MicrobiologyBytes

My Leicester colleague Catherine Pashley has done a lot of work in this area, so I was interested in this recent minireview in PLOS Pathogens.

• What Is Asthma?
• Why Do Fungi Make Spores? And a Guide to Terminology
• Do Fungal Spores Cause Asthma?
• Which Species Are Associated with Asthma?
• If Identification to Species Matters, Will New Tools Provide Needed Data?

Asthma and the Diversity of Fungal Spores in Air. (2013) PLoS Pathog 9(6): e1003371. doi:10.1371/journal.ppat.1003371
The diversity of fungal spores in air is vast, but research on asthma focuses on a handful of easily identified, culturable species. Ecologists are developing new tools to probe communities and identify the full complement of fungi in habitats. These tools may enable identification of novel asthma triggers, but scientists involved in public health or medicine rarely interact with mycologists focused on ecology. With this primer, my aim is to facilitate communication by providing doctors with a basic, modern guide to spores, by teaching mycologists the essential facts of asthma, and by providing patients with a succinct summary of what is known about spores and asthma. By highlighting the use of emerging metagenomics technologies in ecology, I intend to illustrate how these tools might be used to more thoroughly understand the potential diversity of fungi involved in asthma.

I’ve spent quite a bit of time in the last week marking exam essays about papillomaviruses, so it’s good to relax by reading a few recent journal articles about …. papillomaviruses ;-)

Animal papillomaviruses. Virology. 24 May 2013 pii: S0042-6822(13)00266-3. doi: 10.1016/j.virol.2013.05.007
We provide an overview of the host range, taxonomic classification and genomic diversity of animal papillomaviruses. The complete genomes of 112 non-human papillomavirus types, recovered from 54 different host species, are currently available in GenBank. The recent characterizations of reptilian papillomaviruses extend the host range of the Papillomaviridae to include all amniotes. Although the genetically diverse papillomaviruses have a highly conserved genomic lay-out, deviations from this prototypic genome organization are observed in several animal papillomaviruses, and only the core ORFs E1, E2, L2 and L1 are present in all characterized papillomavirus genomes. The discovery of papilloma-polyoma hybrids BPCV1 and BPCV2, containing a papillomaviral late region but an early region encoding typical polyomaviral nonstructural proteins, and the detection of recombination breakpoints between the early and late coding regions of cetacean papillomaviruses, could indicate that early and late gene cassettes of papillomaviruses are relatively independent entities that can be interchanged by recombination.

Papillomavirus E6 oncoproteins. 24 May 2013 Virology pii: S0042-6822(13)00248-1. doi: 10.1016/j.virol.2013.04.026
Papillomaviruses induce benign and malignant epithelial tumors, and the viral E6 oncoprotein is essential for full transformation. E6 contributes to transformation by associating with cellular proteins, docking on specific acidic LXXLL peptide motifs found on these proteins. This review examines insights from recent studies of human and animal E6 proteins that determine the three-dimensional structure of E6 when bound to acidic LXXLL peptides. The structure of E6 is related to recent advances in the purification and identification of E6 associated protein complexes. These E6 protein-complexes, together with other proteins that bind to E6, alter a broad array of biological outcomes including modulation of cell survival, cellular transcription, host cell differentiation, growth factor dependence, DNA damage responses, and cell cycle progression.

The eradication of HIV-1 from infected individuals is prevented by the persistence of the virus in a stable reservoir of latently infected CD4+ T cells. Latently infected cells can be found in all HIV-1 infected individuals at a very low frequency and allow the virus to persist despite antiretroviral therapy for the lifetime of an infected patient. Current efforts are focused on identifying small molecules or immune strategies to eliminate these latently infected cells. To assess the efficacy of these elimination strategies in HIV-1 infected patients, we must be able to measure the size of the remaining latent reservoir. While a previous assay can measure the size of this latent reservoir, it is too laborious and costly to be utilized in large-scale HIV-1 eradication trials. A new paper in PLoS Pathogens describes a rapid assay to measure the size of the HIV-1 latent reservoir more amenable to eradication trials.

