Latest Articles Include:
-
- Nat Rev Microbiol 10(1):1 (2012)
- Antimicrobials: Promoting tolerance | PDF (225 KB)
- Nat Rev Microbiol 10(1):2 (2012)
Tolerance to antibiotics in genetically susceptible bacteria poses major problems for the treatment of infectious diseases and provides a source of resistant strains. Two papers published in Science now provide insight into the diverse mechanisms underlying this process. - Parasitology: Basigin opens the door to malaria | PDF (412 KB)
- Nat Rev Microbiol 10(1):3 (2012)
Plasmodium falciparum is one of the Plasmodium species that cause malaria, a disease that is initiated by parasitic infection of erythrocytes. Several host receptors and P. falciparum - Microbiome: Tipping the balance | PDF (169 KB)
- Nat Rev Microbiol 10(1):3 (2012)
A recent Cell Host & Microbe paper reveals that Porphyromonas gingivalis, the key bacterial trigger for periodontitis, disrupts the homeostasis between the host and the commensal oral microbiota, thereby tipping the balance towards inflammatory disease. - Symbiosis: Sheltered bacteria lose their senses | PDF (167 KB)
- Nat Rev Microbiol 10(1):4 (2012)
Owing to their stable association with a host organism, bacterial endosymbionts often exhibit extensive reduction in their genomes as they lose genes associated with the ability to adapt to changes in the environment. Interestingly, Sodalis glossinidius, an endosymbiont of the tsetse fly, has maintained intact copies of genes that are associated with virulence in many bacterial pathogens. - Immune evasion: Size does matter | PDF (235 KB)
- Nat Rev Microbiol 10(1):4 (2012)
Bacteria use numerous strategies to resist killing by the host immune system. Dalia and Weiser now add to this list of strategies by revealing that Streptococcus pneumoniae avoids complement-mediated killing by minimizing its size (chain length). - Bacterial evolution: Parallel lives | PDF (252 KB)
- Nat Rev Microbiol 10(1):5 (2012)
The increased availability of high-throughput whole-genome sequencing has facilitated analysis of the transmission and evolution of bacterial pathogens during disease outbreaks. To date, however, it has been difficult to separate adaptive mutations, which confer a benefit, from neutral mutations, which have no impact on fitness. - Virology: Tetherin lets HCMV in | PDF (90 KB)
- Nat Rev Microbiol 10(1):4 (2012)
Tetherin (also known as BST2) is known to inhibit the release of numerous enveloped viruses. Surprisingly, this study shows that, in the case of human cytomegalovirus (HCMV), tetherin has a beneficial role for the virus, enhancing its entry into the host cell. -
- Nat Rev Microbiol 10(1):4 (2012)
-
- Nat Rev Microbiol 10(1):4 (2012)
- The battle of the SNPs | PDF (135 KB)
- Nat Rev Microbiol 10(1):6 (2012)
This month's Genome Watch highlights new perspectives on polygenic adaptation and its consequences for fitness in microbial populations. - In the news | PDF (222 KB)
- Nat Rev Microbiol 10(1):7 (2012)
Arrival of an amphibian assassin Contact between previously isolated populations of the fungus Batrachochytrium dendrobatidis may have led to recombination events that resulted in the generation of the hypervirulent strain implicated in current mass amphibian extinctions. B. dendrobatidis is a pathogenic fungus found throughout the world and has emerged as the primary cause of global loss of amphibian biodiversity. However, little is known about its origins and spread. Using comparative population genomics, Matthew Fisher and colleagues identified three deeply diverged fungal lineages associated with amphibians, two of which have been spread to multiple continents by the amphibian trade. They found that isolates from one lineage (BdGPL) are hypervirulent and have emerged across at least five continents during the past century. Importantly, they identified hallmarks of genetic recombination in BdGPL which suggest that it arose following a meeting between previously genetically isolated allopatric populations! . Proc. Natl Acad. Sci. USA/New York Times Turning the tide against AIDS? Both the number of AIDS-related deaths per year and the number of new HIV infections per year have decreased by more than 20% since their respective peaks in 2006 and 1997, according to the latest UNAIDS report. The decreases are mainly the result of better access to treatment, with the biggest advances seen in sub-Saharan Africa, where improved access to antiretroviral drugs has been supported by changes in sexual behaviour and increasing acceptance of male circumcision. The report also highlights exceptions to the global trend, with the number of new HIV infections still increasing in the countries of the former Soviet Union and in Central Asia. Furthermore, new data from the Health Protection Agency in the United Kingdom show an increase in the number of infections, with 91,500 people living with HIV in 2010, up 5,000 on the previous year. Although the