Preparation of pH‐stimuli‐responsive PEG–TGA/TGH‐capped CdTe QDs and their application in cell labeling

A pH‐sensitive and double functional nanoprobe was designed and synthesized in a water‐soluble system using thioglycolic acid (TGA) and mercapto‐acetohydrazide (TGH) as the stabilizers. TGA is biocompatible because the carboxyl group is easily linked to biological macromolecules. At the same time, the hydrazide on TGH reacts with the aldehyde on poly(ethylene glycol) (PEG) and forms a hydrazone bond. The hydrazone bond ruptured at specific pH values and exhibited pH‐stimuli‐responsive characteristics. As an optical imaging probe, the PEG–TGA/TGH‐capped CdTe quantum dots (QDs) had high quality, with a fluorescence efficiency of 25–30%, and remained stable for at least five months. This pH‐responsive factor can be used for the effective release of CdTe QDs under the acidic interstitial extracellular environment of tumor cells. This allows the prepared pH‐stimuli‐responsive nanoprobes to show fluorescence signals for use in cancer cell imaging. Copyright © 2014 John Wiley & Sons, Ltd.     

A label‐free fluorescence method for detection of ureC gene and diagnosis of Helicobacter pylori infection

The feasibility of using a polymerase chain reaction (PCR)‐based label‐free DNA sensor for the detection of Helicobacter pylori is investigated. In particular, H. pylori ureC gene, a specific H. pylori nucleic acid sequence, was selected as the target sequence. In the presence of ureC gene, the target DNA could be amplified to dsDNA with much higher detectable levels. After added the SYBR green I (SGI), the sensing system could show high fluorescence. Thus, the target DNA can be detected by monitoring the change of fluorescence intensity of sensing system. The clinical performance of this method was determined by comparing it with another conventional technique urea breath test (UBT). The result also showed good distinguishing ability between negative and positive patient, which was in good agreement with that obtained by the UBT. It suggests that the label‐free fluorescence‐based method is more suitable for infection confirmation test of H. pylori. This approach offers great potential for simple, sensitive and cost‐effective identification of H. pylori infection.     

Enzyme‐enabled responsive surfaces for anti‐contamination materials

Many real‐life stains have origins from biological matters including proteins, lipids, and carbohydrates that act as gluing agents binding along with other particulates or microbes to exposed surfaces of automobiles, furniture, and fabrics. Mimicking naturally occurring self‐defensive processes, we demonstrate in this work that a solid surface carrying partially exposed enzyme granules protected the surface in situ from contamination by biological stains and fingerprints. Attributed to the activities of enzymes which can be made compatible with a wide range of materials, such anti‐contamination and self‐cleaning functionalities are highly selective and efficient toward sticky chemicals. This observation promises a new mechanism in developing smart materials with desired anti‐microbial, self‐reporting, self‐cleaning, or self‐healing functions. Biotechnol. Bioeng. 2013; 110: 1805–1810. © 2013 Wiley Periodicals, Inc.     

Lysozyme‐associated bactericidal activity in the ejaculate of a wild passerine

Numerous antibacterial substances have been identified in the ejaculates of animals and are suggested to protect sperm from bacterial‐induced damage in both the male and female reproductive tracts. Lysozymes, enzymes that exhibit bactericidal activity through their ability to break down bacterial cell walls, are likely to be particularly important for sperm defence as they are part of the constitutive innate immune system and are thus immediately available to protect sperm from bacterial attack. Birds are an ideal model for studies of ejaculate antimicrobial defences because of the dual function of the avian cloaca (i.e. waste excretion and sperm transfer), yet the antibacterial activity of avian ejaculates remains largely unexplored, and data on ejaculate lysozyme levels are only available for the domestic turkey (Meleagris gallopavo). Moreover, ejaculate lysozyme levels have not been reported for any species in the wild; which many argue is necessary to gain a comprehensive understanding of the function and dynamics of immune responses. Here, we show that lysozyme is present in the ejaculate of a wild passerine, the superb fairy‐wren (Malurus cyaneus), and that the concentration of lysozyme in ejaculates varies substantially among males. This variation, however, is not associated with male condition, sperm quality or plumage coloration. Nevertheless, we suggest that lysozyme‐associated antibacterial activity in ejaculates may be the target of natural and sexual selection and that these enzymes are likely to function in defending avian sperm from bacterial‐induced damage. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109 , 92–100.     