Rapid Quantification of the Latent Reservoir for HIV-1 Using a Viral Outgrowth Assay. (2013) PLoS Pathog 9(5): e1003398. doi:10.1371/journal.ppat.1003398
HIV-1 persists in infected individuals in a stable pool of resting CD4+ T cells as a latent but replication-competent provirus. This latent reservoir is the major barrier to the eradication of HIV-1. Clinical trials are currently underway investigating the effects of latency-disrupting compounds on the persistence of the latent reservoir in infected individuals. To accurately assess the effects of such compounds, accurate assays to measure the frequency of latently infected cells are essential. The development of a simpler assay for the latent reservoir has been identified as a major AIDS research priority. We report here the development and validation of a rapid viral outgrowth assay that quantifies the frequency of cells that can release replication-competent virus following cellular activation. This new assay utilizes bead and column-based purification of resting CD4+ T cells from the peripheral blood of HIV-1 infected patients rather than cell sorting to obtain comparable resting CD4+ T cell purity. This new assay also utilizes the MOLT-4/CCR5 cell line for viral expansion, producing statistically comparable measurements of the frequency of latent HIV-1 infection. Finally, this new assay employs a novel quantitative RT-PCR specific for polyadenylated HIV-1 RNA for virus detection, which we demonstrate is a more sensitive and cost-effective method to detect HIV-1 replication than expensive commercial ELISA detection methods. The reductions in both labor and cost make this assay suitable for quantifying the frequency of latently infected cells in clinical trials of HIV-1 eradication strategies.

Latest News | W.H.O. Global Alert and Response

1. Coronaviruses are a family of viruses that includes viruses that may cause a range of illnesses in humans, from common cold-type respiratory infections to SARS. Viruses of this family also cause a number of animal diseases.

2. What’s it called again?
Currently being referred to as nCoV or nCoV-2012, this virus has also been called Human Coronavirus-Erasmus Medical Center (hCoV-EMC), or Middle East respiratory syndrome coronavirus (MERS-CoV), and even “Saudi SARS” (it’s not – SARS is a related but different Coronavirus).

3. The first known case of nCoV infection was in a Saudi Arabian man who died in early 2012. This particular strain of coronavirus had not been previously identified in humans. The second confirmed case appeared in early September 2012, involving a 49-year old man in Doha, Qatar who had traveled to Saudi Arabia around the same time that the first case was identified. Currently, at least 40 cases have been confirmed, and 20 of those affected have died. The virus has also been found in Tunisia.

4. Where did it come from?
Bats. (It’s [nearly] always bats.) Bat coronaviruses carried by the genus Pipistrellus that differ from nCoV by as little as 1.8%. The existence of over 50 species of Pipistrellus bats in the Arabian Peninsula suggests that they may be the animal reservoir.

5. Symptoms of nCoV infection include renal failure and severe acute pneumonia, which often result in a fatal outcome. In humans, the virus has a strong tropism for nonciliated bronchial epithelial cells because it uses dipeptidyl peptidase 4 (DPP4, also known as CD26) as a receptor.

6. nCoV can penetrate the bronchial epithelium and evade the innate immune system, signs that it is well-equipped for infecting human cells. This suggests that although nCoV may have jumped from animals to humans very recently, it is as well adapted to infecting the human respiratory tract as other, more familiar human coronaviruses, including the SARS virus and the common cold Coronavirus HCoV-229E.

7. The virus is susceptible to treatment with interferons, immune proteins that have been used successfully to treat other viral diseases, offering a possible method of treatment in the event of a large-scale outbreak.

8. How is it transmitted?
Almost certainly like other respiratory viruses, via aerosol droplets from coughs and sneezes, but possibly also by unwashed hands contaminated with respiratory secretions.

9. Is there a vaccine?
Not yet. It is possible to make vaccines agains Coronaviruses and several SARS vaccines were developed but never put into use because the SARS outbreak died away. It should be possible to make a nCoV vaccine if we need one.

10. Is there any travel advice?
At the moment the World Health Organization says there is no reason to impose any travel restrictions. Travel advice will be kept under review if additional cases occur or when the patterns of transmission become clearer.

11. Are we all going to die?
Probably not. Most of the people who have been infected so far have been older men, often with other medical conditions. The outbreak of Severe Acute Respiratory Syndrome (SARS) in 2003 infected over 8000 people and killed nearly 800 before burning itself out. But SARS didn’t kill us all and it’s unlikely that nCoV will either.

