Yamada, K. J., Heim, C. E., Aldrich, A. L., Gries, C. M., Staudacher, A. G., Kielian, T.

S. aureus is a leading cause of device-associated biofilm infections, which represent a serious health care concern based on their chronicity and antibiotic resistance. We previously reported that S. aureus biofilms preferentially recruit myeloid-derived suppressor cells (MDSCs), which promote monocyte and macrophage anti-inflammatory properties. This is associated with increased myeloid arginase-1 (Arg-1) expression, which has been linked to anti-inflammatory and pro-fibrotic activity that are observed during S. aureus biofilm infections. To determine whether MDSCs and macrophages utilize Arg-1 to promote biofilm infection, Arg-1 was deleted in myeloid cells using Tie-2Cre mice. Despite Arg-1 expression in biofilm-associated myeloid cells, bacterial burdens and leukocyte infiltrates were similar between wild type (WT) and Arg-1fl/fl;Tie-2Cre conditional knockout (KO) mice from days 3 to 14 post-infection in both orthopedic implant and catheter-associated biofilm models. However, inducible nitric oxide synthase (iNOS) expression was dramatically elevated in biofilm-associated MDSCs from Arg-1fl/fl;Tie-2Cre animals, suggesting a potential Arg-1-independent compensatory mechanism for MDSC-mediated immunomodulation. Treatment of Arg-1fl/fl;Tie-2Cre mice with the iNOS inhibitor N6-(1-Iminoethyl)-lysine, hydrochloride (L-NIL) had no effect on biofilm burdens or immune infiltrates, whereas treatment of WT mice with the Arg-1/ornithine decarboxylase inhibitor difluoromethylornithine (DFMO) increased bacterial titers, but only in the surrounding soft tissues that possess planktonic attributes. A role for myeloid-derived Arg-1 in regulating planktonic infection was confirmed using a subcutaneous abscess model, where S. aureus burdens were significantly increased in Arg-1fl/fl;Tie-2Cre compared to WT mice. Collectively, these results indicate that the effects of myeloid Arg-1 are context-dependent and are manifest during planktonic, but not biofilm infection.

Liu, L. R., Hood, J. D., Yu, Y., Zhang, J. T., Hutzler, N. R., Rosenband, T., Ni, K.- K.

Chemical reactions typically proceed via stochastic encounters between reactants. Going beyond this paradigm, we combine exactly two atoms into a single, controlled reaction. The experimental apparatus traps two individual laser-cooled atoms (one sodium and one cesium) in separate optical tweezers and then merges them into one optical dipole trap. Subsequently, photo-association forms an excited-state NaCs molecule. The discovery of previously unseen resonances near the molecular dissociation threshold and measurement of collision rates are enabled by the tightly trapped ultracold sample of atoms. As laser-cooling and trapping capabilities are extended to more elements, the technique will enable the study of more diverse, and eventually more complex, molecules in an isolated environment, as well as synthesis of designer molecules for qubits.

Abstract Background Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne disease. Haemophysalis longicornis ticks have been considered the vector of severe fever with thrombocytopenia syndrome virus (SFTSV). However, clear data on the transmission of SFTS from ticks to humans are limited. Case presentation We report an 84-year-old woman who presented with fever and altered mentality, which was confirmed as SFTS with encephalopathy by reverse-transcription polymerase chain reaction in blood and cerebrospinal fluid. The SFTSV was also identified in the tick that bit her, H. longicornis. Phylogenetic analyses indicated that the SFTSV from the patient and the tick was identical. The patient gradually recovered with treatments of corticosteroids and immunoglobulin. Conclusion These findings provide further evidence of SFTS viral transmission from H. longicornis to human.

Morrison, S. G., Giebel, A. M., Toh, E. C., Spencer, H. J., Nelson, D. E., Morrison, R. P.

