Monday, January 16, 2012

Hot off the presses! Feb 01 Nat Rev Microbiol

The Feb 01 issue of the Nat Rev Microbiol is now up on Pubget (About Nat Rev Microbiol): if you're at a subscribing institution, just click the link in the latest link at the home page. (Note you'll only be able to get all the PDFs in the issue if your institution subscribes to Pubget.)

Latest Articles Include:

  • - Nat Rev Microbiol 10(2):79 (2012)
  • HIV: Tagged for destruction | PDF (394 KB)
    - Nat Rev Microbiol 10(2):81 (2012)
    Two papers recently published in Nature show that the HIV-1 accessory protein virion infectivity factor (Vif) co-opts a transcription cofactor into the ubiquitin ligase complex that tags the host restriction factor APOBEC3G (A3G) for destruction by the proteasome, thus maintaining viral infectivity.
  • Bacterial pathogenesis: A balancing act for LLO and PLC | PDF (307 KB)
    - Nat Rev Microbiol 10(2):82 (2012)
    The pore-forming toxin listeriolysin O (LLO), which facilitates escape from the phagosome of host cells, protects Listeria monocytogenes from reactive oxygen species (ROS), according to a recent study.
  • Marine microbiology: SAR86: streamlined for success | PDF (232 KB)
    - Nat Rev Microbiol 10(2):82 (2012)
    A recent ISME Journal paper presents a genomic analysis of the abundant marine gammaproteobacterial clade SAR86, revealing metabolic details that shed light on the role of these organisms in the ocean.
  • Antimicrobials: Reversing resistance with phage | PDF (284 KB)
    - Nat Rev Microbiol 10(2):83 (2012)
    The threat from antibiotic resistance has seen interest in phage therapy rekindled in recent years. Writing in Applied and Environmental Microbiology, Edgar et al.
  • Bacterial physiology: Environment shapes magnetic personality | PDF (189 KB)
    - Nat Rev Microbiol 10(2):84 (2012)
    Some aquatic bacteria orient and swim along geomagnetic fields by producing magnetosomes — intracellular, membrane-bound magnetic crystals made of the minerals magnetite (Fe3O4) or greigite (Fe3S4). Although a number of magnetite-producing species have been isolated and characterized, no greigite-producing species have been isolated and grown in pure culture.
  • Bacterial development: Racing to decide | PDF (337 KB)
    - Nat Rev Microbiol 10(2):84 (2012)
    Cells that can differentiate towards one fate or another occur across species. However, understanding how an individual cell 'chooses' its fate is challenging; cross-regulation between competing programmes has been suggested as a mechanism, but recent work in bacteria shows that fate can depend on which programme wins a molecular race.
  • HIV: Successful protection | PDF (99 KB)
    - Nat Rev Microbiol 10(2):82 (2012)
    Barouch et al. report on the development of a vaccine that protects rhesus macaques against the acquisition of neutralization-resistant simian immunodeficiency virus (SIV).

  • - Nat Rev Microbiol 10(2):82 (2012)