Other things you should know:

• 10 things you should know about H1N1 (swineflu)
• 10 things you should know about E. coli
• 10 things you didn’t know about Schmallenberg virus
• 10 things about Foot and Mouth Disease

There is intense interest in developing a cure for HIV. How such a cure will be quantified and defined is not known. Researchers applied a series of measurements of HIV persistence to the study of an HIV+ adult who has exhibited evidence of cure after a stem cell transplant.

Samples from blood, spinal fluid, lymph node, and gut were analyzed in multiple laboratories using different approaches. No HIV was detected in blood cells, spinal fluid, lymph node, or small intestine, and no infectious virus was recovered from blood. However, HIV was detected in plasma (2 laboratories) and HIV DNA was detected in the rectum (1 laboratory) at levels considerably lower than those expected in antiretroviral treated patients. The occasional, low-level HIV signals might be due to persistent HIV or might reflect false positives. The sensitivity of the current generation of assays to detect HIV RNA, HIV DNA, and infectious virus are close to the limits of detection. Improvements in these tests will be needed for future curative studies.

The lack of rebounding virus after five years without therapy, the failure to isolate infectious virus, and the waning HIV-specific immune responses all indicate that the Berlin Patient has been effectively cured.

Challenges in Detecting HIV Persistence during Potentially Curative Interventions: A Study of the Berlin Patient. (2013) PLoS Pathog 9(5): e1003347. doi:10.1371/journal.ppat.1003347
There is intense interest in developing curative interventions for HIV. How such a cure will be quantified and defined is not known. We applied a series of measurements of HIV persistence to the study of an HIV-infected adult who has exhibited evidence of cure after allogeneic hematopoietic stem cell transplant from a homozygous CCR5Δ32 donor. Samples from blood, spinal fluid, lymph node, and gut were analyzed in multiple laboratories using different approaches. No HIV DNA or RNA was detected in peripheral blood mononuclear cells (PBMC), spinal fluid, lymph node, or terminal ileum, and no replication-competent virus could be cultured from PBMCs. However, HIV RNA was detected in plasma (2 laboratories) and HIV DNA was detected in the rectum (1 laboratory) at levels considerably lower than those expected in ART-suppressed patients. It was not possible to obtain sequence data from plasma or gut, while an X4 sequence from PBMC did not match the pre-transplant sequence. HIV antibody levels were readily detectable but declined over time; T cell responses were largely absent. The occasional, low-level PCR signals raise the possibility that some HIV nucleic acid might persist, although they could also be false positives. Since HIV levels in well-treated individuals are near the limits of detection of current assays, more sensitive assays need to be developed and validated. The absence of recrudescent HIV replication and waning HIV-specific immune responses five years after withdrawal of treatment provide proof of a clinical cure.

Over the last few years, many microbiomes (all of the microbobes found in a particular enviromnet) have been published. Most of these long list of bugs have been purely descriptive, but this knowledge is now starting to pay off by finding out which microbes are associated with particular diseases. In many cases, it’s not as simple as a single organism causing a disease.

For example, take chronic rhinosinusitis, a disease with a significant societal burden, but despite extensive research efforts, an unknown pathophysiology. There is emerging evidence that microorganisms play an important role in the exacerbation and perpetuation of mucosal inflammation:

The microbiome of chronic rhinosinusitis: culture, molecular diagnostics and biofilm detection. (2013) BMC Infectious Diseases, 13:210 doi:10.1186/1471-2334-13-210
Bacteria and fungi are believed to influence mucosal inflammation in chronic rhinosinusitis (CRS). However their presence and relationship to disease is debated. This study used multiple detection methods to compare microbial diversity and microbial abundance in healthy and diseased sinonasal mucosa. The utility of contemporary detection methods is also examined. Sinonasal mucosa was analyzed from 38 CRS and 6 controls. Bacterial and fungal analysis was performed using conventional culture, molecular diagnostics (polymerase chain reaction coupled with electrospray ionization time-of-flight mass spectrometry) and fluorescence in situ hybridization. Microbes were detected in all samples, including controls, and were often polymicrobial. 33 different bacterial species were detected in CRS, 5 in control patients, with frequent recovery of anaerobes. Staphylococcus aureus and Propionibacterium acnes were the most common organisms in CRS and controls, respectively. Using a model organism, FISH had a sensitivity of 78%, and a specificity of 93%. Many species were detected in both CRS and controls however, microbial abundance was associated with disease manifestation. This study highlights some cornerstones of microbial variations in healthy and diseased paranasal sinuses. Whilst the healthy sinus is clearly not sterile, it appears prevalence and abundance of organisms is critical in determining disease. Evidence from high-sensitivity techniques, limits the role of fungi in CRS to a small group of patients. Comparison with molecular analysis suggests that the detection threshold of FISH and culture is related to organism abundance and, furthermore, culture tends to select for rapidly growing organisms.

