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At least 1,747 records · Page 97Linked to original sources
PubMed2006

Close relationship between SARS-coronavirus and group 2 coronavirus.

The sudden appearance and potential lethality of severe acute respiratory syndrome (SARS)-associated coronavirus (SARS-CoV) in humans has resulted in a focusing of new attention on the determination of both its origins and evolution. The relationship existing between SARS-CoV and other groups of coronaviruses was determined via analyses of phylogenetic trees and comparative genomic analyses of the coronavirus genes: polymerase (Orf1ab), spike (S), envelope (E), membrane (M) and nucleocapsid (N). Although the coronaviruses are traditionally classed into 3 groups, with SARS-CoV forming a 4th group, the phylogenetic position and origins of SARS-CoV remain a matter of some controversy. Thus, we conducted extensive phylogenetic analyses of the genes common to all coronavirus groups, using the Neighbor-joining, Maximum-likelihood, and Bayesian methods. Our data evidenced largely identical topology for all of the obtained phylogenetic trees, thus supporting the hypothesis that the relationship existing between SARS-CoV and group 2 coronavirus is a monophyletic one. Additional comparative genomic studies, including sequence similarity and protein secondary structure analyses, suggested that SARS-CoV may bear a closer relationship with group 2 than with the other coronavirus groups. Although our data strongly suggest that group 2 coronaviruses are most closely related with SARS-CoV, further and more detailed analyses may provide us with an increased amount of information regarding the origins and evolution of the coronaviruses, most notably SARS-CoV.

Coronavirus↗
PubMed2004

HIV evolution and escape.

Human immunodeficiency virus (HIV) exemplifies the principles of Darwinian evolution with a telescoped chronology. Because of its high mutation rate and remarkably high rates of replication, evolution can be appreciated over periods of days in contrast to the durations conceived of by Darwin. Certain selective pressures that drive the evolution of HIV include chemotherapy, anatomic compartmentalization and the immune response. Examples of these selective forces on HIV evolution are described.

AIDS Vaccines↗
PubMed1988

Evolution of cancer genes as a mutation-driven process.

Cancer is primarily a somatic genetic disease resulting from the accumulation of several precancerous mutations in a cell lineage. The evolution of highly oncogenic retroviruses has been used as a model for the evolution of a cancer cell. The properties of intermediates between one set of replication-competent retrovirus and protooncogene progenitors and the homologous highly oncogenic retrovirus were analyzed to differentiate between selection-driven and mutation-driven models of this evolution. In this case and in some other cases where sufficient data are available, it appears that the intermediates in the evolution of highly oncogenic retroviruses are not transforming, indicating that they were not formed in a purely selection-driven process. Furthermore, analysis of retrovirus mutation rates indicates that there is a high rate of mutation in retrovirus replication such that the evolution of highly oncogenic retroviruses could be mutation-driven. Other evidence is mentioned suggesting that oncogenesis in general is at least partially mutation-driven, although mutational mechanisms are involved that are different from those involved in the evolution of highly oncogenic retroviruses.

Biological Evolution↗
PubMed1981

Theoretical evidence for the significance of certain types of DNA secondary structure in the genomes of phi X174, G4, fd, SV40 and the plasmid pBR322.

The significance of certain types of DNA secondary structure was assessed on a purely theoretical basis by analyzing their distribution over the entire genomes of bacteriophages phi X174, G4, fd, the eucaryotic virus SV40 and the E. coli plasmid pBR322. A computer program was designed to search the translated and non-translated (intercistronic) regions of these genomes for the potential of forming perfect hairpins (perfectly base paired stems: no G-T pairing; no interruptions) with small loops. The number of found occurrences was then compared to the statistically expected number. The results reveal a significant excess in each genome of perfect hairpins with stem length greater than 7 and end loops less than or equal to 20 over that expected given their nucleotide composition. For stem length of 5 to 7 the same observation holds true for the intercistronic regions, but for translated regions the number of such structures is below expectation. This suggests an evolutionary selection for these structures.

Biological Evolution↗
PubMed1984

[The reaction of antibody-dependent cell-mediated cytotoxicity (ADCC)].

