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At least 127 records · Page 7Linked to original sources
PubMed1997

[Sequence analysis of 5' non-coding region of hepatitis G viruses and preliminary classification of genotypes].

For analyzing the structural characteristics of hepatitis G virus (HGV or GBV-C), 277 nucleic acids of 5' non-coding region of HGV were amplified using PCR from the sera of 2 paid donors, 2 chronic hepatitis patients and 2 patients with liver cirrohsis. The products were cloned and sequenced. The data were analyzed with the computer programs. The results indicated that the gene sequence homologies among 6 HGV isolates (G001-G006) obtained in this study were above 96.2%. The comparison of these 6 isolates and 3 foreign isolates reported previously showed that the sequence homologies were in the range from 86.9% to 91.6%. According to the variability of gene sequences, the preliminary division of genotypes of 6 Chinese HGV isolates (G001-G006) and 3 isolates reported abroad were classified into three distinct groups. The results suggest that the gene sequences of Chinese HGV isolates are highly homologous but have an obvious divergence with the foreign isolates. The 5' untranslated regions of all isolates analyzed probably contain a stable and similar secondary structure.

5' Untranslated Regions↗
PubMedDate not supplied

Micro neuraminidase-inhibition assay for classification of influenza A virus neuraminidases.

A neuraminidase-inhibition (NI) assay performed in microtiter plates is described. This micro-NI assay is a modification of the NI assay recommended by the World Health Organization. It reduces the quantity of reagents required and permits antigenic classification of many isolates simultaneously. To determine the accuracy and sensitivity of this micro-NI assay, 110 influenza A viruses, representing all subtypes, based upon the nine known neuraminidases (NAs), were classified by both the micro-NI and macro-NI assays in two separate laboratories. The NAs were identified accurately by the micro-NI assay. Virus mixtures were detected by both assays, although the macro-NI was clearly more sensitive. The micro-NI assay was also suitable for testing sera for the presence of antibodies to the NAs. Although the micro-NI assay did not provide the quantitation of the macro-NI assay, it did prove to be a rapid method for virus classification and antibody studies on influenza A viruses.

Animals↗
PubMed1993

[Molecular evolutionary analysis of hepatitis B virus (HBV) and genetic classification].

HBsAg of Hepatitis B virus (HBV) has been classified into four major subtypes (adw, adr, ayw, ayr) by the serological methods. Using molecular evolutionary analysis technique, we constructed the phylogenetic tree for the partial S gene (HBsAg gene) of HBV. The tree shows that 51 strains of HBV can be classified into following four genetic subgroups: (1) strains of subtypes ayw and adyw, (2) those of adw and adr, (3) another of adw, and (4) other subgroup of adr, adw, ayr, ar and ad. We propose that these subgroups be designated gyw, gdw-1, gdw-2, and gdr, respectively, with "g" standing for genetic classification. It is important that the genetic classification of HBVs is not always compatible with conventional serological subtypes. It is possible that the conventional subtypes do not represent a classification according to the degree of genetic difference among strains of HBVs. Thus, our genetic classification is more suitable for studies of epidemiological and virological features of HBVs.

Amino Acid Sequence↗
PubMedDate not supplied

Neurology of AIDS virus infection: a clinical classification.

Infection with the AIDS virus itself (HIV, HTLV-III, LAV, ARV) is associated with a full spectrum of neurological disorders. The application of diagnostic studies for HTLV-III infection has demonstrated that these neurologic disorders can be the first manifestation of AIDS or occur in the absence of AIDS. The most common conditions associated with HTLV-III infection alone are a subacute encephalopathy (AIDS dementia) and peripheral neuropathy; however, vacuolar myelopathy and both acute and chronic aseptic meningitis are also common. Congenital (or neonatal) transmission of the virus can result in a mental retardation syndrome of delayed onset. The AIDS virus is neurotropic as well as targeting T-helper lymphocytes. The virus has been readily identified in neural tissues and cerebrospinal fluid, including instances in which other central nervous system infections, such as toxoplasmosis, coexist. Hence, recognition of an appropriate syndrome, neurodiagnostic studies, and exclusion (or treatment) of other infections, as well as evidence for HTLV-III infection are required for diagnosis. The development of successful therapy will require agents which cross the blood-brain barrier.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Classification of herpes simplex virus keratitis.

