Factors influencing the evolution of viral diseases at the cellular level and in the organism.
Explore the source record for details and available documents.
Biological Evolution↗
SEARCH · PubMed Health
Results for “virus evolution”
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Nonhomologous RNA recombination in tombusviruses: generation and evolution of defective interfering RNAs by stepwise deletions.
We used a protoplast system to study the mechanisms involved in the generation and evolution of defective interfering (DI) RNAs of tomato bushy stunt tombusvirus (TBSV). Synthetic transcripts corresponding to different naturally occurring TBSV DI RNAs, or to various artificially constructed TBSV defective RNAs, were analyzed. The relative levels of competitiveness of different DI RNAs were determined by coinoculating their corresponding transcripts into protoplasts along with helper genomic RNA transcripts and monitoring the level of DI RNA accumulation. Further studies were performed to assess the contribution of naked DI RNA stability and DI RNA encapsidation efficiency to the observed levels of competitiveness. In addition, the ability of various defective RNAs to evolve to alternative forms was tested by serially passaging protoplast infections initiated with transcripts corresponding to helper genomic RNA and a single type of defective RNA. These studies, and the analysis of the sequences of observed recombinants, indicate that (i) replication competence is a major factor dictating DI RNA competitiveness and is likely a primary determinant in DI RNA evolution, (ii) DI RNAs are capable of evolving to both smaller and larger forms, and the rates at which various transitions occur differ, (iii) DI RNA-DI RNA recombination and/or rearrangement is responsible for the formation of the evolved RNA molecules which were examined, and (iv) sequence complementarities between positive- and negative-sense strands in the regions of the junctions suggest that, in some cases, base pairing between an incomplete replicase-associated nascent strand and acceptor template may mediate selection of recombination sites. On the basis of our data, we propose a stepwise deletion model to describe the temporal order of events leading to the formation of tombusvirus DI RNAs.
Base Sequence↗
Unexpected absence of the Epstein-Barr virus (EBV) lyLMP-1 open reading frame in tumor virus isolates: lack of correlation between Met129 status and EBV strain identity.
The lytic cycle-associated lytic latent membrane protein-1 (lyLMP-1) of Epstein-Barr virus (EBV) is an amino-terminally truncated form of the oncogenic LMP-1. Although lyLMP-1 shares none of LMP-1's transforming and signal transducing activities, we recently reported that lyLMP-1 can negatively regulate LMP-1-stimulated NF-kappaB activation. The lyLMP-1 protein encoded by the B95-8 strain of EBV initiates from methionine 129 (Met129) of the LMP-1 open reading frame (ORF). The recent report that Met129 in the B95-8 LMP-1 ORF is not conserved in the Akata strain of EBV prompted us to screen a panel of EBV-positive cell lines for conservation of Met129 and lyLMP-1 expression. We found that 15 out of 16 tumor-associated virus isolates sequenced encoded an ATT or ACC codon in place of ATG in the LMP-1 ORF at position 129, and tumor cell lines harboring isolates lacking an ATG at codon 129 did not express the lyLMP-1 protein. In contrast, we found that EBV DNA from 22 out of 37 healthy seropositive donors retained the Met129 codon. Finally, the lyLMP-1 initiator occurs variably within distinct EBV strains and its presence cannot be predicted by EBV strain identity. Thus, Met129 is not peculiar to the B95-8 strain of EBV, but rather can be found in the background of several evolutionarily distinct EBV strains. Its absence from EBV isolates from tumors raises the possibility of selective pressure on Met129 in EBV-dependent tumors.
Base Sequence↗
Biological basis of the HLA-B8,DR3-associated progression of acquired immune deficiency syndrome.