The antibody-dependent cell-mediated cytotoxicity (ADCC) is a cytotoxic reaction mediated by non immune cells (effector cells) against target cells sensitized by antibodies which are specific of the target cells' surface antigens. Those antibodies belong mostly to the IgG class. Several kinds of leucocytes can play a role in ADCC. All of them bear a receptor for the Fc fragment of the immunoglobulins. The efficacy of each population of effector cells varies according to the animal species and the type of the target cell. Some ADCC effectors are very similar to the natural killers (NK) but they do not belong exactly to the same subpopulation. ADCC can be studied by an indirect method (Cr51 release) or by a direct visual method (single cell assay). Several substances can influence ADCC reactions: corticoids either do not modify or inhibit the reaction. Interferon does not interact with ADCC nor enhances it. Antibiotics do not influence the reaction. Complement enhances the ADCC. Complement reduces the concentration of antibodies and the number of effector cells required for lysis. ADCC plays a role in several biological processes like graft rejection, autoimmune diseases, antitumoral defence, antiparasitical defence, antiviral defence which seems to be its most important role in domestic animals. ADCC can be used to study the evolution of sensitizing antibodies following a viral infection.

Adrenal Cortex Hormones↗
PubMedDate not supplied

Drug induced hepatitis.

During the last decade an increased incidence of the adverse reactions to drugs with liver involvement was found. The liver lesions produced by drugs constituted a constant concern. We followed the course of liver disease produced by tuberculostatics, cytostatics, antidepressive, antibiotics, narcotics, antirheumatics, by biochemical, immunological and morphological investigations (needle biopsy of the liver with optical and electronic microscopy). The pattern of the damage to the liver ranges from minimal functional changes to severe aspects with cytolysis and cholestasis. Hypersensitivity to drugs (cutaneous eruption, rash, fever, eosinophilia) were observed only in three cases. The cholestatic clinical form was the most frequently encountered, raising problems of differential diagnosis with acute viral hepatitis and obstructive jaundice. Clinical evolution of drug induced hepatic lesions is favourable as soon as the administration of drug is arrested. Chronic evolution, as reported in the literature when the administration of hepatotoxic drug is continued, was noted only in one patient who was using Chlorpromazine.

Biopsy, Needle↗
PubMed1993

[Milestones in virology].

The "milestones" of virology try to depict the development from variolation to construction of hybrid viruses. Not only single observations or detections are listed, in contrast, this is an attempt to delineate from single events conclusions for the more general development of virology. Because of the increase of specialization in experimental sciences, it is often difficult for researchers to realize the roots of their present problems. Often, earlier conclusions are being overlooked, from which recent experimentations have been delineated.

Animals↗
PubMedDate not supplied

[The importance of the Epstein-Barr virus and other viruses in the evolution of human host homeostatic systems].

There is a great number (150) DNA sequence homology with genes and mRNA of man. They are involved in expression of biological active matters, which are participate in homeostasis of host. This is an evidence of a long-time co-evolution EBV and host-man populations. It play a great role in a vertical and horizontal dissemination some important for homeostasis genes of man.

Biological Evolution↗
PubMed1995

[Prospective study of the incidence of post-transfusion hepatitis after the exclusion of donors positive for anti-HCV ELISA 2].

BACKGROUND: The incidence of post transfusional hepatitis (PTH) after the exclusion of anti-HCV ELISA 2 positive donors is not well known. The aim of this study was to determine the incidence and type of PTH in 113 post transfused patients. METHODS: A post transfusional follow up was performed for at least one year with periodic controls of transaminase levels. When an increase in GPT level compatible with PTH was demonstrated investigation of all the virus related with the transfusion was carried out in both the donor and the transfused subject: HAV, HCV, HEV, HBV and CMV. RESULTS: Four cases (3.5%) were detected which fulfilled the PTH criteria with the following characteristics: short period of time between transfusion and the increase in GPT level, moderate GPT increase, moderate clinical expression and good evolution. In all the cases the viral study was negative and other non viral possibilities were eliminated. CONCLUSIONS: Transfusions are currently relatively safe and the increase in transaminases may not be related with transfusion.

Adolescent↗
PubMed1997

[Molecular evolution of paramyxoviruses].