PURPOSE: We propose a nomenclature for classification of herpes simplex virus (HSV) keratitis. We hope that a more consistent classification system will lead to a better understanding of the disease processes, thus resulting in improved diagnosis, treatment, and patient outcomes. METHODS: A review of the literature was performed to evaluate current HSV classification systems. These systems were evaluated in the context of both current clinical and basic science studies and our own clinical observations. RESULTS: The proposed classification system is based on the anatomy and pathophysiology of the specific presentations of HSV keratitis. Anatomically, the primary level of corneal involvement, whether epithelium, stroma, or endothelium, must be elucidated. Pathophysiologically, the cause of the inflammation. whether immunologic, infectious, or neurotrophic, must be determined. There are four major categories of HSV keratitis. (1) Infectious epithelial keratitis, which is made up of cornea vesicles, dendritic ulcer, geographic ulcer, and marginal ulcer. (2) Neurotrophic keratopathy, which includes punctate epithelial erosions and neurotrophic ulcer. (3) Stromal keratitis, which is subdivided into necrotizing stromal keratitis and immune stromal keratitis. (4) Endotheliitis, which has three clinical presentations: disciform, diffuse, and linear. CONCLUSION: We believe that by categorizing cases of HSV keratitis by their primary anatomic and pathophysiologic etiologic characteristics, clinicians can better understand and therefore treat all types of HSV keratitis. The four main categories of HSV keratitis are infectious epithelial keratitis, neurotrophic keratopathy, stromal keratitis, and endotheliitis. Each of these is subdivided to more specific clinical presentations.

Cornea↗
PubMed2002

Phylogenetic classification of TT virus groups based on the N22 region is unreliable.

Evolutionary studies on the recently discovered TT virus (TTV) are currently focused on approximately 220 nts of the N22 region, since this is the region for which most sequence information is available. Regarding the extensive sequence heterogeneity in this region, within group classification can be sufficiently reliable, however, between group classification becomes problematic. We observed high divergence at the nucleotide level between distant related strains (TTV groups) preventing unambiguous alignments, saturation in transitions within TTV groups and considerable phylogenetic noise due to conflicting signals within distinct genotypes. Consequently, analysing all TTV groups in one tree, using this 220 nt region provides unreliable results. Also within genotype analysis can produce conflicting results. On the other hand, this region is still suitable to some extent for within TTV group phylogenetic analysis. We suggest that care should be taken in future TTV phylogenetic analysis, in particular, larger and more conserved regions should be sequenced to allow between group comparisons.

Genotype↗
PubMed1999

Classification of herpes simplex virus keratitis and anterior uveitis.

PURPOSE: To review the classification of herpes simplex virus (HSV) keratitis and anterior uveitis using the available clinical, pathologic, and laboratory models of disease. METHODS: The literature was reviewed to establish prior classifications of herpes simplex keratitis and uveitis. The author introduces a classification attempting to encompass all patients with this disease process, taking into account the newer proposed mechanisms of disease. RESULTS: A classification of HSV keratitis and uveitis is introduced based on the literature and the experience of the author in treating patients with this condition. CONCLUSIONS: There are multiple mechanisms of disease after ocular HSV infection, including damage from live virus, from immune and inflammatory mechanisms, and from structural damage in the aftermath of HSV infection (metaherpetic disease). Clinical, pathologic, and etiologic descriptions of these disease manifestations are offered. This may allow better communication between clinicians and authors of research protocols by defining the different aspects of this complex disease process.

Cornea↗
PubMedDate not supplied

[Defective proviruses of the human T-cell leukemia virus: structure and classification].

Peripheral blood mononuclear cells of 24-70% individuals infected with HTLV-1 contain defective proviruses (dp) in addition to the full size ones. Most of them remain silent lacking regions sufficient for viral genes transcription except those activated under cell promoter or retaining viral open reading frames (orfs). It is still unclear whether these proviruses are associated with the development of T-cell leukemia in adults, tropic spastic paresis, or myelopathy. Classification of previously reported dp is presented, their origin and possible function in human HTLV-1 associated diseases are discussed.