Some members of the genus Chlamydia, including the human pathogen Chlamydia trachomatis, infect multiple tissues including the genital and gastrointestinal (GI) tracts. However, it is unknown if bacterial targeting to these sites is mediated by multifunctional or distinct chlamydial factors. We previously showed that disruption of individual large clostridial toxin homologs encoded within the Chlamydia muridarum plasticity zone were not critical for murine genital tract infection. Here, we assessed if cytotoxin genes contribute to C. muridarum GI tropism. Infectivity and shedding of wild-type (WT) C. muridarum and three mutants containing nonsense mutations in different cytotoxin genes, tc0437, tc0438, and tc0439, were compared in mouse genital and GI infection models. One mutant, that had a nonsense mutation in tc0439, was highly attenuated for GI infection and had a GI ID50 that was 1000 times greater than WT. GI inoculation with this mutant failed to elicit anti-chlamydial antibodies or to protect against subsequent genital tract infection. Genome sequencing of the tc0439 mutant revealed additional chromosomal mutations, and phenotyping of additional mutants suggested that the GI attenuation might be linked to a nonsense mutation in tc0600. The molecular mechanism underlying this dramatic difference in tissue-tropic virulence is not fully understood. However, isolation of these mutants demonstrates that distinct chlamydial chromosomal factors mediate chlamydial tissue tropism, and provides a basis for vaccine initiatives to isolate chlamydia strains that are attenuated for genital infection, but retain the ability to colonize the GI tract and elicit protective immune responses.

Abstract Background Nosocomial, or healthcare-associated infections (HAI), exact a high medical and financial toll on patients, healthcare workers, caretakers, and the health system. Interpersonal contact patterns play a large role in infectious disease spread, but little is known about the relationship between health care workers’ (HCW) movements and contact patterns within a heath care facility and HAI. Quantitatively capturing these patterns will aid in understanding the dynamics of HAI and may lead to more targeted and effective control strategies in the hospital setting. Methods Staff at 3 urban university-based tertiary care hospitals in Canada completed a detailed questionnaire on demographics, interpersonal contacts, in-hospital movement, and infection prevention and control practices. Staff were divided into categories of administrative/support, nurses, physicians, and “Other HCWs” - a fourth distinct category, which excludes physicians and nurses. Using quantitative network modeling tools, we constructed the resulting HCW “co-location network” to illustrate contacts among different occupations and with locations in hospital settings. Results Among 3048 respondents (response rate 38%) an average of 3.79, 3.69 and 3.88 floors were visited by each HCW each week in the 3 hospitals, with a standard deviation of 2.63, 1.74 and 2.08, respectively. Physicians reported the highest rate of direct patient contacts (> 20 patients/day) but the lowest rate of contacts with other HCWs; nurses had the most extended (> 20 min) periods of direct patient contact. “Other HCWs” had the most direct daily contact with all other HCWs. Physicians also reported significantly more locations visited per week than nurses, other HCW, or administrators; nurses visited the fewest. Public spaces such as the cafeteria had the most staff visits per week, but the least mean hours spent per visit. Inpatient settings had significantly more HCW interactions per week than outpatient settings. Conclusions HCW contact patterns and spatial movement demonstrate significant heterogeneity by occupation. Control strategies that address this diversity among health care workers may be more effective than “one-strategy-fits-all” HAI prevention and control programs.