total number of HIV-infected individuals worldwide now stands at over 34 million, a record level, according to the UNAIDS! report the latest figures suggest that, although the epidemic is not over, it is certainly conceivable that "the end might be in sight if countries invest smartly". However, with news that the Global Fund to Fight AIDS, TB and Malaria will award no new grants until 2014, the international financial situation might undermine the advances made in tackling HIV infections in recent years. The Global Fund provides about one-quarter of the funds for fighting HIV and AIDS, but when it asked international donors for $20 billion, it received just $11.5 billion. BBC/Washington Post/Guardian Lolli-pox idea widely panned A posting on the social media website Facebook offering to sell lollipops infected with varicella–zoster virus (which causes chicken pox) has brought attention to the ongoing practice of 'pox parties' and drawn concern amongst scientists and health care professionals. The lollipops were thought to have been contaminated with saliva from children infected with the virus and were priced at US$50 each. The posts have now been removed from the site, and there is no evidence that any lollipops were actually bought. Infections transmitted to children through sharing of contaminated items are believed by many parents to provide their children with stronger immunity while avoiding the perceived hazards associated with vaccines. However, public health experts have warned that not only is the practice likely to be ineffective for transferring varicella–zoster virus, which requires living cells to survive, but also it will increase the risk of transmitting hepatitis B virus and gro! up A streptococcal infections. Science /New York Times/Los Angeles Times Early-bird antibiotics Treatment of filariasis with antibiotics was known to lead to a reduction in the burden of microfilarial nematode worms, interrupting their transmission, but how this occurred was something of a mystery. Now, a paper from Mark Taylor and colleagues reveals how using antibiotics to target and deplete the bacterial endosymbiont Wolbachia results in antifilarial activity. They found that antibiotic-mediated depletion of Wolbachia from adult Brugia malayi worms led to extensive apoptosis in the adult germline and in the somatic cells of embryos, microfilariae and fourth-stage larvae, resulting in long-term sterilization. Interestingly, the cells that undergo apoptosis do not contain the bacteria, suggesting that factors released from Wolbachia-infected cells in the hypodermal chords upon antibiotic treatment induce apoptosis in a non-cell-autonomous manner. PLoS Pathog. Outbreak News Influenza. In the past 3 months, ten people in the United States have been infected by a new swine flu variant. The new strain, termed S-OtrH3N2, combines the H3N2 influenza A virus that circulates in North American pigs with the H1N1 virus that caused the 2009 swine flu outbreak. In the first seven infections, either the patients or their close associates had been in contact with pigs. However, the three most recent cases were in children in Iowa, none of which had any recent exposure to pigs. According to the CDC, a sample of the virus that would be suitable for production of a human vaccine has been developed and sent to vaccine manufacturers. Bloomberg/ABC News Polio. There has been a four-fold increase in the number of cases of polio in Nigeria, with 43 reported cases this year compared with just 11 last year. Cases have also been reported in Mali, Niger and Ivory Coast, suggesting that the outbreak has spread from Nigeria to neighbouring countries. BBC In the News was compiled with the assistance of David Ojcius, University of California, Merced, USA. David's links to infectious disease news stories can be accessed on his Twitter page (@Ojcius). - Nucleoid occlusion and bacterial cell division
- Nat Rev Microbiol 10(1):8 (2012)
The bacterial cell cycle requires the tight regulation and precise coordination of several sophisticated cellular processes. Prominent among them is the formation of the dividing wall or septum, which has to take place at the right time and place to ensure equality of the progeny and integrity of the genome. Nucleoid occlusion is a defence mechanism that prevents the chromosome from being bisected and broken by the division septum. It does so by preventing Z ring formation near the nucleoid, which also helps to determine the location of septation. - Extreme genome reduction in symbiotic bacteria
- Nat Rev Microbiol 10(1):13 (2012)
