Influenza pandemics occur unpredictably when zoonotic influenza viruses with novel antigenicity acquire the ability to transmit amongst humans 1 . Incompatibilities between avian virus components and the human host limit host range breaches. Barriers include receptor preference, virion stability and poor activity of the avian virus RNA-dependent RNA polymerase in human cells 2 . Mutants of the heterotrimeric viral polymerase components, particularly PB2 protein, are selected during mammalian adaptation, but their mode of action is unknown [3][4][5][6] . We show that a species-specific difference in host protein ANP32A accounts for the suboptimal function of avian virus polymerase in mammalian cells. Avian ANP32A possesses an additional 33 amino acids between the LRR and LCAR domains. In mammalian cells, avian ANP32A rescued the suboptimal function of avian virus polymerase to levels similar to mammalian adapted polymerase. Deletion of the avian-specific sequence from chicken ANP32A abrogated this activity whereas its insertion into human ANP32A, or closely related ANP32B, supported avian virus polymerase function. Substitutions, such as PB2 E627K, rapidly selected upon infection of humans with avian H5N1 or H7N9 influenza viruses, adapt the viral polymerase for the shorter

Staphylococcus aureus is a major community and nosocomial pathogen. Its ability to withstand multiple stress conditions and quickly develop resistance to antibiotics complicates the control of staphylococcal infections. Adaptation to lower temperatures is a key for the survival of bacterial species outside the host. Branched-chain alpha-keto acid dehydrogenase (BKD) is an enzyme complex that catalyzes the early stages of branched-chain fatty acid (BCFA) production. In this study, BKD was inactivated, resulting in reduced levels of BCFAs in the membrane of S. aureus. Growth of the BKD-inactivated mutant was progressively more impaired than that of wild-type S. aureus with decreasing temperature, to the point that the mutant could not grow at 12 degrees C. The growth of the mutant was markedly stimulated by the inclusion of 2-methylbutyrate in the growth medium at all temperatures tested. 2-Methylbutyrate is a precursor of odd-numbered anteiso fatty acids and bypasses BKD. Interestingly, growth of wild-type S. aureus was also stimulated by including 2-methylbutyrate in the medium, especially at lower temperatures. The anteiso fatty acid content of the BKD-inactivated mutant was restored by the inclusion of 2-methylbutyrate in the medium. Fluorescence polarization measurements indicated that the membrane of the BKD-inactivated mutant was significantly less fluid than that of wild-type S. aureus. Consistent with this result, the mutant showed decreased toluene tolerance that could be increased by the inclusion of 2-methylbutyrate in the medium. The BKD-inactivated mutant was more susceptible to alkaline pH and oxidative stress conditions. Inactivation of the BKD enzyme complex in S. aureus also led to a reduction in adherence of the mutant to eukaryotic cells and its survival in a mouse host. In addition, the mutant offers a tool to study the role of membrane fluidity in the interaction of S. aureus with antimicrobial substances.