NMN NikNadia , Chee Wah Tan , Kien Chai Ong , I‐Ching Sam , Yoke Fun Chan

Abstract Background Despite universal prophylaxis, late cytomegalovirus (CMV) infection occurs in a high proportion of kidney transplant recipients. We evaluated whether a specific viral T-cell response allows for the better identification of recipients who are at high risk of CMV infection after prophylaxis withdrawal. Methods We conducted a prospective study in 19 pretransplant anti-CMV seronegative kidney graft recipients R- (18 from seropositive donors [D+] and one from a seronegative donor [D-]) and 67 seropositive recipients R(+) (59 from seropositive donors and eight from seronegative donors) who received antiviral prophylaxis with valganciclovir. The QuantiFERON-CMV (QF-CMV) assay was performed within the first and third months after transplantation. Blood samples were monitored for CMV DNAemia using a commercial quantitative nucleic acid amplification test (QNAT) that was calibrated to the World Health Organization International Standard. Results Twenty-one of the 86 patients (24%) developed CMV viremia after prophylaxis withdrawal within 12 months posttransplantation. In the CMV R(+) group, the QF-CMV assay yielded reactive results (QF-CMV[+]) in 51 of 67 patients (76%) compared with 7 of 19 patients (37%) in the CMV R(−) group (p = 0.001). In the CMV R(+) group, infection occurred in seven of 16 recipients (44%) who were QF-CMV(−) and eight of 51 recipients (16%) who were QF-CMV(+). In the CMV R(−) group, infection evolved in five of 12 recipients (42%) who were QF-CMV(−) and one of 7 recipients (14%) who were QF-CMV(+). No difference was found in the incidence of CMV infection stratified according to the QF-CMV results with regard to the recipients’ pretransplant CMV IgG serology (p = 0.985). Cytomegalovirus infection occurred in 15 of 36 patients (42%) with hypogammaglobulinemia (HGG) 90 days posttransplantation compared with two of 34 patients (6%) without HGG (p = 0.0004). Cytomegalovirus infection occurred in seven of 13 patients (54%) with lymphocytopenia compared with 14 of 70 patients (20%) without lymphocytopenia (p = 0.015). The multivariate analysis revealed that the nonreactive QuantiFERON-CMV assay was an independent risk factor for postprophylaxis CMV infection. Conclusions In kidney transplant recipients who received posttransplantation prophylaxis, negative QF-CMV results better defined the risk of CMV infection than initial CMV IgG status after prophylaxis withdrawal. Hypogammaglobulinemia and lymphocytopenia were risk factors for CMV infection.

Voelker R.

The FDA has warned 3 duodenoscope manufacturers that they’ve failed to comply with a federal requirement to assess whether current cleaning and disinfecting methods effectively reduce infection risk.

Abstract Background Despite vancomycin use is a major risk factor for the emergence of vancomycin resistance, it is frequently inappropriately prescribed, especially as empirical treatment. We evaluated the effect of an antimicrobial stewardship intervention targeting for inappropriate continued empirical vancomycin use. Methods This was a quasi-experimental study comparing vancomycin use in a 6-month pre-intervention and 6-month intervention period. If empirical vancomycin was continued for more than 96 h without documentation of beta-lactam-resistant gram-positive microorganisms, it was considered inappropriate continued empirical vancomycin use. The intervention consisted of the monitoring of appropriateness by a pharmacist and direct discussion with the prescribing physicians by infectious disease specialists when empirical vancomycin was continued inappropriately. An interrupted time series analysis was used to compare vancomycin use before and during the intervention. Results Following implementation of the intervention, overall vancomycin consumption decreased by 14.6%, from 37.6 defined daily doses (DDDs)/1000 patient-days in the pre-intervention period to 32.1 DDDs/1000 patient-days in the intervention period (P …

Ghadimi, A. H., Fedorov, S. A., Engelsen, N. J., Bereyhi, M. J., Schilling, R., Wilson, D. J., Kippenberg, T. J.

Extreme stresses can be produced in nanoscale structures, a feature which has been used to realize enhanced materials properties, such as the high mobility of silicon in modern transistors. Here we show how nanoscale stress can be used to realize exceptionally low mechanical dissipation, when combined with "soft-clamping" — a form of phononic engineering. Specifically, using a non-uniform phononic crystal pattern, we colocalize the strain and flexural motion of a free-standing Si3N4 nanobeam. Ringdown measurements at room temperature reveal string-like modes with quality (Q) factors as high as 800 million and Q x frequency exceeding 1015 Hz. These results illustrate a promising route for engineering ultra-coherent nanomechanical devices.

