Microbe virulence

Microbial virulence is often the outcome of the complex interactions that take place as the pathogen establishes itself in the human host. The molecular determinants of pathogenicity include factors that cause damage to the host cell and those that help the microbe establish productive infection for survival [35]. The human host immune response counters the presence of these microbes with its acquired or innate immune response arsenal with outcomes that range from acute to chronic or latent infections. A clear definition of the host and microbial... 

Hacker J, Kaper JB. Pathogenicity islands and the evolution of microbes. Annu Rev Microbiol 2000 54 641-679. Wren BW. Microbial genome analysis insights into virulence, host adaptation and evolution. Nature Rev Genet 2000 l[l] 30-39. 

Toxicity The quality of being poisonous, especially the degree of virulence of a toxic microbe or of a poison. [EU]... 

Although host defense peptide resistance has remained rare within microbes, concerns have been raised regarding the potential for clinical applications of peptides to provoke peptide-resistant phenotypes. Indeed, the introduction of antibiotics as novel microbial eradicators was met almost instantaneously with bacteria that had manifested various forms of resistance. Thus, precautions should be taken with potential therapeutic application of host defense peptides to minimize similar resistance as seen with antibiotics. Many bacterial species rely on the use of two-component sensory systems to invoke phenotypes that increase virulence and recently one such system, the Salmonella PhoPQ system, has been demonstrated to respond directly to host defense peptides. ... 

Hostettmann K, Marston A (1995) Saponins. Cambridge University Press, Cambridge Pareja-Jaime Y (2008) Tomatinase from Fusarium oxysporum f sp lycopersici is required for full virulence on tomato plants. Mol Plant Microbe Interact 21 728... 

Mihaljevic, R. R., Sikic, M., Klancnik, A., Brumini, G., Mozina, S. S., and Abram, M. (2007). Environmental stress factors affecting survival and virulence of Campylobacter jejuni. Microb. Pathog. 43,120-125. 

Bhunia, A. K., Steele, P., Westbrook, D., Bly, L., Maloney, T., and Johnson, M. (1994). A six-hour in vitro virulence assay for Listeria monocytogenes using myeloma and hybridoma cells from murine and human sources. Microb. Pathog. 16, 99-110. 

Enkerli, J., Bhatt, G., and Covert, S.F., Maackiain detoxification contributes to the virulence of Nectria haematococca MP VI on chickpea, Mol. Plant-Microbe Interact., 11, 317, 1998. 

Wasmann, C.C. and Van Etten, H.D., Transformation-mediated chromosome loss and disruption of a gene for pisatin demethylase decrease the virulence of Nectria haematococca on pea, Mol Plant-Microbe Interact., 9, 793, 1996. 

M Herrmann, A Haese, R Zocher. Effect of disruption of the enniatin synthetase gene on the virulence of Fusarium avenaceum. Mol Plant-Microbe Interact 9 226-232, 1996. 

Salmonella in the gut lumen can induce a host inflammatory response mediated by several proteins excreted from the bacterial cytoplasm through Salmonella TTSS-1. These virulence factors may play a role in the influx of neutrophils into the intestine and the resulting inflammation that leads to diarrhea and other symptoms (Norris et al., 1998) (Fig. 5.1). Inflammation is an important component of innate immunity that plays a role in recruiting host immune cells to damaged tissue or invading microbes. Interaction with components of the innate immune system initiates a cascade of events that can lead to elimination of the microbe (Singh et al., 2009). 

Many new microbial compounds with potential blocherbicldal activity have been Isolated, chemically characterized, and a portion of their biological activities determined using various bioassay techniques or by direct plant screening. Some of these compounds are virulence factors of plant pathogens, thus Information on these phytotoxins can benefit the development of microbes as herbicides and potentially provide new chemical herbicides. Data on some of these compounds and their structures are presented. Information on source, biological activity, and possible mode of action (when available) Is briefly summarized. 

Zabela, M.D., Fernandez-Delmond, I., Niittyla, T., Sanchez, P. and Grant, M., 2002, Differential expression of genes encoding Arabidopsis phospholipases after challenge with virulent or avirulent Pseudomonas isolates. Mol. Plant-Microbe Interactions 15 808-816. 

Common pathogenic bacteria may be responsible (Staphylococcus aureus, Streptococcus pneumoniae) but often organisms of lower natural virulence (Enterobacteriaceae, viruses, fungi) are causal and strenuous efforts should be made to identify the microbe including, if feasible, bronchial washings or lung biopsy. 

Elimination of these infectious diseases has been hindered for several reasons [1] 1) new human pathogens are being discovered and transmitted worldwide 2) known microbes are mutating to form new, more virulent forms 3) microbes are able to develop resistance to antibiotics 4) new, stronger pharmaceutical agents have the side effect of decreasing the host s resistance 5) the life of an individual suffering from a chronic disease can... 

---