In alkaline conditions, Listeria monocytogenes cells develop higher proportions of branched-chain fatty acids (FAs), including more anteiso forms. In acid conditions, the opposite occurs. Reduced growth of pH-sensitive mutants at adverse pH (5.0/9.0) was alleviated by the addition of 2-methylbutyrate (an anteiso-FA precursor), suggesting that anteiso-FAs are important in adaptation to adverse pH. The balance between anteiso-and iso-FAs may be more important than changes in the amounts and/or degrees of saturation of FAs in pH adaptation.Listeria monocytogenes can grow under a wide range of pH stress, i.e., 4.1 to 9.0 (38, 46), increasing its abilities to persist during food processing and attempts to decontaminate food-processing environments (15,(42)(43)(44)(45). It also has particularly impressive capacities to modulate its membrane lipids to maintain membrane fluidity and transport functions (10,40,41) in response to temperature (1), salt (7), and CO 2 /anaerobiotic (21) stress. Such capacities have been suggested to be related to its atypically high iso and anteiso, odd-numbered, branched-chain fatty acid (BCFA) content (1,20) and its ability to modulate the overall content and proportions of BCFAs, straight-chain FAs (SCFAs), and unsaturated FAs (22,23). For example, reductions in environmental temperatures lead to increases in the amount of ai15:0 present in L. monocytogenes cell membranes, while increases in environmental temperatures lead to reductions in the amounts of ai15:0 and other BCFAs present in membranes (1,14,32).Changes in FA profile have been associated with pH adaptation in Streptococcus mutans (16-18), Escherichia coli (5, 48), and Salmonella (24), Pseudomonas (31), and Bacillus species (23). However, little is known about pH stress-associated modulation of FAs in L. monocytogenes (21), the wider role of FA modulation in its responses to nonthermal stresses, or the cross-protection mechanisms which operate in this hardy pathogen (19,27,35,44).The aims of this study were to investigate the modulation of the FA profile of L. monocytogenes membranes in response to changes in environmental pH, investigate the effects of an exogenous BCFA precursor on the pH stress response of BCFA-deficient mutants (1, 49), and examine possible links between the prevalence of anteiso-BCFAs and the adaptation mechanism(s) of L. monocytogenes under adverse pH conditions. Modified brain heart infusion broth (MBHIB; Difco Laboratories, Sparks, MD), suitable for adverse-pH studies, was prepared to pH 5.0, 5.5, and 6.0 in 2 M disodium phosphate Washed cells from mid-exponential-phase cultures of L. monocytogenes 10403S, an isogenic sigB null mutant (3), and isogenic non-BCFA-producing cld-1 and cld-2 mutants (1, 49) were inoculated into preheated (30°C) 100-ml volumes of the buffered MBHIB and grown (30°C/200 rpm) to an optical density at 600 nm of 0.5 to 0.6. Growth rates of cultures (doubling times per hour of cultures in exponential growth) were calculated (2). Mid-exponential-phase cells were recovered by centrif...

SARS-CoV-2 attacks various organs, most destructively the lung, and cellular entry requires two host cell surface proteins: ACE2 and TMPRSS2. Downregulation of one or both of these is thus a potential therapeutic approach for COVID-19. TMPRSS2 is a known target of the androgen receptor, a ligand-activated transcription factor; androgen receptor activation increases TMPRSS2 levels in various tissues, most notably prostate. We show here that treatment with the antiandrogen enzalutamide—a well-tolerated drug widely used in advanced prostate cancer—reduces TMPRSS2 levels in human lung cells and in mouse lung. Importantly, antiandrogens significantly reduced SARS-CoV-2 entry and infection in lung cells. In support of this experimental data, analysis of existing datasets shows striking co-expression of AR and TMPRSS2, including in specific lung cell types targeted by SARS-CoV-2. Together, the data presented provides strong evidence to support clinical trials to assess the efficacy of antiandrogens as a treatment option for COVID-19.

Evidence of an association between added sugars (AS) and the risk of obesity has triggered public health bodies to develop strategies enabling consumers to manage their AS intake. The World Health Organisation (WHO) has strongly recommended a reduction of free sugars to 10% of total dietary energy (TE) and conditionally recommended a reduction to 5% TE to achieve health benefits. Despite food labelling being a policy tool of choice in many countries, there is no consensus on the mandatory addition of AS to the nutrition panel of food labels. An online survey was conducted to explore consumer ability to identify AS on food labels and to investigate consumer awareness of the WHO guidelines in relation to sugar intakes. The questionnaire was tested for participant comprehension using face-to-face interviews prior to conducting the online study. The online survey was conducted in Northern Ireland during May 2015 and was completed by a convenient sample of 445 subjects. Results showed that just 4% of respondents correctly classified 10 or more ingredients from a presented list of 13 items, while 65% of participants were unaware of the WHO guidelines for sugar intake. It may be timely to reopen dialogue on inclusion of AS on food product nutrition panels.

