Antibacterial immune systems

Finally, the current work provides bacteria-sensitive lethal mutations that point out pest control possibilities. Since bsl mutants die when injected with bacteria, they focus our attention directly on the immune steps at which the insect is particularly vulnerable. In future work we need to identify the cellular and molecular processes that are blocked by these mutations. If we could learn to artificially interfere with an immune step that is blocked by a bsl, then an effective insecticide might be developed. Because of the demonstrated similarities in the antibacterial immune systems of Drosophila melanoqaster and fruit fly pests, it is hoped that such methods would lead to crop protection. 

PCP is commonly used as a wood preservative having both antifungal and insecticide properties. It has also been used in a range of areas for antifungal, antibacterial, general herbicide, and slime prevention in both industrial and consumer applications. Chronic exposure to PCP has effects on the liver, kidneys, and immune system. PCP also has the potential to cause reproductive problems and has been listed as a probable carcinogen. 

Linezohd (Zyvox) is an oxazolidinone, a tive-membered heterocychc ring that forms the core of the hnezohd structure. The approval of hnezohd by the FDA in 2000 marked the first new structural class of antibacterial introduced into medical practice in the United States in 40 years. It is notable for its activity against methicillin-resistant Staph aureus, MRSA, and vancomycin-resistant Enterococcus faecium, VRE. It is bacteriostatic rather than bactericidal but finds significant use in patients with an intact immune system. Like several other classes of antibacterials, linezolid is an inhibitor of protein synthesis. It interacts specifically with the RNA component of a bacterial ribosome subunit to prevent initiation of protein synthesis. 

This communication reports studies on the humoral antibacterial response in Drosophila and Ceratitis capitata, the Mediterranean fruit fly. The goal of our work is to understand the molecular mechanisms that protect flies from bacterial infection. Here we examine three questions 1) What genes encode antibacterial proteins 2) Does the antibacterial response involve the accumulation of new messenger RNAs And 3), what genes are necessary to survive a bacterial attack Answers to these questions will help us to determine the potential of blocking the immune system to control populations of insect pests. 

The immune system of Drosophila seems to have two main subsystems, one involving the antibacterial proteins and the other identified by bacteria-sensitive lethal mutations. The humoral subsystem results in the production of diffusible antibacterial proteins of at least three species. Stock Cu, which lacks the ABs found in wild type Drosophila and which is correspondingly more sensitive to infection, blocks a part of this subsystem. That the ABs do help flies to survive bacterial infections was shown by inducing ABs to appear in bsl mutants by injection of dead bacteria and then finding that the inoculated mutants would survive an otherwise lethal injection of live bacteria. Evidently inoculation induces processes (perhaps secretion of ABs) that can overcome the deficiency in the bsl mutations. Similar experiments showed that inoculation protects locusts from a lethal dose of bacteria (19). 

Tobacco smoke has been demonstrated to have multiple effects on the immune system. Some effects are seen in the lung, such as an increased number, but decreased functional ability (e.g. antibacterial phagocytosis), of alveolar macrophages. Other effects include impaired secretion of proinflammatoiy cytokines and decreased activity of NK cells. These and other mechanisms contribute to an immunosuppressive effect of smoking and an increased susceptibility to infections (Sopori, 2002). 

Antibacterial drugs can be either bactericidal or bacteriostatic The effectiveness of bacteriostatic drugs depends on an intact host immune system. Antimicrobial agents may be administered singly or in combination. Some combinations induce synergy and/or delay emergence of resistance. 

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