The factors influencing the evolution of human immunodeficiency virus (HIV) infection are not fully known, but the host genotype undoubtedly plays a role in determining the outcome of the disease by affecting the immune response to HIV. The role of the host human leukocyte antigen (HLA) genotype in the regulation of susceptibility to HIV infection and expression has been studied extensively in different major risk groups. Certain HLA alleles and haplotypes, being associated with aberrant immune responses independently from HIV infection, have been reported to facilitate the rapid progression of disorders related to HIV infection. Particularly, the association of rapid acquired immunodeficiency syndrome (AIDS) progression with genes from the HLA-B8,DR3 haplotype has been reported by different research groups. It is well known that this haplotype is associated in all Caucasian populations with a wide variety of diseases with autoimmune features and in healthy subjects with a number of immune system dysfunctions, as a reduced production of T helper (Th)1 type cytokine. HIV infection may act on this genetic background triggering immunopathogenetic mechanisms leading to AIDS with a dominant Th2 profile as a common feature.
Acquired Immunodeficiency Syndrome↗
Evolution of a human cell line persistently infected with measles virus.
A measles-virus-carrier cell line, designated AV3/MV, was derived from established human amnion (AV3) cells surviving primary infection with the Edmonston strain of measles virus. During maintenance of infected cultures in the laboratory, the cells passed from a highly productive chronic phase (where infectious virus was continuously shed) to a less productive degenerative phase (where fewer infectious particles were produced). Carrier cultures in the less-productive phase gradually deteriorated and failed to survive at 37 degrees. However, when temporarily maintained and passaged at 39.5 degrees, the cultures stabilized and carried the virus in a latent or nonproductive state. Carrier cultures in the chronic phase of infection expressed variable degrees of virus-specific CPE, replicated erratically, and generated large amounts of virus-specific antigens. In the stabilized latent phase, the cultures demonstrated no virus-specific CPE, replicated steadily, and generated reduced amounts of virus-specific antigens. The results of our studies indicate that the establishment and maintenance of persistent measles virus infections in AV3 cells are dynamic processes involving numerous variables, and that there are similarities between these latent-carrier cell lines and certain virus-carrier cell lines derived from subacute sclerosing panencephalitis brain tissues.
Amnion↗
Genetic analysis of HIV by in situ PCR-directed laser capture microscopy of infected cells.
Behind the exponential expansion of the acquired immunodeficiency syndrome (AIDS) epidemic, there is a continuous and progressive molecular evolution of human immunodeficiency virus (HIV)-1. In this regard, the molecular analysis of viral strains infecting several anatomic compartments in humans has become critical to understanding AIDS-related pathologies and to improving emerging therapeutic protocols. Laser capture microdissection provides outstanding results in the genetic analysis of HIV-1 variants detectable in AIDS patients. The ability of the instrument to microdissect infected cells from a heterogeneous tissue compartment allows the investigator to obtain critical information regarding the genetic nature of a specific viral strain. To perform laser capture microdissection with better accuracy, a priori detection techniques may provide useful information about HIV distribution in the tissue specimen. An in situ polymerase chain reaction (PCR) assay on a serial slide results in a detailed map of the viral infection specific for the case under analysis. The knowledge of HIV distribution in the tissue section is critical for improving the dissection of infected cells by laser capture microscopy. This chapter describes laser capture microdissection and in situ PCR and its role in the analysis of the genetic nature of HIV-1 variants and quasispecies.
AIDS-Associated Nephropathy↗
Detection of nirsevimab-resistant RSV-B variants in children carrying the F:N201T substitution through genomic surveillance, Spain, 2025/26 season.
During Spain's 2025/26 RSV season, three children were infected with RSV-B viruses carrying the F protein N201T substitution. Two who received nirsevimab that season were hospitalised (one required intensive care); the third was treated previously. Recombinant expression studies confirmed reduced nirsevimab recognition. Genomic data indicated sporadic emergence across distinct RSV-B backgrounds rather than expansion of a single lineage. Findings highlight the importance of combining genomic surveillance with antigenic characterisation to detect and interpret variants with reduced susceptibility to antibody-based prevention.
Humans↗
Age-associated change in the frequency of memory CD4+ T cells impairs long term CD4+ T cell responses to influenza vaccine.