BackgroundMicrobiological standards within pork slaughter processing plants in the European Union are currently governed by Commission Regulation (EC) 2073/2005, which describes detailed performance criteria at specific stages of the procedure (following carcass dressing and before chilling) for total viable counts (TVC), Enterobacteriaceae (EB) and Salmonella spp. In this study, 95 carcasses from an Irish pork slaughter plant were sampled by swabbing 100 cm2 of surface at three sites (belly, ham, jowl) to examine the effects of eight processing stages (stunning, bleeding, scalding, singeing, polishing, evisceration, final inspection and chilling) on contamination levels.ResultsTVC ranged from approximately 1.7–6.3 log cfu cm2 during sampling. There were significant reductions in TVC for all sites after scalding and singeing (p < 0.05), whilst there was a significant increase in counts after polishing and evisceration (p < 0.05) compared with preceding stages. EB counts indicated hygienic weak points in the examined slaughter plant leading to faecal (cross)-contamination, with elevated counts after stunning, bleeding and evisceration (p < 0.05), compared with final counts after chilling.ConclusionsAlthough the bacterial numbers reported in this study may reflect specific plant practices and temporal influences, results show that contamination can be introduced at various steps in the process and highlight the importance of monitoring locations other than those required by legislation within the process. Monitoring can be used to establish baseline levels for high-risk stages specific to each plant and to assess the effectiveness of additional interventions.

Viruses that infect birds pose major threats—to the global supply of chicken, the major, universally-acceptable meat, and as zoonotic agents (e.g. avian influenza viruses H5N1 and H7N9). Controlling these viruses in birds as well as understanding their emergence into, and transmission amongst, humans will require considerable ingenuity and understanding of how different species defend themselves. The type I interferon-coordinated response constitutes the major antiviral innate defence. Although interferon was discovered in chicken cells, details of the response, particularly the identity of hundreds of stimulated genes, are far better described in mammals. Viruses induce interferon-stimulated genes but they also regulate the expression of many hundreds of cellular metabolic and structural genes to facilitate their replication. This study focusses on the potentially anti-viral genes by identifying those induced just by interferon in primary chick embryo fibroblasts. Three transcriptomic technologies were exploited: RNA-seq, a classical 3′-biased chicken microarray and a high density, “sense target”, whole transcriptome chicken microarray, with each recognising 120–150 regulated genes (curated for duplication and incorrect assignment of some microarray probesets). Overall, the results are considered robust because 128 of the compiled, curated list of 193 regulated genes were detected by two, or more, of the technologies.Electronic supplementary materialThe online version of this article (doi:10.1186/s13567-016-0363-8) contains supplementary material, which is available to authorized users.

Fowlpox virus is the type species of an extensive and poorly-defined group of viruses isolated from more than 200 species of birds, together comprising the avipoxvirus genus of the poxvirus family. Long known as a significant poultry pathogen, vaccines developed in the early and middle years of the twentieth century led to its effective eradication as a problem to commercial production in temperate climes in developed western countries (such that vaccination there is now far less common). Transmitted mechanically by biting insects, it remains problematic, causing significant losses to all forms of production (from backyard, through extensive to intensive commercial flocks), in tropical climes where control of biting insects is difficult. In these regions, vaccination (via intradermal or subcutaneous, and increasingly in ovo, routes) remains necessary. Although there is no evidence that more than a single serotype exists, there are poorly-described reports of outbreaks in vaccinated flocks. Whether this is due to inadequate vaccination or penetrance of novel variants remains unclear. Some such outbreaks have been associated with strains carrying endogenous, infectious proviral copies of the retrovirus reticuloendotheliosis virus (REV), which might represent a pathotypic (if not newly emerging) variant in the field. Until more is known about the phylogenetic structure of the avipoxvirus genus (by more widespread genome sequencing of isolates from different species of birds) it remains difficult to ascertain the risk of novel avipoxviruses emerging from wild birds (and/or by recombination/mutation) to infect farmed poultry.