SARS‐CoV‐2 lgM/lgG antibody detection confirms the infection after three negative nucleic acid detection

An ongoing outbreak of viral pneumonia was caused by a novel coronavirus in China in 2019. By March 19, over 200 thousand confirmed cases of SARS‐CoV‐2 infection and over 9000 deaths have been reported throughout the world. For this infectious disease, nucleic acid detection is still the gold standard for pathogenic detection. However, nucleic acid detection takes a long time and has relatively high "false negative"; therefore, we need urgently a convenient and accurate detection method to make up for this deficiency. In this article, we will show such technical characteristics of lgM/lgG serum antibody detection, compared with nucleic acid detection.     

The immunology and ecology of co‐infection

It's a wormy world. All natural vertebrate populations are subject to infection and re‐infection with helminth parasites (Stoll 1947). Even in humans, around one billion people in developing nations are infected by one or several of a range of helminth parasites (Lustigman et al. 2012). Infection by worms is therefore the norm and is reflected in vertebrate immune responses. Thus, there is probably little point in generating an inflammatory response to clear every last worm, with ensuing collateral damage to our own tissue, when rapid re‐infection from the environment by another worm is pretty much assured. Instead, the vertebrate immune system modifies its response to worms, controlling (but not always clearing) these infections and at the same time limiting damage to host tissue caused by inflammatory immune responses (Jackson et al. 2009). The immune system, however, has to fight battles on several fronts and, while fighting a prolonged war of attrition against helminth parasites, it also has to protect against periodic invasion by bacteria, where a rapid response to kill invading microbes before they spread is essential (Fig.  1 ). In this issue of Molecular Ecology, Friberg et al. (2013) ask what effect worm infections have on a host's ability to mount antimicrobial responses.

Figure 1 Open in figure viewer PowerPoint Helminths generally produce chronic infections that elicit immune responses characterized by both the activation of T helper type 2 (Th2) cells and the production of regulatory responses, such as the cytokines transforming growth factor beta (TGF‐β) and interleukin‐10 (IL‐10) and regulatory T helper cells (T_REG). In combination, this immunological phenotype is often called a ‘modified’ Th2 response. Bacterial infections are recognized by pattern recognition receptors such as the Toll‐like receptors (TLRs) that are able to detect bacterial molecules such as lipopolysaccharides (by TLR‐4), flagellins (by TLR‐5) and unmethylated CpG (by TLR‐9) and generate a rapid inflammatory response [characterized by tumour necrosis factor (TNF)‐α production], particularly at the site of infection. As indicated by the dashed line, these contrasting responses have the potential to interact, especially in animals that spend much of their life harbouring chronic helminth infections that may have systemic anti‐inflammatory effects.

Friberg et al. ( 2013 ) begin their study in laboratory mice, where the immunological reagents exist to make mechanistic insights into helminth/bacterial co‐infections in a controlled environment. They focus on Toll‐like receptors (TLRs), which provide a first line of immune defence by recognizing microbial infection, triggering a rapid inflammatory response at the site of infection and can also help develop subsequent, acquired responses (Medzhitov 2001 ). Infection with the nematode Heligmosomoides polygyrus modified these responses but in a counter‐intuitive fashion. One might expect worm infection to reduce TLR‐mediated responses, consistent with a role of chronic helminth infections in down‐regulating inflammatory responses to limit tissue damage. Instead, TLR‐2, TLR‐4 and TLR‐9‐mediated cytokine responses tended to be elevated in worm infections, including that of tumour necrosis factor (TNF)‐α, which is a potent pro‐inflammatory cytokine. Potential explanations are that helminth infection changes the bacterial community composition of the gut flora or that helminth infection damages the gut wall and forces the host to defend itself against gut bacteria. Examining systemic effects of infection for immune responses within a whole animal (as opposed to cell culture) is challenging because immune responses are dynamic and variable. Having given an infective dose of nematodes, both the number of worms and the immune responses to these worms change through time. Friberg et al. ( 2013 ) also find that the dynamics of TLR‐mediated responses differ somewhat depending on the mouse strain used and on whether worm infections are delivered as a single pulse or split across multiple small doses (a so‐called ‘trickle’ infection), which may be more representation of infection in the field (Paterson et al. 2008 ). Varying the mode of infection and the host genetic background is important because the approach taken by much of the immunological literature is to try to eliminate variation by infecting a single host genotype with a single infective dose, which makes it difficult to generalize immunological results to the field. If examining immune responses in laboratory animals is difficult, what are the prospects for examining immune responses in a natural population? From a mechanistic perspective, the prospects would seem hopeless. The (already complex) dynamics of an immune response through time will be compounded by immunological variation among hosts in their pathogen exposure, age, nutrition and so forth that are found in natural populations. However, from an ecological perspective, quantifying the magnitude of variation in TLR‐mediated responses and identifying associations between immune responses and measurable variables such as macroparasite burden help to define what groups of individuals are most vulnerable to bacterial infection (Pedersen & Babayan 2011 ). Friberg et al. ( 2013 ) therefore performed an immuno‐epidemiological study on a natural population of wood mice (Apodemus sylvaticus) and found significant associations between H. polygyrus and ectoparasites on TLR2‐mediated TNF‐α production. The result, however, is a complex one in that the direction of the effect switched sharply between the 2 years in which the population was sampled. The cause of this switch is unclear, but may reflect qualitatively or quantitatively different pathogen exposures between the 2 years. Certainly, these data highlight that immune responses in the field are context‐dependent, even if the nature of that context remains elusive. Friberg et al.'s ( 2013 ) results, and a small but growing body of similar studies (Abolins et al. 2011 ; Boysen et al. 2011 ; Jackson et al. 2011 ), show both the potential and the difficulty in analysing immunological responses in the natural environment. In an earlier review in Molecular Ecology, Pedersen & Babayan ( 2011 ) make a compelling case to study the ecological context of immune responses in the wild. Ultimately, immune responses should enhance individual fitness, but it is not necessarily clear what constitutes a ‘good’ immune response. In particular, individuals in the wild may not have the luxury of deciding whether to tolerate a chronic worm infection or to clear an acute bacterial infection; the prevalence of co‐infection means that often they have to do both, often under conditions of nutritional stress (Pedersen & Babayan 2011 ). We are now only starting to bridge the gap between laboratory immunology and the ecology of natural populations. The technical barriers are readily apparent, including a lack of immunological reagents for non‐model species and the difficulty of sampling individuals and of measuring pathogen infection. Probably, a greater barrier, however, is linguistic; immunologists and ecologists speak very different languages. There is a steep learning curve for any ecologist trying to pick out what immune parameters they should try to measure in their system and how to interpret these. Equally, immunologists are unused to dealing with variation among individuals as anything other than a nuisance. However, there are great rewards for both ecologists and immunologists in understanding the sources of immunological variation in the field. It is therefore to be hoped that a common language can be developed between laboratory immunology and field ecology and that Molecular Ecology will be at the forefront of bringing these two fields together.

