Related Experiment Video
Updated: Jul 5, 2026
08:49
Transduction and Expansion of Primary T Cells in Nine Days with Maintenance of Central Memory Phenotype
Published on: March 18, 2020
Rapid evolution by positive Darwinian selection in T-cell antigen CD4 in primates
Zhengdong D Zhang1, George Weinstock, Mark Gerstein
1Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA.
Journal of Molecular Evolution
|April 17, 2008
Summary
The CD4 protein, crucial for immune response and HIV/SIV infection, evolves rapidly due to positive selection. This selection pressure, particularly on its surface where viruses bind, is linked to SIV infection in primates.
Area of Science:
- Evolutionary biology
- Immunology
- Virology
Background:
- CD4 is a key glycoprotein in immune response and HIV/SIV lifecycle.
- CD4 exhibits faster evolution than most mammalian genes, suggesting strong selective pressures beyond simple relaxation of purifying selection.
Purpose of the Study:
- Investigate the evolutionary dynamics of CD4.
- Identify regions and sites under positive selection.
- Explore the relationship between CD4 evolution, structure, and SIV interaction.
Main Methods:
- Comparative genomic analysis of orthologous human and mouse CD4 genes.
- Reconstruction of ancestral primate CD4 coding sequences.
- Tertiary structure modeling of ancestral and extant CD4 sequences.
- Structural mapping of positively selected sites.
Main Results:
- Identified significant positive selection acting on specific CD4 codon sites.
- Positively selected sites are located on the D1 domain surface, the binding site for SIV gp120.
- Ancestral CD4 sequences from SIV-infected primate lineages show greater variation in electrostatic charge and CD4-gp120 complementarity.
Conclusions:
- Positive selection on CD4 in primates is likely driven by SIV infection.
- Evolutionary changes in CD4 sequence and structure are linked to its interaction with immunodeficiency viruses.
More Related Videos
06:25Analysis of Simian Immunodeficiency Virus-specific CD8+ T-cells in Rhesus Macaques by Peptide-MHC-I Tetramer Staining
Published on: December 23, 2016
14:23A Restriction Enzyme Based Cloning Method to Assess the In vitro Replication Capacity of HIV-1 Subtype C Gag-MJ4 Chimeric Viruses
Published on: August 31, 2014
Related Concept Videos
01:22T Cell Activation and Clonal Selection
T cells are integral to our adaptive immune system, recognizing and effectively responding to foreign antigens. T cell activation and clonal selection are pivotal in orchestrating this immune response. This article elucidates these mechanisms, detailing the roles of cluster of differentiation (CD) markers, major histocompatibility complex (MHC) molecules, costimulatory signals, and the process of clonal selection.
Naive T cells that have not yet encountered an antigen express two primary CD...
Naive T cells that have not yet encountered an antigen express two primary CD...
01:16Transduction
Among the three main modes of HGT—transformation, conjugation, and transduction—transduction is unique in that it is mediated by bacteriophages, or bacterial viruses.Transduction occurs in two ways. Generalized transduction occurs during the lytic cycle of a bacteriophage infection. In this process, bacteriophages infect bacterial cells, replicate within them, and ultimately cause cell lysis, releasing newly assembled virions. Occasionally, random fragments of the bacterial genome are...
00:36Viral Mutations
A mutation is a change in the sequence of bases of DNA or RNA in a genome. Some mutations occur during replication of the genome due to errors made by the polymerase enzymes that replicate DNA or RNA. Unlike DNA polymerase, RNA polymerase is prone to errors because it is not capable of “proofreading” its work. Viruses with RNA-based genomes, like HIV, therefore accrue mutations faster than viruses with DNA-based genomes. Because mutation and recombination provide the raw material for adaptive...
01:24Evolution of New Traits in Microbes
Microorganisms evolve rapidly due to their large population sizes and short generation times, often exhibiting measurable changes within days under laboratory conditions. Natural selection acts on standing genetic variation, enabling the retention and amplification of beneficial traits that confer fitness advantages in changing environments.Adaptive Pigment Regulation in RhodobacterIn Rhodobacter, a genus of purple non-sulfur bacteria, light-harvesting pigments such as bacteriochlorophyll and...
01:23Cells of the Adaptive Immune Response
The T and B lymphocytes of the adaptive immune system develop from common lymphoid progenitor cells in the bone marrow. These progenitors give rise to precursors that eventually develop into both T and B lymphocytes. As these precursors mature, they gain the ability to detect and respond to foreign antigens in the body, a process known as immunocompetence. Additionally, these precursors acquire self-tolerance, a process that ensures they do not react to self-antigens. This intricate system...
01:28Diversity of Antigen Receptors
Antigen receptors are essential components of the immune system crucial in defending the body against foreign invaders. These receptors are present on the surface of B and T cells, enabling them to recognize antigens and mount an appropriate immune response.
Before encountering any antigen, lymphocytes express these receptors. On B cells, the antigen receptor is a membrane-bound antibody molecule called BCR; on T cells, it is a T cell receptor or TCR. B and T cell receptors are composed of two...
Before encountering any antigen, lymphocytes express these receptors. On B cells, the antigen receptor is a membrane-bound antibody molecule called BCR; on T cells, it is a T cell receptor or TCR. B and T cell receptors are composed of two...