovirus, and serologic studies by immunofluorescence technique confirmed previous classification of the Marin County virus as a type 5 astrovirus. Radioimmunoassay and biotin-avidin immunoassay were used to detect antibody to the Marin County virus in paired acute- and convalescent-phase sera from 32 outbreaks of nonbacterial gastroenteritis, but none of these outbreaks could be attributed to this virus. Prevalence of antibody to this strain of astrovirus was approximately 13% in children 6 months to 3 years of age and increased to 41% in older children and young adults.
Acute Disease↗
Pathobiology of human papillomavirus.
Human papillomavirus (HPV) has long been recognized as the etiologic agent of skin and genital warts, and only recently has an oncogenic role been attributed to the virus. This article discusses the classification, genetics, and pathogenesis of HPV. HPV detection, epidemiology of HPV and cervical neoplasia, and HPV infections in the genital tract are also reviewed.
Condylomata Acuminata↗
The use of serological differentiation indices for the phylogenetic analysis of plant virus relationships.
The potential use of serological differentiation indices (SDIs) in the phylogenetic analysis of plant virus coat protein relationships is presented. Relationship dendrograms were constructed from SDI data for viruses in the tymovirus and Subgroup I geminivirus taxonomic groups, using distance or phenetic methods embodied in the computer programmes FITCH and NJTREE. Relationship dendrograms for geminiviruses agreed well with those constructed by others from sequence or other data; the dendrogram for tymoviruses was not in agreement with one calculated from amino acid composition data, or from other properties, but appears consistent with recently-shown sequence similarities between tymoviruses. Implications of these results for the classification and taxonomy of plant viruses are discussed.
Data Interpretation, Statistical↗