  • - Nat Rev Microbiol 10(2):82 (2012)
  • Sequencing parasite populations | PDF (1,012 KB)
    - Nat Rev Microbiol 10(2):85 (2012)
    This month's Genome Watch highlights how a population study, in conjunction with a reference genome, can identify the evolutionary features that contribute to drug resistance in a protozoan parasite.
  • In the news | PDF (300 KB)
    - Nat Rev Microbiol 10(2):86 (2012)
    Antibiotics controversy On 22 December 2011, the US Food and Drug Administration (FDA) announced that it will not regulate the use of antibiotics in animal feed that is used for livestock intended for human consumption. Banning the use of antibiotics to treat healthy livestock was originally proposed in 1977 following concerns that this use would decrease antibiotic effectiveness and lead to the generation of antibiotic-resistant bacteria. In particular, an advisory committee had recommended immediately withdrawing approval for the use of penicillin and of subtherapeutic doses of tetracycline in animal feed. In the announcement in the Federal Register, the FDA said that it now plans to allow the industry to self-regulate and "focus its efforts for now on the potential for voluntary reform and the promotion of the judicious use of antimicrobials in the interest of public health". However, in an announcement on 4 January 2012, the FDA issued an order prohibiting certain uses of cephalosporins (for example, using unapproved doses or using cephalosporins intended for other species) in cattle, swine, chickens and turkeys, effective 5 April 2012. A similar, but stricter, proposal had been made in 2008; however, it had been strongly opposed by ranchers and farmers. The aim of this new order is to preserve the effectiveness of cephalosporins and prevent the development of resistant bacteria. The Guardian/NY Times/Federal Register Soothing the bite Researchers have developed a gel that can be applied to tick bites to prevent Lyme borreliosis, a disease that is caused by Borrelia spp. and for which there is currently no prophylactic treatment or vaccine. The gel has been developed by a research group in the Fraunhofer Institute for Cell Therapy and Immunology IZI, Leipzig, Germany, together with the Swiss company Ixodes AG and the Institute for Infectious Diseases and Zoonoses of the Ludwig Maximilian University in Munich, Germany. The active ingredient of the gel is the antibiotic azithromycin, which can kill the bacteria locally on the skin, thereby preventing the development of disease. The researchers obtained promising results in preclinical studies, as the gel was effective in mice even 5 days after the tick bite. They are now carrying out Phase III clinical studies, testing the gel on individuals with proven tick bites. However, the researchers emphasize that the gel is only prophylactic and would not be effectiv! e on established infections. Science Daily The rules of attraction The composition of the skin microbiota affects our attractiveness to mosquitoes, according to a recent study. Microbial communities in the skin are known to affect the production of human odours, which are key determinants of attractiveness to the mosquito Anopheles gambiae sensu stricto, one of the most important vectors of malaria in Africa. The study, carried out by Smallegange and colleagues from the Wageningen University and Research Centre in the Netherlands, found that humans with a higher abundance but lower diversity of bacteria on their skin are more attractive to this mosquito than those with a higher diversity of skin bacteria. The researchers postulate that more diverse skin bacteria may act as a defence system against malaria by emitting compounds that interfere with normal attraction to A. gambiae s.s., which, in turn, would make the individuals that carry them less attractive to the mosquitoes. This finding could potentially lead to the development of prophyl! actics against malaria infection that work by manipulating the composition of the skin microbiota and thereby reducing a person's attractiveness to the vectors. PLoS ONE UV rays not always bad? A study has proposed that ultraviolet (UV) rays from the sun can prevent the spread of varicella–zoster virus (VZV), potentially by inactivating the virus on the skin before it transmits to another person. VZV, which causes chickenpox, was known to have geographical patterns of prevalence, with children living in the tropics showing lower rates of infection than those living in temperate areas. Although differences in heat and humidity were thought to underlie this pattern, Philip Rice, a researcher at St George's University in London, UK, hypothesized that UV rays are the climatic factor responsible, as they show the largest difference between tropical and temperate regions. To examine this possibility, he plotted data from previously published studies on VZV prevalence patterns against a range of climatic factors and found that UV rays showed the best correlation with virus prevalence. This observation may also explain why, in temperate regions, VZV transmission is lower! during the summer months, when UV radiation is at its highest. Virol. J./BBC Outbreak news Influenza. The first case of human bird flu in China since June 2010 has been reported. A man has died in Shenzhen, Guangdong Province, China, after becoming infected with H5N1 — the man is thought to have had no direct contact with poultry and not to have travelled outside Shenzhen. Health officials in neighbouring Hong Kong have urged vigilance to prevent new infections, and imports of poultry and poultry products have been suspended. 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).