Abstract Background Alterations in inflammatory cytokines and genetic background of the host contribute to the outcome of malaria infection. Despite the promising protective role of IL-17 in infections, little attention is given to further understand its importance in the pathogenesis of severe malaria anaemia in chronic/endemic situations. The objective of this study, therefore, was to evaluate IL-17 levels in anaemic condition and its association with host genetic factors. Methods Two mice strains (Balb/c and CBA) were crossed to get the F1 progeny, and were (F1, Balb/c, CBA) taken through 6 cycles of Plasmodium berghei (ANKA strain) infection and chloroquine/pyrimethamine treatment to generate semi-immune status. Cytokine levels and kinetics of antibody production, CD4+CD25+T regulatory cells were evaluated by bead-based multiplex assay kit, ELISA and FACs, respectively. Results High survival with high Hb loss at significantly low parasitaemia was observed in Balb/c and F1. Furthermore, IgG levels were two times higher in Balb/c, F1 than CBA. While CD4+CD25+ Treg cells were lower in CBA; IL-4, IFN-γ, IL-12α and IL-17 were significantly higher (p …

Abstract Background A yellow fever epidemic occurred in Angola in 2016 with 884 laboratory confirmed cases and 373 deaths. Eleven unvaccinated Chinese nationals working in Angola were also infected and imported the disease to China, thereby presenting the first importation of yellow fever into Asia. In Angola, there are about 259,000 Chinese foreign workers. The fact that 11 unvaccinated Chinese workers acquired yellow fever suggests that many more Chinese workers in Angola were not vaccinated. Methods We applied a previously developed model to back-calculate the number of unvaccinated Chinese workers in Angola in order to determine the extent of lack of vaccine coverage. Results Our models suggest that none of the 259,000 Chinese had been vaccinated, although yellow fever vaccination is mandated by the International Health Regulations. Conclusion Governments around the world including China need to ensure that their citizens obtain YF vaccination when traveling to countries where such vaccines are required in order to prevent the international spread of yellow fever.

Srivastava, A. P., Luo, M., Zhou, W., Symersky, J., Bai, D., Chambers, M. G., Faraldo-Gomez, J. D., Liao, M., Mueller, D. M.

Mitochondrial ATP synthase comprises a membrane embedded Fo motor that rotates to drive ATP synthesis in the F1 subunit. We used single-particle cryo-EM to obtain structures of the full complex in a lipid bilayer in the absence or presence of the inhibitor oligomycin, at 3.6 Å and 3.8 Å resolution, respectively. To limit conformational heterogeneity, we locked the rotor in a single conformation by fusing the F6 subunit of the stator with the -subunit of the rotor. Assembly of the enzyme with the F6- fusion caused a twisting of the rotor and a 9° rotation of the Fo c10-ring in the direction of ATP synthesis, relative to the structure of isolated Fo. Our cryo-EM structures show how F1 and Fo are coupled, give insight into the proton translocation pathway and show how oligomycin blocks ATP synthesis.

Stylianou, E., Harrington-Kandt, R., Beglov, J., Bull, N., Pinpathomrat, N., Swarbrick, G. M., Lewinsohn, D. A., Lewinsohn, D. M., McShane, H.