References

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S.P. wrote this article. S.P.‘s research focuses on the causes and consequences of genetic diversity in host and parasite populations. He is a director of the Centre for Genomic Research at the University of Liverpool and applies high‐throughput sequencing and gene expression methods to laboratory, domesticated and natural populations of animals and their pathogens.

Citing Literature

Number of times cited according to CrossRef: 1

• M Orsucci, M Navajas, S Fellous, Genotype-specific interactions between parasitic arthropods, Heredity, 10.1038/hdy.2016.90, 118 , 3, (260-265), (2016). Crossref

Volume 22 , Issue 10 May 2013

Pages 2603-2604     

A microtitre chemiluminescence sensor for detection of pyrethroids based on dual‐dummy‐template molecularly imprinted polymer and computational simulation

The residues of pyrethroids in foods of animal origin are dangerous to the consumers, so this study presented a chemiluminescence sensor for determination of pyrethroids in chicken samples. A dual‐dummy‐template molecularly imprinted polymer capable of recognizing 10 pyrethroids was synthesized. The results of computation simulation showed that the specific 3D conformations of the templates had important influences on the polymer' recognition ability. The polymer was used to prepare a sensor on conventional 96‐well microplates, and the sample solution was added into the wells for direct absorption. The absorbed analytes were initiated with the bis(2,4,6‐trichlorophenyl)oxalate–H₂O₂–imidazole system, and the chemiluminescence intensity was used for analyte quantification. Results showed that one assay was finished within 12 min, and this sensor could be reused four times. The limits of detection for the 10 analytes were in the range o0.3–6.0 pg/ml, and the recoveries from the standards of fortified blank chicken samples were in the range 70.5–99.7%.     

Enhancement of the antimicrobial properties of bacteriophage‐K via stabilization using oil‐in‐water nano‐emulsions

