Technology

Bacteria Antigens

Introduction

Bacteria are unicellular prokaryotic bacteria that divide via binary fission. They lack a nuclear membrane, and the nucleus is made up of a single circular double-stranded DNA helix. Plasmids are among the non-essential genomic structures. Permeases, cell wall production enzymes, sensor proteins, secretion system proteins, and, in aerobic bacteria, respiratory chain enzymes are all found in the cytoplasmic membrane. Bacteria range in size from 0.5 to 5 µm on average. They can, however, be as little as 0.3 µm and as large as 0.7mm.. They are classified into three types: cocci, straight rods, and curved or spiral rods.Fig.1 shows the basic structure.

Pilin and Pili

Many bacteria have protein-based, shorter “hair-like” structures (pili) that protrude from the cytoplasmic membrane. Pilin is a type of fibrous protein found in pilus structures in bacteria. These structures can be utilized for genetic material exchange or as a cell adhesion mechanism. Although not all bacteria contain pili or fimbriae, bacterial pathogens frequently connect to host cells via their fimbriae. Individual pilin molecules in Gram-negative bacteria, where pili are more numerous, are linked by noncovalent protein-protein interactions, whereas Gram-positive bacteria frequently have polymerized LPXTG pilin.

Capsule

A thin jelly-like material encases many bacterial cells termed a capsule, which protects them from phagocytosis. Capsules are often composed of polysaccharides, polypeptides, and hyaluronic acid. Light microscopy can be used to visualize bacterial capsules using specific staining procedures. A microcapsule is a layer that is too thin to be seen using light microscopy. It is referred to as the slime layer if it is so abundant that numerous cells are immersed in a shared matrix.

The cell wall

The cell wall is a tough and rigid peptidoglycan structure with specialized auxiliary components that surrounds the bacterium like a shell and resides outside the cytoplasmic membrane. It has a thickness of 10-25 nm. It has a thicker murein layer that contains teichoic acids and wall-associated proteins that aid in the pathogenic process in Gram-positive infections. Gram-negative bacteria’s cell wall has a permeable outer membrane into which the lipopolysaccharide responsible for Gram-negative infection pathogenesis is integrated. Gram-positive bacteria do not have such an exterior membrane on their cell walls.

Nucleus

The bacterial genome consists of a single circular double-stranded chromosome. Cytoplasmic membranes, mesosomes, ribosomes, and cytoplasmic inclusions are examples of other structures. Unlike eukaryotes, cytoplasm lacks a ribosome, Golgi apparatus, and cytoskeleton.

The pathogenesis of bacterial infection is a complex procedure, including the production of factors that promote adhesion, persistence, invasion, and toxigenicity. Genes encoding virulence factors can be found on mobile genetic elements like plasmids or bacteriophages or vast pathogenicity islands on bacterial chromosomes. Some bacteria enter tissues via epithelial cell junctions. Other bacteria infiltrate particular types of epithelial cells of the host and may enter the tissue. Some bacteria multiply within host cells, while others do not. Bacteria may remain confined in a vacuole composed of the host cell membrane when within the host cell. The vacuole membrane may be dissolved, and bacteria may be distributed in the cytoplasm.

An antigen is anything that stimulates an immunological reaction in another organism. This immune response might be as simple as an increase in inflammatory markers or as complex as activation of the adaptive immune system and antibody production. Antibodies include two or more distinct paratopes or antigen recognition sites, allowing them to recognize and battle the invading antigen. The number of antigen recognition sites varies according to antibody class. Any protein of interest detected by a bioassay or detection platform can also be referred to as an “antigen”.

Bacterial antigens have immunostimulatory activity, produced by a live intrasynovial bacteria or transported into the articular cavity by monocytes. Surface proteins, lipopolysaccharides, and peptidoglycans on the bacterial cell wall are bacterial antigens; these features assist germs in infecting other species by getting access between epithelial cells. Surface structures help bacteria infect other organisms and serve as a distinctive tag that antibodies and bacteriophages can recognize. Bacteriophages are bacteria-attacking viruses. Scientists are using antibodies and phages to create new detection and biosensing platforms to detect bacterial antigens in the environment and clinical samples quickly.

Bacterial toxins as antigens are among the most potent toxins in nature and can be extracellular (exotoxins) or a component of the bacterial cell membrane (endotoxin). Many gram-positive and gram-negative bacteria create exotoxins with significant medicinal implications. Many exotoxins are made up of A and B subunits. The B subunit generally facilitates toxin complex adhesion to a host cell and aids exotoxin entry into the host cell. The A subunit provides the hazardous action. Gram-negative bacteria’s LPS are bacterial cell wall components frequently released when the bacteria lyse. LPS in the bloodstream binds to circulating proteins, which subsequently engage with receptors on macrophages, neutrophils, and other reticuloendothelial system cells.

Bioclone offers thousands of purified recombinant bacterial antigens for various applications.

Learn More

Brochure (pdf)

Recombinant Bacterial Proteins and cDNA →

General Reference

Noorbakhsh S, Talebi-Taher M, Tabatabaei A. Identification of bacterial antigens and super antigens in synovial fluid of patients with arthritis: a cross sectional study. Med J Islam Repub Iran. 2013;27(1):12-16.

Fukazawa, Y et al. “Antibody Response to Bacterial Antigens: Characteristics of Antibody Response to Somatic Antigens of Salmonella typhimurium.” Infection and immunity vol. 1,3 (1970): 219-25. doi:10.1128/iai.1.3.219-225.1970

Fukazawa, Y., Shinoda, T., Yomoda, T., & Tsuchiya, T. (1970). Antibody Response to Bacterial Antigens: Characteristics of Antibody Response to Somatic Antigens of Salmonella typhimurium. Infection and immunity, 1(3), 219–225.

Hu, Yun-Fei et al. “Identification of Bacterial Surface Antigens by Screening Peptide Phage Libraries Using Whole Bacteria Cell-Purified Antisera.” Frontiers in microbiology vol. 8 82. 26 Jan. 2017

MORGAN, W., PARTRIDGE, S. Bacterial Antigens. Nature 143, 1025–1026 (1939)

Bioclone