The development of a vaccine against tuberculosis (TB), a disease caused by Mycobacterium tuberculosis (M.tb), is urgently needed. The only currently available vaccine, BCG, has variable efficacy. One approach in the global vaccine development effort is focused on boosting BCG using subunit vaccines. The identification of novel antigens for inclusion in subunit vaccines is a critical step in the TB vaccine development pathway. We selected four novel mycobacterial antigens recognised during the course of human infection. A replication deficient chimpanzee adenovirus (ChAdOx1) was constructed to express each antigen individually and these vectors were evaluated for protective efficacy in murine M.tb challenge experiments. One antigen, PPE15 (Rv1039c), conferred significant and reproducible protection when administered alone and as a boost to BCG vaccination. We identified immunodominant epitopes to define the protective immune responses using tetramers and intravascular staining. Lung parenchymal CD4+ and CD8+ CXCR3+ KLRG1- T cells, previously associated with M.tb protection, were enriched in vaccinated compared to control groups. Further work to evaluate the protective efficacy of PPE15 in more stringent preclinical animal models is now merited, together with the identification of further novel protective antigens using this selection strategy.

Ravinder Singh , Aparna Mukherjee , Mohit Singla , Madhu Vajpayee , Neema Negi , Sushil K. Kabra , Rakesh Lodha , Bimal K. Das

B‐cells play an important role in defending children against various infections. In view of scare data, we undertook this prospective cohort study to describe B cell compartment in HIV infected children (…

Barthelemy, A., Sencio, V., Soulard, D., Deruyter, L., Faveeuw, C., Le Goffic, R., Trottein, F.

Severe bacterial (pneumococcal) infections are commonly associated with influenza and are significant contributors to the excess morbidity and mortality of influenza. Disruption of lung tissue integrity during influenza participates in bacterial pulmonary colonization and dissemination out of the lungs. Interleukin (IL)-22 has gained considerable interest in anti-inflammatory and anti-infection immunotherapy over the last decade. In the current study, we investigated the effect of exogenous IL-22 delivery on the outcome of pneumococcal superinfection post-influenza. Our data show that exogenous treatment of influenza-infected mice with recombinant IL-22 reduces bacterial dissemination out of the lungs but is without effect on pulmonary bacterial burden. Reduced systemic bacterial dissemination was linked to reinforced pulmonary barrier functions, as revealed by total protein measurement in the bronchoalveolar fluids, intratracheal fluorescein isothiocyanate-dextran tracking and histological approaches. We describe an IL-22 specific gene signature in the lung tissue of IAV-infected (and naïve) mice that might explain the observed effects. Indeed, exogenous IL-22 modulates gene expression profile in a way suggesting a reinforcement of tissue integrity. Our results open the way to alternative approaches for limiting post-influenza bacterial superinfection, particularly systemic bacterial invasion.

K. Sabapathy , C. Mulubwa , H. Mathema , C. Mubekapi‐Musadaidzwa , A. Schaap , G. Hoddinott , J. Hargreaves , S. Floyd , H. Ayles, R. Hayes , for

Abstract Objective The HPTN 071 (PopART) trial is examining the impact of a package including universal testing and treatment on community‐level HIV incidence in Zambia and South Africa. We conducted a nested case–control study to examine factors associated with acceptance of home‐based HIV testing and counselling (HB‐HTC) delivered by community HIV‐care providers (CHiPs) in PopART intervention communities. Methods Of 295 447 individuals who were offered testing, random samples of individuals who declined HB‐HTC (cases) and accepted HB‐HTC (controls), stratified by gender and community, were selected. Odds ratios comparing cases and controls were estimated using multivariable logistic regression. Results Data from 642 participants (313 cases, 329 controls) were analysed. There were no differences between cases and controls by demographic or behavioural characteristics including age, marital or socio‐economic position. Participants who felt they could be open with CHiPs (AOR: 0.46, 95% CI: 0.30–0.71, P < 0.001); self‐reported as not previously tested (AOR: 0.64; 95% CI: 0.43–0.95, P = 0.03); considered HTC at home to be convenient (AOR: 0.38, 95% CI: 0.27–0.54, P = 0.001); knowing others who had accepted HB‐HTC from the CHiPs (AOR: 0.49, 95% CI: 0.31–0.77, P = 0.002); or were motivated to get treatment without delay (AOR: 0.60, 95% CI: 0.43–0.85, P = 0.004) were less likely to decline the offer of HB‐HCT. Those who self‐reported high‐risk sexual behaviour were also less likely to decline HB‐HCT (AOR: 0.61, 95% CI: 0.39–0.93, P = 0.02). Having stigmatising attitudes about HB‐HTC was not an important barrier to HB‐HCT uptake. Men who reported fear of HIV were more likely to decline HB‐HCT (AOR: 2.68, 95% CI: 1.33–5.38, P = 0.005). Conclusion Acceptance of HB‐HTC was associated with lack of previous HIV testing, positive attitudes about HIV services/treatment and perception of high sexual risk. Uptake of HB‐HCT among those offered it was similar across a range of demographic and behavioural subgroups suggesting it was ‘universally’ acceptable.