Bacteriophage therapy is a promising new treatment that may help overcome the threat posed by antibiotic‐resistant pathogenic bacteria, which are increasingly identified in hospitalized patients. The development of biocompatible and sustainable vehicles for incorporation of viable bacterial viruses into a wound dressing is a promising alternative. This article evaluates the antimicrobial efficacy of Bacteriophage K against Staphylococcus aureus over time, when stabilized and delivered via an oil‐in‐water nano‐emulsion. Nano‐emulsions were formulated via thermal phase inversion emulsification, and then bacterial growth was challenged with either native emulsion, or emulsion combined with Bacteriophage K. Bacteriophage infectivity, and the influence of storage time of the preparation, were assessed by turbidity measurements of bacterial samples. Newly prepared Bacteriophage K/nano‐emulsion formulations have greater antimicrobial activity than freely suspended bacteriophage. The phage‐loaded emulsions caused rapid and complete bacterial death of three different strains of S. aureus. The same effect was observed for preparations that were either stored at room temperature (18–20°C), or chilled at 4°C, for up to 10 days of storage. A response surface design of experiments was used to gain insight on the relative effects of the emulsion formulation on bacterial growth and phage lytic activity. More diluted emulsions had a less significant effect on bacterial growth, and diluted bacteriophage‐emulsion preparations yielded greater antibacterial activity. The enhancement of bacteriophage activity when delivered via nano‐emulsions is yet to be reported. This prompts further investigation into the use of these formulations for the development of novel anti‐microbial wound management strategies. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 30:932–944, 2014     

Interleukin‐17 family cytokines in protective immunity against infections: role of hematopoietic cell‐derived and non‐hematopoietic cell‐derived interleukin‐17s

Interleukin‐17 family cytokines, consisting of six members, participate in immune response in infections and autoimmune and inflammatory diseases. The prototype cytokine of the family, IL‐17A, was originally identified from CD4+ T cells which are now termed Th17 cells. Later, IL‐17A‐producing cells were expanded to include various hematopoietic cells, namely CD8+ T cells (Tc17), invariant NKT cells, γδ T cells, non‐T non‐B lymphocytes (termed type 3 innate lymphoid cells) and neutrophils. Some IL‐17 family cytokines other than IL‐17A are also expressed by CD4+ T cells: IL‐17E by Th2 cells and IL‐17F by Th17 cells. IL‐17A and IL‐17F induce expression of pro‐inflammatory cytokines to induce inflammation and anti‐microbial peptides to kill pathogens, whereas IL‐17E induces allergic inflammation. However, the functions of other IL‐17 family cytokines have been unclear. Recent studies have shown that IL‐17B and IL‐17C are expressed by epithelial rather than hematopoietic cells. Interestingly, expression of IL‐17E and IL‐17F by epithelial cells has also been reported and epithelial cell‐derived IL‐17 family cytokines shown to play important roles in immune responses to infections at epithelial sites. In this review, we summarize current information on hematopoietic cell‐derived IL‐17A and non‐hematopoietic cell‐derived IL‐17B, IL‐17C, IL‐17D, IL‐17E and IL‐17F in infections and propose functional differences between these two categories of IL‐17 family cytokines.     

Non‐viral gene delivery for cancer immunotherapy

Recent decades have witnessed the revolutionary development of cancer immunotherapies, which boost cancer‐specific immune responses for long‐term tumor regression. However, immunotherapy still has limitations, including off‐target side effects, long processing times and limited patient responses. These disadvantages of current immunotherapy are being addressed by improving our understanding of the immune system, as well as by establishing combinational approaches. Advanced biomaterials and gene delivery systems overcome some of these delivery issues, harnessing adverse effects and amplifying immunomodulatory effects, and are superior to standard formulations with respect to eliciting antitumor immunity. Nucleic acid‐based nanostructures have diverse functions, ranging from gene expression and gene regulation to pro‐inflammatory effects, as well as the ability to specifically bind different molecules. A brief overview is provided of the recent advances in the non‐viral gene delivery methods that are being used to activate cancer‐specific immune responses. Furthermore, the tumor microenvironment‐responsive synergistic strategies that modulate the immune response by targeting various signaling pathways are discussed. Nanoparticle‐based non‐viral gene delivery strategies have great potential to be implemented in the clinic for cancer immunotherapy.     

Long‐term infection of adult mice with murine polyomavirus following stereotaxic inoculation into the brain

Murine polyomavirus is used in various models of persistent virus infection. This study was undertaken to assess the spatial and temporal patterns of MPyV infection in the brains of immunocompetent (BALB/c) and immunocompromised (KSN nude) mice. MPyV was stereotaxically microinfused into the brain parenchyma, and the kinetics of infection were examined by quantitative PCR. In BALB/c mice, the amount of viral DNA in the brain peaked at 4 days p.i. and then rapidly diminished. In contrast, MPyV DNA levels increased up to 4 days and then gradually decreased over the 30‐day observation period in the brain of KSN mice. In both mouse strains, viral DNA was readily detected around the sites of inoculation from 2 to 6 days p.i., and continued to be detected for up to 30 days p.i. In addition, MPyV infection did not lead to a drastic induction of innate immune response in the brains, nor did MPyV‐inoculated mice show any signs of disease. These results indicate that MPyV establishes an asymptomatic long‐term infection in the mouse brain.