We reviewed immunological relationships between paramyxoviruses and molecular evolution of paramyxoviruses. (1) paramyxoviruses are divided into two groups by the basis of the immunological relationship, i.e., parainfluenza type 1 virus group and type 2 virus group; (2) according to the NP and M proteins sequences, paramyxoviruses are divided into parainfluenza type 1 virus and type 2 virus groups; the former group is composed of HPIV-1, SV, HPIV-3 and BPIV-3, and the latter group consists of HPIV-2, SV41, SV5, MuV, HPIV-4A and HPIV-4B; and this grouping coincides with that by immunological relationships; (3) alignment of the P and V proteins of paramyxoviruses demonstrates that irregular gaps are present around the RNA-editing sites, suggesting that dynamic processes have been occurred during molecular evolution; (4) the NP proteins of the morbilliviruses are more related to the parainfluenza type 2 group, while the M proteins show closer-relationship with the parainfluenza type 1 group; (5) the parainfluenza type 2 group can be subdivided into two groups, i.e., mammal and avian types; (6) phylogentic trees for mononegaviruses are constructed.

Evolution, Molecular↗
PubMed1997

Dynamic genome organization and gene evolution by positive selection in geminivirus (Geminiviridae).

Geminiviruses (Geminiviridae) are a diverse group of plant viruses differing from other known plant viruses in possessing circular, single-stranded DNA. Current classification divides the family into three subgroups, defined in part by genome organization, insect vector, and plant host range. Previous phylogenetic assessments of geminiviruses have used DNA and/or amino acid sequences from the replication-associated and coat protein genes and have relied predominantly on distance analyses. We used amino acid and DNA sequence data from the replication-associated and coat protein genes from 22 geminivirus types in distance and parsimony analyses. Although the results of our analyses largely agree with those reported previously, we could not always predict viral relationships based on genome organization, plant host, or insect vector. Loss of correlation of these traits with phylogeny is likely due to improved sampling of geminivirus types. Unrooted parsimony trees suggest multiple independent origins for the monopartite genome. genome organization is therefore a dynamic character. Estimates of nonsynonymous and synonymous nucleotide substitutions for extant and inferred ancestral sequences were used to evaluate hypotheses that the replication-associated and coat protein sequences evolve to accommodate plant host and insect vector specificities, respectively. Results suggest that plant host specificity does not solely direct replication-associated protein-evolution but that coat protein sequence does evolve in response to insect vector specificity. Genome organization and, possibly, plant host specificity are not reliable taxonomic characters.

Animals↗
PubMed1994

Evolution of feline leukemia virus variant genomes with insertions, deletions, and defective envelope genes in infected cats with tumors.

In order to study retroviral variation, selection, and viral correlates of in vivo pathogenicity, we documented the evolution of feline leukemia virus (FeLV) variants in cats that died with thymic lymphoma after infection with molecularly cloned subgroup A FeLV. Using genomic DNA from cat necropsy samples, we employed PCR to amplify and clone the envelope gene, which is a major determinant of the specific pathogenicity of different FeLV variants. In the envelope gene, mutations encoded scattered amino acid changes that did not cluster into clearly definable variable regions; however, characterization of these terminal variant sequences revealed a predominance of G-to-A and A-to-G nucleotide substitutions. Additionally, some cats harbored variants with recombinant subgroup B-like envelope genes, while the major variant from one cat had a 12-bp insertion in a region previously characterized as an immunodeficiency-inducing determinant. Finally, proviruses from tumor DNA frequently possessed envelope genes predicted to encode a protein truncated in the N-terminal half because of either premature termination codons or deletions ranging from 29 to 1,666 bp. In contrast, all envelope genes cloned from the bone marrow of one cat were predicted to encode full-length envelope product, and only a minority of proviral clones from a cat that did not develop a tumor had defective envelope genes. Thus, in the cat, viruses evolved from subgroup A FeLV that had point mutations, insertions, deletions, or recombinant envelope genes. Furthermore, defective variants were particularly prominent in T-cell tumors.

Amino Acid Sequence↗
PubMed1976

Endogenous C-type viruses: double agents in natural life processes.