Abstract Background Several studies have applied ecological factors such as meteorological variables to develop models and accurately predict the temporal pattern of dengue incidence or occurrence. With the vast amount of studies that investigated this premise, the modeling approaches differ from each study and only use a single statistical technique. It raises the question of whether which technique would be robust and reliable. Hence, our study aims to compare the predictive accuracy of the temporal pattern of Dengue incidence in Metropolitan Manila as influenced by meteorological factors from four modeling techniques, (a) General Additive Modeling, (b) Seasonal Autoregressive Integrated Moving Average with exogenous variables (c) Random Forest and (d) Gradient Boosting. Methods Dengue incidence and meteorological data (flood, precipitation, temperature, southern oscillation index, relative humidity, wind speed and direction) of Metropolitan Manila from January 1, 2009 – December 31, 2013 were obtained from respective government agencies. Two types of datasets were used in the analysis; observed meteorological factors (MF) and its corresponding delayed or lagged effect (LG). After which, these datasets were subjected to the four modeling techniques. The predictive accuracy and variable importance of each modeling technique were calculated and evaluated. Results Among the statistical modeling techniques, Random Forest showed the best predictive accuracy. Moreover, the delayed or lag effects of the meteorological variables was shown to be the best dataset to use for such purpose. Thus, the model of Random Forest with delayed meteorological effects (RF-LG) was deemed the best among all assessed models. Relative humidity was shown to be the top-most important meteorological factor in the best model. Conclusion The study exhibited that there are indeed different predictive outcomes generated from each statistical modeling technique and it further revealed that the Random forest model with delayed meteorological effects to be the best in predicting the temporal pattern of Dengue incidence in Metropolitan Manila. It is also noteworthy that the study also identified relative humidity as an important meteorological factor along with rainfall and temperature that can influence this temporal pattern.

Langdon, E. M., Qiu, Y., Ghanbari Niaki, A., McLaughlin, G. A., Weidmann, C., Gerbich, T. M., Smith, J. A., Crutchley, J. M., Termini, C. M., Weeks, K. M., Myong, S., Gladfelter, A. S.

RNA promotes liquid-liquid phase separation (LLPS) to build membraneless compartments in cells. How distinct molecular compositions are established and maintained in these liquid compartments is unknown. Here, we report that secondary structure allows mRNAs to self-associate and determines whether an mRNA is recruited to or excluded from liquid compartments. The polyQ-protein Whi3 induces conformational changes in RNA structure and generates distinct molecular fluctuations depending on the RNA sequence. These data support a model in which structure-based, RNA-RNA interactions promote assembly of distinct droplets and protein-driven, conformational dynamics of the RNA maintain this identity. Thus, the shape of RNA can promote the formation and coexistence of the diverse array of RNA-rich liquid compartments found in a single cell.

Voelker R.

Combination antiretroviral (AR) therapy has allowed most—but not all—people with HIV to manage their infection as a chronic disease. But for those with multidrug-resistant (MDR) HIV-1 that hasn’t responded to multiple treatment regimens, the FDA has approved a new treatment.