Or consider the news that antibiotics may ease chronic back pain:

Antibiotic treatment in patients with chronic low back pain and vertebral bone edema (Modic type 1 changes): a double-blind randomized clinical controlled trial of efficacy. (2013) European Spine Journal, 1-11.
The study was a double-blind RCT with 162 patients whose only known illness was chronic LBP of greater than 6 months duration occurring after a previous disc herniation and who also had bone edema demonstrated as Modic type 1 changes in the vertebrae adjacent to the previous herniation. Patients were randomized to either 100 days of antibiotic treatment (Bioclavid) or placebo and were blindly evaluated at baseline, end of treatment and at 1-year follow-up. Primary outcome, disease-specific disability, lumbar pain. Secondary outcome leg pain, number of hours with pain last 4 weeks, global perceived health, EQ-5D thermometer, days with sick leave, bothersomeness, constant pain, magnetic resonance image (MRI). 144 of the 162 original patients were evaluated at 1-year follow-up. The two groups were similar at baseline. The antibiotic group improved highly statistically significantly on all outcome measures and improvement continued from 100 days follow-up until 1-year follow-up. At baseline, 100 days follow-up, 1-year follow-up the disease-specific disability-RMDQ changed: antibiotic 15, 11, 5.7; placebo 15, 14, 14. Leg pain: antibiotics 5.3, 3.0, 1.4; placebo 4.0, 4.3, 4.3. Lumbar pain: antibiotics 6.7, 5.0, 3.7; placebo 6.3, 6.3, 6.3. For the outcome measures, where a clinically important effect size was defined, improvements exceeded the thresholds, and a trend towards a dose–response relationship with double dose antibiotics being more efficacious. The antibiotic protocol in this study was significantly more effective for this group of patients (CLBP associated with Modic I) than placebo in all the primary and secondary outcomes.

In treating chronic diseases such as these, those long lists of organisms associated with certain diseases states is going to start paying off over the next few years.

“Scholars have argued that in risk communication a dilemma exists between the media functions of informing the media audience about rational risk behavior, and providing an arena for public deliberation about risk. Optimizing the information function would suggest that media provide clear, unanimous advice without creating confusion by reporting uncertainty and controversy. Optimizing the deliberative function, in contrast, would require media to include different (even contradictory) voices. A similar dilemma exists between incompatible expectations of different fractions of the audience. Part of the audience may trust the media to provide the best available advice. These audience members may be prepared to take the mediated advice at face value, not wanting to be unsettled by controversy and uncertainty. But another part of the audience may prefer to learn about the full spectrum of opinions, including outsider views, and may want to develop their own conclusions on whom to trust and whose advice to follow. Presenting only the mainstream view may motivate members of that part of the audience to seek information in alternative channels – such as blogs or rumors.”

Similar challenges but different responses: Media coverage of measles vaccination in the UK and China. (2012) Public Understanding of Science. doi: 10.1177/0963662512445012
For several decades scholars have studied media reporting on scientific issues that involve controversy. Most studies so far have focused on the western world. This article tries to broaden the perspective by considering China and comparing it to a western country. A content analysis of newspaper coverage of vaccination issues in the UK and China shows, first, that the government-supported ‘mainstream position’ dominates the Chinese coverage while the British media frequently refer to criticism and controversy. Second, scientific expertise in the British coverage is represented by experts from the health and science sector but by experts from health agencies in the Chinese coverage. These results are discussed with respect to implications for risk communication and scientists’ involvement in public communication.