We investigated the relationship of memory CD4+ T cells with the evolution of influenza virus-specific CD4+ T cell responses in healthy young and elderly people. Elderly individuals had a similar frequency of CD69+CD4+ T cells producing IFN-gamma and TNF-alpha at 1 wk, but a lower frequency of these CD4+ T cells at 3 mo after influenza vaccination. Although the elderly had a higher frequency of central memory (CM; CCR7+CD45RA-) CD4+ T cells, they had a significantly lower frequency of effector memory (EM; CCR7-CD45RA-) CD4+ T cells, and the frequency of the latter memory CD4+ T cells positively correlated with the frequency of influenza virus-specific CD69+CD4+ T cells producing IFN-gamma at 3 mo. These findings indicate that the elderly have an altered balance of memory CD4+ T cells, which potentially affects long term CD4+ T cell responses to the influenza vaccine. Compared with the young, the elderly had decreased serum IL-7 levels that positively correlated with the frequency of EM cells, which suggests a relation between IL-7 and decreased EM cells. Thus, although the healthy elderly mount a level of CD4+ T cell responses after vaccination comparable to that observed in younger individuals, they fail to maintain or expand these responses. This failure probably stems from the alteration in the frequency of CM and EM CD4+ T cells in the elderly that is related to alteration in IL-7 levels. These findings raise an important clinical question about whether the vaccination strategy in the elderly should be modified to improve cellular immune responses.
Adult↗
[Nutritional status and clinical evolution of hospitalized Chilean infants with infection by respiratory syncytial virus (RSV)].
Respiratory syncycial virus (RSV) is the first cause of acute lower respiratory tract infection in Chilean infants. A significant impact of nutrition on clinical course of these infections has been described. In order to analyze the association between nutritional status (NS) and clinical course of infants hospitalized with acute lower respiratory tract infection due to RSV, 130 infants (mean age 5.8 +/- 4.9 m) without chronic diseases, admitted to hospital with confirmed RSV infection, were studied. Clinical course of disease was assessed (hospitalization days and days with oxygen therapy) according to nutritional status on admission (weight/length (W/L), ratio, arm muscle area, lymphocyte count and albumin), antropometrics changes, and hospital dietary intake. On admission prevalence of malnutrition by W/L (z score) was 1%, 14% overweight and 8% were obese. Median value of hospitalization days was 5 d (2-29 d) and days receiving oxygen was 3 d (0-19 d). Longer admission were observed in fasted patients than in those who were fed everyday (Wilcoxon and Log-rank test, 8 d vs 5 d; P < 0.01). Obese children (Wilcoxon and Log-rank test, 5 d vs. 3d in normal patients; P < 0.05), and patients not fed enterally (Wilcoxon and Log-rank test, 7 d vs. 3 d; P < 0.01) required oxygen for longer time. Fasting and severity of illness (Tal score) were correlated variables (X2 0.001). The multivariate analysis showed an association of Tal score and NS on admission, with days receiving oxygen therapy. We conclude that obesity is a risk factor for worse clinical course of acute lower respiratory tract infection in Chilean infants with RSV infection and without chronic disease.
Acute Disease↗
[Dynamics of intrathecal immunoglobulin synthesis].
INTRODUCTION: Dynamics of the immune response in Central Nervous System (CSN) is different from the well-known switch of IgM synthesis to IgG synthesis in blood. OBJECTIVE: Broadcast the behavior and the factors involved in the dynamics of the intrathecal immune response in infectious neurological disorders. DEVELOPMENT: The lack of a switch from IgM class response to IgG response could be more related to regulation-modulation mechanisms of the CNS immune response than differs from blood in a different cytokines composition, and the possibility of chemokines synthesis during the neuroinflammatory process, and the neuroimmune-endocrine mechanisms. The immune pattern can be stable like neuroborreliosis, and can be modify like in herpes simplex meningoencephalitis. It could have a typical pattern like in Neisseria meningitidis meningoencephalitis and neurotuberculosis. Also the pattern could be still detectable for many years after sufficient treatment and complete recovery of the symptom-free patients like in neurosyphilis or an advanced precocious response during the childhood. In HIV encephalopathy the pattern remains the same during the evolution but in other virus infections, like Echo 6 or Coxsackie B5, depends on the biological agent. CONCLUSIONS: In order to know the acuity of the disease, we have to know the physiopathologic characteristics of the biological agents, time courses, locations of the pathological processes, and the host age. The main signs in cerebrospinal fluid of an acute, active disease of CNS are the increased of cerebrospinal fluid cell count and the increased of albumin ratio.