Abstract Background The use of new types of drugs has become more common among men who have sex with men (MSM). The aim of this study was to describe the patterns of the use of new types of drugs, such as methamphetamine, ketamine, ecstasy, and rush poppers, and to examine the factors associated with drug use and HIV infection among MSM in Hangzhou, China. Methods This cross-sectional study was conducted between August 2015 and April 2016. We used snowball sampling to recruit MSM; participants were recruited from voluntary counseling and testing centers, baths, bars, Blued (an app for the gay community), QQ groups, clubs, and other types of venues. MSM were included if their previous HIV test results were negative or unknown, or they had not been tested for HIV. MSM were excluded if they were known to be HIV positive before the survey. Face-to-face questionnaires were conducted and a venous blood specimen was drawn from each participant following the interview. Results In total, 555 MSM were included; 18.2% (101/555) of the participants had used new types of drugs in the past 3 months. Among the users, 65.3% used single-use rush poppers, while the remainder used ketamine, methamphetamine, ecstasy, or other mixed combinations of drugs. The HIV positivity rate was 14.8% (82/555). Factors associated with increased odds of using new types of drugs in the past 3 months were higher education levels (adjusted odds ratio [AOR] 4.45, 95% confidence interval [CI] 2.12–9.37), having multiple sexual partners (AOR 1.76, 95 CI 1.02–3.05), alcohol use before sexual intercourse (AOR 33.44, 95% CI 10.80–103.50), and seeing friends using new types of drugs. Conclusion We revealed the widespread use of new types of drugs, as well as a high diagnosis rate of new HIV infection, among MSM in Hangzhou. The use of new types of drugs was associated with an increased number of sexual partners among MSM; the high-risk sexual behaviors increased the risk of HIV infection. Attention should be given to the use of new types of drugs in MSM, and supervision programs should be strengthened to combat drug use.

Abstract Background In malaria endemic populations, complex patterns of Plasmodium vivax and Plasmodium falciparum blood-stage infection dynamics may be observed. Genotyping samples from longitudinal cohort studies for merozoite surface protein (msp) variants increases the information available in the data, allowing multiple infecting parasite clones in a single individual to be identified. msp genotyped samples from two longitudinal cohorts in Papua New Guinea (PNG) and Thailand were analysed using a statistical model where the times of acquisition and clearance of each clone in every individual were estimated using a process of data augmentation. Results For the populations analysed, the duration of blood-stage P. falciparum infection was estimated as 36 (95% Credible Interval (CrI): 29, 44) days in PNG, and 135 (95% CrI 94, 191) days in Thailand. Experiments on simulated data indicated that it was not possible to accurately estimate the duration of blood-stage P. vivax infections due to the lack of identifiability between a single blood-stage infection and multiple, sequential blood-stage infections caused by relapses. Despite this limitation, the method and data point towards short duration of blood-stage P. vivax infection with a lower bound of 24 days in PNG, and 29 days in Thailand. On an individual level, P. vivax recurrences cannot be definitively classified into re-infections, recrudescences or relapses, but a probabilistic relapse phenotype can be assigned to each P. vivax sample, allowing investigation of the association between epidemiological covariates and the incidence of relapses. Conclusion The statistical model developed here provides a useful new tool for in-depth analysis of malaria data from longitudinal cohort studies, and future application to data sets with multi-locus genotyping will allow more detailed investigation of infection dynamics.

Maharana, S., Wang, J., Papadopoulos, D. K., Richter, D., Pozniakovsky, A., Poser, I., Bickle, M., Rizk, S., Guillen-Boixet, J., Franzmann, T., Jahnel, M., Marrone, L., Chang, Y.-T., Sterneckert, J., Tomancak, P., Hyman, A. A., Alberti, S.