Since 2006, numerous cases of bacterial symbionts with extraordinarily small genomes have been reported. These organisms represent independent lineages from diverse bacterial groups. They have diminutive gene sets that rival some mitochondria and chloroplasts in terms of gene numbers and lack genes that are considered to be essential in other bacteria. These symbionts have numerous features in common, such as extraordinarily fast protein evolution and a high abundance of chaperones. Together, these features point to highly degenerate genomes that retain only the most essential functions, often including a considerable fraction of genes that serve the hosts. These discoveries have implications for the concept of minimal genomes, the origins of cellular organelles, and studies of symbiosis and host-associated microbiota. - The myriad roles of cyclic AMP in microbial pathogens: from signal to sword
- Nat Rev Microbiol 10(1):27 (2012)
All organisms must sense and respond to their external environments, and this signal transduction often involves second messengers such as cyclic nucleotides. One such nucleotide is cyclic AMP, a universal second messenger that is used by diverse forms of life, including mammals, fungi, protozoa and bacteria. In this review, we discuss the many roles of cAMP in bacterial, fungal and protozoan pathogens and its contributions to microbial pathogenesis. These roles include the coordination of intracellular processes, such as virulence gene expression, with extracellular signals from the environment, and the manipulation of host immunity by increasing cAMP levels in host cells during infection. - Should we stay or should we go: mechanisms and ecological consequences for biofilm dispersal
- Nat Rev Microbiol 10(1):39 (2012)
In most environments, bacteria reside primarily in biofilms, which are social consortia of cells that are embedded in an extracellular matrix and undergo developmental programmes resulting in a predictable biofilm 'life cycle'. Recent research on many different bacterial species has now shown that the final stage in this life cycle includes the production and release of differentiated dispersal cells. The formation of these cells and their eventual dispersal is initiated through diverse and remarkably sophisticated mechanisms, suggesting that there are strong evolutionary pressures for dispersal from an otherwise largely sessile biofilm. The evolutionary aspect of biofilm dispersal is now being explored through the integration of molecular microbiology with eukaryotic ecological and evolutionary theory, which provides a broad conceptual framework for the diversity of specific mechanisms underlying biofilm dispersal. Here, we review recent progress in this emerging fiel! d and suggest that the merging of detailed molecular mechanisms with ecological theory will significantly advance our understanding of biofilm biology and ecology. - Conventional and unconventional mechanisms for capping viral mRNA
- Nat Rev Microbiol 10(1):51 (2012)
In the eukaryotic cell, capping of mRNA 5′ ends is an essential structural modification that allows efficient mRNA translation, directs pre-mRNA splicing and mRNA export from the nucleus, limits mRNA degradation by cellular 5′–3′ exonucleases and allows recognition of foreign RNAs (including viral transcripts) as 'non-self'. However, viruses have evolved mechanisms to protect their RNA 5′ ends with either a covalently attached peptide or a cap moiety (7-methyl-Gppp, in which p is a phosphate group) that is indistinguishable from cellular mRNA cap structures. Viral RNA caps can be stolen from cellular mRNAs or synthesized using either a host- or virus-encoded capping apparatus, and these capping assemblies exhibit a wide diversity in organization, structure and mechanism. Here, we review the strategies used by viruses of eukaryotic cells to produce functional mRNA 5′-caps and escape innate immunity. - Emerging molecular insights into the interaction between probiotics and the host intestinal mucosa
- Nat Rev Microbiol 10(1):66 (2012)
Probiotic bacteria can modulate immune responses in the host gastrointestinal tract to promote health. The genomics era has provided novel opportunities for the discovery and characterization of bacterial probiotic effector molecules that elicit specific responses in the intestinal system. Furthermore, nutrigenomic analyses of the response to probiotics have unravelled the signalling and immune response pathways which are modulated by probiotic bacteria. Together, these genomic approaches and nutrigenomic analyses have identified several bacterial factors that are involved in modulation of the immune system and the mucosal barrier, and have revealed that a molecular 'bandwidth of human health' could represent a key determinant in an individual's physiological responsiveness to probiotics. These approaches may lead to improved stratification of consumers and to subpopulation-level probiotic supplementation to maintain or improve health, or to reduce the risk of disease. - Correspondence: Sputnik and Mavirus: more than just satellite viruses
- Nat Rev Microbiol 10(1):88 (2012)
In a recent Comment (Virophages or satellite viruses? Nature Rev. Microbiol.9 762–763 (2011)
No comments:
Post a Comment