The ongoing dance between a virus and its host shapes how the virus evolves. While human adenoviruses typically cause mild infections, recent reports have described newly characterized adenoviruses that cause severe, sometimes fatal human infections. A new paper describes a systems biology approach to show how evolution has affected the disease potential of a recently identified novel human adenovirus. A comprehensive understanding of virus evolution and pathogenicity is essential to our capacity to foretell the potential impact on human disease for new and emerging viruses.

Predicting the next eye pathogen: analysis of a novel adenovirus. (2013) MBio. 4(2): e00595-12. doi: 10.1128/mBio.00595-12
For DNA viruses, genetic recombination, addition, and deletion represent important evolutionary mechanisms. Since these genetic alterations can lead to new, possibly severe pathogens, we applied a systems biology approach to study the pathogenicity of a novel human adenovirus with a naturally occurring deletion of the canonical penton base Arg-Gly-Asp (RGD) loop, thought to be critical to cellular entry by adenoviruses. Bioinformatic analysis revealed a new highly recombinant species D human adenovirus (HAdV-D60). A synthesis of in silico and laboratory approaches revealed a potential ocular tropism for the new virus. In vivo, inflammation induced by the virus was dramatically greater than that by adenovirus type 37, a major eye pathogen, possibly due to a novel alternate ligand, Tyr-Gly-Asp (YGD), on the penton base protein. The combination of bioinformatics and laboratory simulation may have important applications in the prediction of tissue tropism for newly discovered and emerging viruses.

tldr; = your armpits = lunch for bacteria

The human skin exhibits a diversity of ecological niches varying in moisture, the availability of nutrients, and the presence of host- and bacteria-derived antimicrobial peptides. In general, skin regions can be classified as dry, sebaceous, or moist environments with specifically adapted organisms establishing a distinct microbial profile characteristic for each topographical region. 16S rDNA profiling of the skin microbiota in the course of the Human Microbiome Project shed the first light on the community structure at different skin sites independent of microbial culture.

In moist areas such as the armpit (in medispeak, the “axilla”), Corynebacterium and Staphylococcus dominate the bacterial flora, which was demonstrated by culture-based approaches. The axillary region is a specific habitat and differs significantly from other body parts because it harbors hair follicles with sebaceous glands and a high density of sweat glands. In this environment nutrients are readily available, which allows for dense bacterial colonization reaching up to 10⁶ cells per cm². Different types of sweat glands are present including eccrine and apoeccrine glands which are responsible for sweating when you’re hot. Apocrine glands, so-called scent glands, contribute to the high density of nutrients. They secret a milky odorless fluid consisting of electrolytes, steroids, proteins, vitamins, and a variety of lipid compounds. Despite the fact that the exact composition of apocrine sweat is currently unknown due to insufficient availability of pure samples, the microbial biotransformation of these secreted nutrients in the human axilla undoubtedly leads to the development of characteristic and individual odor profiles. Perception and pleasantness of specific odor compounds have been reported to correlate with gender, sexual orientation, and the use of oral contraceptives.

It is of particular interest for the cosmetic industry to understand body-odor formation mechanisms to be able to design deodorants which specifically target them. The classic functional mechanism of deodorants is the depletion of cutaneous bacteria employing unspecific antimicrobial agents. This can cause skin irritations upon very frequent usage not only due to the direct topical action of alcoholic or organic substances. Also, disruption of the integrity of the skin microbiota may have negative effects on the host in terms of health because symbiotic and commensal bacteria participate in immune defense against pathogens. This article gives an overview of the biochemical origin of human axillary odor and the taxonomic composition of the axillary microbiota based on recent data generated with next-generation sequencing techniques.

Daily battle against body odor: towards the activity of the axillary microbiota. Trends in Microbiology. 05 April 2013 doi: 10.1016/j.tim.2013.03.002
The microbial community of the human axilla plays a key role in the formation of axillary odor by biotransformation of odorless natural secretions into volatile odorous molecules. Culture-based microbiological and biochemical studies have allowed the characterization of the axillary microbiota, but the advent of next-generation culture-independent DNA sequencing approaches has provided an unprecedented depth of data regarding the taxonomic composition of the axillary microbiota and intra- and interindividual variation. However, the physiological activity of the microbiota of an individual and its variation under different environmental conditions remains largely unknown. Thus, metatranscriptomics represents a promising technique to identify specific metabolic activities in the axillary microbiota linked to individual differences in body odor.