Defective Viruses↗
PubMed1994

Proposals for a new classification of iridescent viruses.

The need for comparative studies of iridoviruses to elucidate the relationships between them has been well appreciated. Sixteen iridoviruses, including type species from each of the four recognized genera of the Iridoviridae, were compared by restriction endonuclease characterization, hybridization to the major structural protein (MSP) gene of an invertebrate iridescent virus (IV) isolate at various stringencies, PCR amplification of the MSP gene region and by dot-blot hybridization studies. The results broadly supported previous serological studies. The vertebrate iridoviruses, frog virus 3 (genus Ranavirus) and flounder lymphocystivirus (genus Lymphocystivirus), appeared distinct from one another and from the invertebrate isolates. Naming and numbering invertebrate IV isolates according to history and host is no longer useful since IVs infect a number of species. A revised system, involving names based on the geographical origin of the isolate is proposed, in line with other virus families. The large IVs of invertebrates represented by Vero Beach IV (previously IV3 or mosquito IV; genus Chloriridovirus) showed little similarity to any other IVs. Members of the genus Iridovirus, the small invertebrate IVs, fell into three distinct groups of interrelated isolates. The largest group, containing the Plowden (IV1), Tia (IV2), Nelson (IV9, IV10 and IV18), Aberystwyth (IV22), Srinagar (IV24), Fort Collins (IV29) and Stoneville (IV30) iridoviruses, is named the Polyiridovirus complex. The Plowden iridovirus (IV1) is suggested as type species for this complex given the data available on its molecular biology. Based on previously published data, Timaru (IV16 and IV19) and Uitenhage (IV23) iridoviruses are also assigned to this complex. The second but smaller group is named the Oligoiridovirus complex, which includes Dazaifu (IV6) as the type species and contains Ntondwe (IV21 and IV28) on a tentative basis. Riverside IV (IV31) was distinct from both of the other groups, and is proposed as a third complex, Crustaceoiridovirus.

Animals↗
PubMed2003

Molecular evidence supporting the classification of Hosta virus X as a distinct species of the genus.

Apotexvirus, Hosta virus X (HVX-Kr), causing mosaic and mottle symptoms was isolated from hosta plants ( Hosta spp.) in Korea. The 3'-terminal 2,711 nucleotides excluding the poly (A) tail were determined and shown to include the partial viral replicase, triple gene block (TGB) 1 (26 kDa), TGB2 (13 kDa), TGB3 (8 kDa), and 23 kDa coat protein (CP) and the 3'-nontranslated region (NTR), typical of potexviruses. The CP gene of the type isolate of HVX (HVX-U) was amplified by RT-PCR and its nucleotide sequence was determined. The CPs of HVX-Kr and HVX-U had 100% and 98.9% identical amino acids and nucleotides, respectively. Most of the regions of the genome HVX had over 50% nucleotide identical to other sequenced potexviruses. This is the first report of sequence information of HVX and molecular evidence supporting the virus as a distinct species of the genus Potexvirus.

3' Untranslated Regions↗
PubMed1988

The use of filter hybridization techniques for the identification, differentiation and classification of plant viruses.

In attempts to use dot-blot hybridization tests for the identification of viruses or for assigning them to a certain taxonomic group we found that hybridization signals may be given not only by the homologous virus, but also by heterologous viruses belonging to the same or different taxonomic groups. Possible reasons for this phenomenon, which was observed with uncloned as well as with cloned cDNAs, are discussed. Quantitative dot-blot hybridization tests with extracted viral RNAs proved to be very sensitive in differentiating closely related viruses which were barely distinguishable in serological tests. Estimates on the degree of homology between the RNAs of different viruses may be influenced by a number of experimental parameters, such as competition for the available cDNA between homologous and heterologous RNAs or homologous RNAs in different concentrations on the same sheet of nitrocellulose, saturation phenomena due to close packaging of highly concentrated RNA on the blot and, of course, stringency conditions during washing procedures. Taking these parameters into account we have reestimated the degree of homology between the RNAs of 5 tombusviruses. Our new data suggest that the order of sequence for the relationships among these 5 tombusviruses is similar to that proposed by Koenig and Gibbs (1986) on the basis of serological data.

DNA↗