C-type RNA viruses have been described in about 20 different vertebrate species. Their presence in man is suggested by electron microscopic, biochemical and serologic studies, although a definite re;icating human virus has not yet been isolated. These viruses are inherited through the germ cell and their production is regulated by genetic information carried in the host cell (i.e. endogenous virus). Two classes of endogenous C-type viruses have been recognized in certain animals particularly the mouse: ecotropic and xenotropic. They may have their counterparts in man. Ecotropic viruses spread through the host and can be easily transmitted to cells of the same species; they can produce malignancy. Xenotropic viruses cannot infect cells from their host species but are infectious for cells from heterologous species. The interaction between xenotropic and ecotropic viruses could lead to the transfer among species of genetic information relating to normal life processes and malignancy. These C-type viruses may play a role in evolution, normal development and differentiation as well as autoimmune disease and cancer.

Animals↗
PubMed1997

In vivo evolution of HIV-1 co-receptor usage and sensitivity to chemokine-mediated suppression.

Following the identification of the C-C chemokines RANTES, MIP-1alpha and MIP-1beta as major human immunodeficiency virus (HIV)-suppressive factors produced by CD8+ T cells, several chemokine receptors were found to serve as membrane co-receptors for primate immunodeficiency lentiretroviruses. The two most widely used co-receptors thus far recognized, CCR5 and CXCR4, are expressed by both activated T lymphocytes and mononuclear phagocytes. CCR5, a specific RANTES, MIP-1alpha and MIP-1 receptor, is used preferentially by non-MT2-tropic HIV-1 and HIV-2 strains and by simian immunodeficiency virus (SIV), whereas CXCR4, a receptor for the C-X-C chemokine SDF-1, is used by MT2-tropic HIV-1 and HIV-2, but not by SIV. Other receptors with a more restricted cellular distribution, such as CCR2b, CCR3 and STRL33, can also function as co-receptors for selected viral isolates. The third variable region (V3) of the gp120 envelope glycoprotein of HIV-1 has been fingered as a critical determinant of the co-receptor choice. Here, we document a consistent pattern of evolution of viral co-receptor usage and sensitivity to chemokine-mediated suppression in a longitudinal follow-up of children with progressive HIV-1 infection. Viral isolates obtained during the asymptomatic stages generally used only CCR5 as a co-receptor and were inhibited by RANTES, MIP-1alpha and MIP-1beta, but not by SDF-1. By contrast, the majority of the isolates derived after the progression of the disease were resistant to C-C chemokines, having acquired the ability to use CXCR4 and, in some cases, CCR3, while gradually losing CCR5 usage. Surprisingly, most of these isolates were also insensitive to SDF-1, even when used in combination with RANTES. An early acquisition of CXCR4 usage predicted a poor prognosis. In children who progressed to AIDS without a shift to CXCR4 usage, all the sequential isolates were CCR5-dependent but showed a reduced sensitivity to C-C chemokines. Discrete changes in the V3 domain of gp120 were associated with the loss of sensitivity to C-C chemokines and the shift in co-receptor usage. These results suggest an adaptive evolution of HIV-1 in vivo, leading to escape from the control of the antiviral C-C chemokines.

Adolescent↗
PubMed2025

Molecular Evolution and Zoonotic Potential of Muju Virus (Orthohantavirus puumalaense) in Craseomys regulus, Republic of Korea.

Orthohantavirus puumalaense causes hemorrhagic fever with renal syndrome in Europe, with Puumala virus (PUUV) as its primary representative. Muju virus (MUJV), harbored by Craseomys regulus, an Arvicolinae rodent species endemic to the Republic of Korea (ROK), is also a genotype of O. puumalaense. However, their genomic diversity and zoonotic potential remain largely unknown. To investigate their prevalence, 185 voles were collected from 23 regions of the ROK between 2012 and 2023. Serological assays detected anti-PUUV immunoglobulin G antibodies in five samples (3.1%), whereas reverse-transcription polymerase chain reaction confirmed MUJV RNA in identical specimens (2.7%). Amplicon-based nanopore sequencing facilitates near-complete genome recovery, enabling high-resolution comparative analysis. Phylogenetic analysis revealed distinct genetic lineages in Gangwon and Jeollabuk Provinces. Evolutionary rate estimates indicated greater sequence divergence in the S and L segments than in the M segment. A zoonotic risk assessment revealed that most MUJV variants exhibited moderate-to-high spillover potential. The molecular detection of MUJV in Cheorwon, Gangwon Province, expands its known geographic range and provides the first molecular evidence of MUJV circulation in this region. These findings highlight the need for continued surveillance and seroprevalence studies of MUJV to assess its potential for human exposure and public health relevance in the ROK.

Animals↗