AIDS Dementia Complex↗
Evolutionary aspects of Myxomatosis in Australia.
Explore the source record for details and available documents.
Australia↗
[Experimental investigations of murine hepatitis. IV. Evolution of hepatitis induced with MHV-2 and MHV-4 viruses in adult white mice exposed to the action of x-rays].
Explore the source record for details and available documents.
Animals↗
[Experimental investigations of murine hepatitis. I. Evolution of hepatitis induced with MHV-2 and MHV-4 viruses in mice exposed to the action of radiophosphorus (P-32) and radioiodine (I-131)].
Explore the source record for details and available documents.
Animals↗
[The evolution of experimental encephalitis in mice infected with the tick virus and exposed to irradiation with beta and gamma rays].
Explore the source record for details and available documents.
Animals↗
Virological and immunological response to antiretroviral therapy in HIV-1 infected children: genotypic and phenotypic assays in monitoring virological failure.
Children differ from adults in both natural history of HIV-1 infection and their response to anti-retroviral therapy (ART). ART appears to be less successful in children than in adults at reducing HIV-1 RNA to below the level of detection of current assays. Nonetheless, children receiving ART frequently experience rises in CD4 cell counts, even in the absence of full virological suppression in plasma (discordant response). This immune repopulation in the presence of viral replication may increase the risk of emergence of drug-resistant viral variants. While the rationale for resistance testing is to optimise therapy, particularly when drugs are being changed following virological failure, it should be pointed out that currently available genotypic and phenotypic assays fail to detect drug resistance in about one third of viremic ART-treated children. This cannot be fully explained by the limitation of assays in detecting minor variants; factors other than resistance might be involved in the failure of therapy. Reduced fitness of drug-resistant viral variants is also unlikely to fully explain the discordant response to therapy, since immunological recovery is often observed even in the absence of detectable drug resistance. Rather, restoration of thymic function and higher thymic output may play a critical role in sustaining peripheral CD4 cell increases despite the persistence of viral replication. Such immune recovery might also drive the evolution of the replicating viruses.
Anti-HIV Agents↗
What about the ducks? An alternative vaccination strategy.
Like most emerging disease threats, avian influenza is a zoonotic disease maintained in nature by wildlife. In this case, the reservoir of infection is migratory waterfowl, primarily ducks. Rather than trying to vaccinate most of the world's human population in response to the threat of an avian influenza pandemic, it might be more prudent to vaccinate key reservoir wildlife species from which pandemic strains evolve. This strategy would require a much more intensive research effort to understand the evolution of avian influenza viruses in nature, but it would be far less costly than any of the alternatives. Research priorities for emerging zoonoses, such as new strains of avian influenza viruses, should be re-evaluated with an emphasis on ways to intervene at their source, the natural reservoir hosts from which they originate, rather than focusing up on human-based interventions, which are too often too late.
Animals↗
[Comparative morphology of spontaneous hepatitis A in lower Old World monkeys].
Detailed description of liver damage in two species of macaques (rhesus and fascicularis) and green monkeys with spontaneous hepatitis A (HA) induced by the virus similar to human hepatitis. A virus (HAV) is given. Evolution of histological changes was followed by serial liver biopsies. The picture of the hepatitis in the above monkey species resemble that of human NA as well as HA in other monkey species susceptible to HAV. Only in 8 of 21 monkeys the disease lasted for 2-5 months, others exhibited undulating and lingering course which lasted 8-19 months from the beginning of the infection. The lingering course of the infection was caused by HAV persistence in the host with its periodical elimination in faeces.
Animals↗
[Evolution of laboratory technics in the detection of herpes simplex virus infections].
In this report we proved that all of three methods for laboratory diagnosis of HSV infections which we used, have approximately the same degree of sensibility. Even though there is no statistically significant differences among sensibility of chosen methods, we think that IF test by monoclonal antibodies is the most suitable method for the routine work, in consideration of the high sensibility, typical specificity and fast results.
Adolescent↗