Harmful Bacteria and Viruses (Class XII)

A culture of chicken cholera bacillus accidentally left on bench during warm summer months lost much of its ability to cause disease, but could protect birds from the effects of fresh virulent bacillus. Pasteur also obtained similar results for anthrax and rabies.

This enzyme splits starch and is of importance for digestion, but not for protection.

Baculovirus vectors in moth cell lines produce large amounts of glycosylated recombinant protein. The baculovirus is a natural infectious agent of insect cells.

T-cells are important for immunity to M. tuberculosis through the provision of Th1 cytokines.

Listeria monocytogenes is able to escape from phagocytic vacuoles and survive in the cytoplasm of phagocytic cells.

LMP-2A is a transmembrane protein that acts to block tyrosine kinase signaling. It inhibits activation of the viral lytic cycle.

Papillomaviruses have a genome size about 8 kilobases. They cause warts which are frequently benign but can convert to malignant carcinomas. This often occurs in people suffering from with epidermodysplasia verruciformis.

There is no evidence that vegetarian diet leads to excess Staphylococcus infections or to poor nutrition.

This is a major portal of entry, though not the only one. The chemokine receptors CXCR4 and CCR5 are also major portals of entry and reduce the CD4 positive helper T-cell numbers dramatically.

Staining with crystal violet is the means by which bacteria have been classified historically. This primitive but quick (and messy when done by hand!) classification has been of practical use however, and so has survived.

Superantigens simultaneously activate large numbers of T-cells carrying a particular T-cell receptor Vβ gene, by binding at a site distinct from the antigen-binding groove. Since there are 50 different Vβ genes in humans, a superantigen will react with approximately 1 : 50 T-cells in contrast to a conventional peptide antigen that will react with 1 : 104 to 1 : 108 T-cells. They do not react with the BCR.

Production of IL-4 by Th2 cells is not a part of granuloma formation, which involves Th1 activation rather than Th2 activation.

CMV is an example of herpesviruses. These are all large DNA viruses of which CMV is the largest; which is also known as human herpesvirus-5 (HHV-5).

The anti T-cell immunosuppression used to prevent graft rejection increases the risk of fungal and viral infections. Primary cytomegalovirus infection in a renal transplant recipient; bacterial pneumonia is a particular risk when the patient is neutropenic after bone marrow transplantation.

These are delayed type hypersensitivity skin tests which are mediated by T-cells.

Clinical evaluation of infection incidence in the field post-completion of an immunization programme of susceptible individuals provides the most important evidence of efficacy. Such data may take 2 or 3 years to be collected, depending on the periodicity of infection with the organism. Long term immunity data is collected over 25 years to check that the provoked immunity is life-long (especially in these days of longer life spans).

VZV lies dormant in sensory nerve ganglia (near the base of the nerves) for decades and re-emerges to cause shingles.

CXCR4 is a chemokine receptor which HIV utilizes as a coreceptor for entry into naive CD4+ T-cells and mature dendritic cells. Another chemokine receptor, CCR5, is used particularly for entry of HIV into immature dendritic cells, macrophages and activated effector or memory CD4+ T-cells.

Antibody may block the binding to target cell and would increase the rate of removal of toxin from the circulation by immune complex formation.