抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

http://www.klinikaikozpont.u-szeged.hu/pedia/images/pdf/CME_TEL/Full-Text/25.pdf

The Hallmarks of Aging

Antibiotics have always been considered one of the wonder discoveries of the 20th century. This is true, but the real wonder is the rise of antibiotic resistance in hospitals, communities, and the environment concomitant with their use. The extraordinary genetic capacities of microbes have benefitted from man's overuse of antibiotics to exploit every source of resistance genes and every means of horizontal gene transmission to develop multiple mechanisms of resistance for each and every antibiotic introduced into practice clinically, agriculturally, or otherwise. This review presents the salient aspects of antibiotic resistance development over the past half-century, with the oft-restated conclusion that it is time to act. To achieve complete restitution of therapeutic applications of antibiotics, there is a need for more information on the role of environmental microbiomes in the rise of antibiotic resistance. In particular, creative approaches to the discovery of novel antibiotics and their expedited and controlled introduction to therapy are obligatory.

Origins and Evolution of Antibiotic Resistance

Evolution of Protein Molecules

Tetracyclines were discovered in the 1940s and exhibited activity against a wide range of microorganisms including gram-positive and gram-negative bacteria, chlamydiae, mycoplasmas, rickettsiae, and protozoan parasites. They are inexpensive antibiotics, which have been used extensively in the prophlylaxis and therapy of human and animal infections and also at subtherapeutic levels in animal feed as growth promoters. The first tetracycline-resistant bacterium, Shigella dysenteriae, was isolated in 1953. Tetracycline resistance now occurs in an increasing number of pathogenic, opportunistic, and commensal bacteria. The presence of tetracycline-resistant pathogens limits the use of these agents in treatment of disease. Tetracycline resistance is often due to the acquisition of new genes, which code for energy-dependent efflux of tetracyclines or for a protein that protects bacterial ribosomes from the action of tetracyclines. Many of these genes are associated with mobile plasmids or transposons and can be distinguished from each other using molecular methods including DNA-DNA hybridization with oligonucleotide probes and DNA sequencing. A limited number of bacteria acquire resistance by mutations, which alter the permeability of the outer membrane porins and/or lipopolysaccharides in the outer membrane, change the regulation of innate efflux systems, or alter the 16S rRNA. New tetracycline derivatives are being examined, although their role in treatment is not clear. Changing the use of tetracyclines in human and animal health as well as in food production is needed if we are to continue to use this class of broad-spectrum antimicrobials through the present century.

Tetracycline Antibiotics: Mode of Action, Applications, Molecular Biology, and Epidemiology of Bacterial Resistance

Bifidobacterium spp. are becoming increasingly popular in food products, in particular dairy products, due to their history of safe use and the accumulating clinical evidence for their human health-promoting properties as probiotics. If probiotic cultures are incorporated into fermented milks with a specific health claim, a minimum of 106 cfu g−1 are required and therefore reliable methods are essential to monitor their survival and viability following production and during storage. Since most commercially available probiotic products contain a number of bacterial species, it is important to use a medium which promotes the growth of the bacterial group of interest while also inhibiting the growth of starter and other probiotic bacteria present. Indeed, for any culture-dependent enumeration method, the basic prerequisite is its ability to elect and select the target microorganism from the background microflora. This review will detail the elective and selective media used to enumerate bifidobacteria in foods with emphasis on selective media, given the likelihood of water and food products having a bifidobacteria component that is not numerically dominant. Numerous selective agents used for the isolation of bifidobacteria from various environments and food samples are also discussed, as is their suitability for enumerating bifidobacteria from foods and water. It is apparent that no single medium is suitable for the enumeration of all species of bifidobacteria from water and food; however, it appears that the following media, supplemented with mupirocin, are suitable for the selective enumeration of bifidobacteria: de Man Rogosa and Sharpe agar (de Man et al., 1960) supplemented with cysteine hydrochloride, trans-galactosylated oligosaccharide propionate agar, trypticase phytone yeast or reinforced clostridial agar.

Chapter 10:Culture Media for the Detection and Enumeration of Bifidobacteria in Food Production

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SHORT COMMUNICATION Molecular Analysis of the Replication Origin of the Lactococcus lactis Plasmid pCI305

Increasing evidence is emerging about the influence of the gut microbiota on the brain-gut axis, which has led to the concept of the brain-gut-enteric microbiota axis. In order to study this signaling mechanism, a number of approaches have been used involving animal models which examine the influence of the microbiota on brain function as discussed below. This review focuses on the influence of the gut microbiota on the gut-brain axis, bioactive metabolite production, and the use of probiotics to modulate metabolism and behavior.

Effects of the intestinal microbiota on behavior and brain biochemistry.

Developing fields in food biotechnology

Irish Research Council (Postgraduate scholarship Enterprise Partnership Scheme (in collaboration with Alimentary Health, Ltd.); Science Foundation Ireland (SFI grant no. 07/CE/B1368, Alimentary Pharmabiotic Centre, Investigator award (07/IN.1/B1780))

Gerald F. Fitzgerald

Papers

Chapter 10:Culture Media for the Detection and Enumeration of Bifidobacteria in Food Production

SHORT COMMUNICATION Molecular Analysis of the Replication Origin of the Lactococcus lactis Plasmid pCI305

Effects of the intestinal microbiota on behavior and brain biochemistry.

Developing fields in food biotechnology

Draft Genome Sequence of Lactobacillus crispatus EM-LC1, an Isolate with Antimicrobial Activity Cultured from an Elderly Subject.