  • Of ticks, mice and men: understanding the dual-host lifestyle of Lyme disease spirochaetes
    - Nat Rev Microbiol 10(2):87 (2012)
    In little more than 30 years, Lyme disease, which is caused by the spirochaete Borrelia burgdorferi, has risen from relative obscurity to become a global public health problem and a prototype of an emerging infection. During this period, there has been an extraordinary accumulation of knowledge on the phylogenetic diversity, molecular biology, genetics and host interactions of B. burgdorferi. In this Review, we integrate this large body of information into a cohesive picture of the molecular and cellular events that transpire as Lyme disease spirochaetes transit between their arthropod and vertebrate hosts during the enzootic cycle.
  • Proteasomes and protein conjugation across domains of life
    - Nat Rev Microbiol 10(2):100 (2012)
    Like other energy-dependent proteases, proteasomes, which are found across the three domains of life, are self-compartmentalized and important in the early steps of proteolysis. Proteasomes degrade improperly synthesized, damaged or misfolded proteins and hydrolyse regulatory proteins that must be specifically removed or cleaved for cell signalling. In eukaryotes, proteins are typically targeted for proteasome-mediated destruction through polyubiquitylation, although ubiquitin-independent pathways also exist. Interestingly, actinobacteria and archaea also covalently attach small proteins (prokaryotic ubiquitin-like protein (Pup) and small archaeal modifier proteins (Samps), respectively) to certain proteins, and this may serve to target the modified proteins for degradation by proteasomes.
  • Candida albicans morphogenesis and host defence: discriminating invasion from colonization
    - Nat Rev Microbiol 10(2):112 (2012)
    Candida albicans is a common fungal pathogen of humans that colonizes the skin and mucosal surfaces of most healthy individuals. Until recently, little was known about the mechanisms by which mucosal antifungal defences tolerate colonizing C. albicans but react strongly when hyphae of the same microorganism attempt to invade tissue. In this Review, we describe the properties of yeast cells and hyphae that are relevant to their interaction with the host, and the immunological mechanisms that differentially recognize colonizing versus invading C. albicans.
  • From the regulation of peptidoglycan synthesis to bacterial growth and morphology
    - Nat Rev Microbiol 10(2):123 (2012)
    How bacteria grow and divide while retaining a defined shape is a fundamental question in microbiology, but technological advances are now driving a new understanding of how the shape-maintaining bacterial peptidoglycan sacculus grows. In this Review, we highlight the relationship between peptidoglycan synthesis complexes and cytoskeletal elements, as well as recent evidence that peptidoglycan growth is regulated from outside the sacculus in Gram-negative bacteria. We also discuss how growth of the sacculus is sensitive to mechanical force and nutritional status, and describe the roles of peptidoglycan hydrolases in generating cell shape and of D-amino acids in sacculus remodelling.
  • The dependence of viral RNA replication on co-opted host factors
    - Nat Rev Microbiol 10(2):137 (2012)
    Positive-sense RNA ((+)RNA) viruses such as hepatitis C virus exploit host cells by subverting host proteins, remodelling subcellular membranes, co-opting and modulating protein and ribonucleoprotein complexes, and altering cellular metabolic pathways during infection. To facilitate RNA replication, (+)RNA viruses interact with numerous host molecules through protein–protein, RNA–protein and protein–lipid interactions. These interactions lead to the formation of viral replication complexes, which produce new viral RNA progeny in host cells. This Review presents the recent progress that has been made in understanding the role of co-opted host proteins and membranes during (+)RNA virus replication, and discusses common themes employed by different viruses.
  • Immune reconstitution inflammatory syndrome: the trouble with immunity when you had none
    - Nat Rev Microbiol 10(2):150 (2012)
    Some individuals who are infected with HIV rapidly deteriorate shortly after starting antiretroviral therapy, despite effective viral suppression. This reaction, referred to as immune reconstitution inflammatory syndrome (IRIS), is characterized by tissue-destructive inflammation and arises as CD4+ T cells re-emerge. It has been proposed that IRIS is caused by a dysregulation of the expanding population of CD4+ T cells specific for a co-infecting opportunistic pathogen. Here, we argue that IRIS instead results from hyper-responsiveness of the innate immune system to T cell help, a mechanism that may be shared by the many manifestations of IRIS that occur following the reversal of other types of immunosuppression in pathogen-infected hosts.

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