MreB

Examples of MreB in the following topics:

• MreB and Determinants of Cell Morphology

  • Also, bacteria that are naturally spherical do not have the gene encoding MreB.
  • Prokaryotes carrying the mreB gene can also be helical in shape.
  • MreB has long been thought to form a helical filament underneath the cytoplasmic membrane.
  • Recent research shows that peptidoglycan precursors are inserted into cell wall following helical pattern which is dependent on MreB, and it's reported that MreB also promote the GT activity of PBPs.
  • Procaryotic MreB in cartoon representation.

• Peptidoglycan Synthesis and Cell Division

  • However, it is actually the MreB protein that facilitates cell shape.

• Tests That Differentiate Between T Cells and B cells

  • B-cells are also white blood cells and are a vital part of the humoral immunity branch of the adaptive immune system.
  • Alternatively, B-cells can be distinguished from other lymphocytes like T cells and natural killer cells (NK cells) by the presence of a protein on the B-cell's outer surface called a B-cell receptor (BCR).
  • B-lymphocytes express CD19 marker.
  • The expression of different markers allows the separation/differentiation of T and B cells.
  • These techniques are based on staining B and T cells for unique cell surface markers known as cluster of differentiation (CD).

• Making Memory B Cells

  • Memory B cells are a B cell sub-type that are formed following primary infection.
  • Memory B cells are a B cell sub-type that are formed following a primary infection .
  • Most of them differentiate into the plasma cells, also called effector B cells (which produce the antibodies) and clear away with the resolution of infection.
  • To understand the events taking place, it is important to appreciate that the antibody molecules present on a clone (a group of genetically identical cells) of B cells have a unique paratope (the sequence of amino acids that binds to the epitope on an antigen).
  • B lymphocytes are the cells of the immune system that make antibodies to invading pathogens like viruses.

• Cell-Mediated Autoimmune Reactions

  • A normal immune response is assumed to involve B and T cell responses to the same antigen, where B cells recognize conformations on the surface of a molecule for B cells, and T cells recognize pre-processed peptide fragments of proteins for T cells.
  • Roosnek and Lanzavecchia showed that B cells recognizing IgGFc could get help from any T cell that responds to an antigen co-endocytosed with IgG by the B cell as part of an immune complex.
  • Together with the concept of T cell-B cell discordance, this idea forms the basis of the hypothesis of self-perpetuating autoreactive B cells.
  • Autoreactive B cells in spontaneous autoimmunity are seen as surviving because of subversion both of the T cell help pathway and of the feedback signal through the B cell receptor.
  • In this process T-cells are stimulated to grow and can signal B-cells to produce antibodies.

• Group B Streptococcus Colonization

  • Group B streptococcus is part of the natural microflora in some people, but can sometimes cause life-threatening infections.
  • Group B streptococcus (GBS), also called streptococcus agalactiae or simply strep B, is part of the natural genital and intestinal microflora in some people.
  • If a pregnant woman is a carrier of strep B, the baby can become infected during vaginal delivery.
  • The reason for that is the interaction between the CAMP factor from strep B and the s. aureus hemolysin.
  • Describe the pathogenic characteristics, symptoms and diagnostic test used for Group B streptococcus (GBS)

• Brucellosis (Undulant Fever)

  • Species infecting domestic livestock are B. melitensis (goats and sheep), B. suis (pigs), B. abortus (cattle), B. ovis (sheep), and B. canis (dogs).
  • B. abortus also infects bison and elk in North America and B. suis is endemic in caribou.
  • Some vaccines used in livestock, most notably B. abortus strain 19, also cause disease in humans if accidentally injected.

• Adaptive Immunity and the Immunoglobulin Superfamily

  • Immunoglobulins are produced in a membrane-bound form by B lymphocytes.
  • These membrane molecules function as B cell receptors for antigens.
  • The interaction of antigens with membrane antibodies on naive B cells initiates B cell activation .
  • These activated B cells produce a soluble form of immunoglobulin that triggers effector mechanisms to eliminate antigens.
  • When a B cell encounters its triggering antigen, it gives rise to many large cells known as plasma cells.

• Isotype Class Switching

  • Isotype class switching is a biological mechanism that changes a B cell's production of antibody from one class to another.
  • The antibody isotype of a B cell changes during cell development and activation.
  • Immature B cells, which have never been exposed to an antigen, are known as naïve B cells and express only the IgM isotype in a cell surface bound form.
  • B cells begin to express both IgM and IgD when they reach maturity; the co-expression of both of these immunoglobulin isotypes renders the B cell 'mature' and ready to respond to an antigen.
  • Mechanism of class switch recombination that allows isotype switching in activated B cells.

• Defective Viruses

  • Therefore, it is a defective virus and cannot replicate without the help of hepatitis B virus.
  • Therefore, it is a defective virus and cannot replicate without the help of hepatitis B virus.
  • It is one of five known hepatitis viruses: A, B, C, D, and E.
  • Transmission of HDV can occur either via simultaneous infection with HBV (coinfection) or superimposed on chronic hepatitis B or hepatitis B carrier state (superinfection).
  • In combination with hepatitis B virus, hepatitis D has the highest mortality rate of all the hepatitis infections of 20%.