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This causes an immune response, resulting in common symptoms as phagocytes break down the bacteria within the host. Some bacteria, such as H. pylori, can secrete toxins into the surrounding tissues, resulting in cell death or inhibition of normal tissue function. Viruses, however, use a completely different mechanism to cause disease.
Antitermination was discovered in bacteriophage infections. A common feature in the control of phage infection is that very few of the phage genes can be transcribed by the bacterial host RNA polymerase. Among these genes, however, are regulators whose products allow the next set of phage genes to be expressed.
One process is a one-step mechanism in which proteins from the cytoplasm of bacteria are transported and delivered directly through the cell membrane into the host cell. Another involves a two-step activity in which the proteins are first transported out of the inner cell membrane, then deposited in the periplasm , and finally through the outer ...
P1 is a temperate bacteriophage that infects Escherichia coli and some other bacteria. When undergoing a lysogenic cycle the phage genome exists as a plasmid in the bacterium [1] unlike other phages (e.g. the lambda phage) that integrate into the host DNA.
Bacteria have various mechanisms for colonizing host tissues. For example, biofilm production allows bacteria to adhere to the host tissue surface, and it provides a protective environment ideal for bacterial growth. [4] Some bacteria, such as spirochetes, are capable of proliferating the host cell or tissues. This then allows the bacterium to ...
Some bacteria, such as Streptococcus pyogenes, Staphylococcus aureus and Pseudomonas aeruginosa, produce a variety of enzymes which cause damage to host tissues.Enzymes include hyaluronidase, which breaks down the connective tissue component hyaluronic acid; a range of proteases and lipases; DNases, which break down DNA, and hemolysins which break down a variety of host cells, including red ...
A transmission electron microscope image of isolated T3SS needle complexes from Salmonella Typhimurium. The type III secretion system (T3SS or TTSS) is one of the bacterial secretion systems used by bacteria to secrete their effector proteins into the host's cells to promote virulence and colonisation.
However, if the immune system or "good" microbiota are damaged in any way (such as by chemotherapy, human immunodeficiency virus (HIV), or antibiotics being taken to kill other pathogens), pathogenic bacteria that were being held at bay can proliferate and cause harm to the host. Such cases are called opportunistic infections.