Prion-like RNA binding proteins (RBPs) such as TDP-43 or FUS are largely soluble in the nucleus, but form solid pathological aggregates when mislocalized to the cytoplasm. What keeps these proteins soluble in the nucleus and promotes aggregation in the cytoplasm is still unknown. We report here that RNA critically regulates the phase behavior of prion-like RBPs. Low RNA/protein ratios promote phase separation into liquid droplets, whereas high ratios prevent droplet formation in vitro. Reduction of nuclear RNA levels or genetic ablation of RNA binding causes excessive phase separation and the formation of cytotoxic solid-like assemblies in cells. We propose that the nucleus is a buffered system in which high RNA concentrations keep RBPs soluble. Changes in RNA levels or RNA binding abilities of RBPs cause aberrant phase transitions.

Massab Umair , Muhammad Salman , Muhammad Masroor Alam , Muhammad S. Rana , Syed S.Z. Zaidi , Michael D. Bowen , Uzma B. Aamir , Bilal H. Abbasi

The G12 rotavirus genotype has emerged globally since their first detection in 1987 from the Philippines; however it remains a rare cause of gastroenteritis in Pakistan. Rotavirus surveillance conducted during 2015‐2016, assessed 3446 children …

Abstract Background The ability of Staphylococcus aureus to invade tissues and cause an infectious disease is the result of a multi-factorial process supported by the huge number of virulence factors inherent to this microorganism tightly regulated by the accessory gene regulator (agr). During antimicrobial therapy bacteria may be exposed to sub-inhibitory concentrations (subMICs) of antibiotics that may trigger transcriptional changes that may have an impact on the pathogenesis of infection. The objective of this study was to investigate the effect of oxacillin sub-MICs on agr system expression as the key component in the regulation of virulence in methicillin-susceptible (MSSA) and -resistant S. aureus (MRSA) strains. Furthermore, we studied the genetic basis of the agr locus and their potential association with the expression levels. Methods We have examined the expression of RNAIII and agrA mRNA as biomarkers for agr expression in the presence and absence of oxacillin subMICs in 10 MSSA and 4 MRSA clinical strains belonging to 5 clonal complexes (CC45-agrI, CC8-agrI, CC5-agrII, CC15-agrII and CC30-agrIII) causing endovascular complications. The DNA sequences of agr locus were obtained by whole genome sequencing. Results Our results revealed that exposure to subMICs of oxacillin had an impact on agr locus expression modifying the relative levels of expression with increases in 11 strains and with decreases in 3 strains. Thereby, the exposure to subMICs of oxacillin resulted in higher levels of expression of agr in CC15 and CC45 and lower levels in CC30. We also observed the presence of mutations in agrC and agrA in 13/14 strains with similar mutation profiles among strains within individual CCs except for strains of CC5. Although, agr expression levels differed among strains within CCs, the presence of these mutations was associated with differences in agr expression levels in most cases. Conclusions Changes in agr expression induced by exposure to oxacillin subMICs should be considered because they could lead to changes in the virulence modulation and have an adverse effect on the course of infection, especially in certain clonal complexes.

A. Wahnich et al.

Abstract Background Zika virus (ZIKV) infection is a pandemic and a public health emergency. It is transmitted by mosquitoes, primarily the Aedes genus. In light of no treatment currently, it is crucial to develop effective vector control programs to prevent the spread of ZIKV infection earlier when observing possible risk factors, such as weather conditions enhancing mosquito breeding and surviving. Methods This study collected daily meteorological measurements and weekly ZIKV infectious cases among 32 departments of Colombia from January 2015–December 2016. This study applied the distributed lag nonlinear model to estimate the association between the number of ZIKA virus infection and meteorological measurements, controlling for spatial and temporal variations. We examined at most three meteorological factors with 20 lags in weeks in the model. Results Average humidity, total rainfall, and maximum temperature were more predictable of ZIKV infection outbreaks than other meteorological factors. Our models can detect significantly lagged effects of average humidity, total rainfall, and maximum temperature on outbreaks up to 15, 14, and 20 weeks, respectively. The spatial analysis identified 12 departments with a significant threat of ZIKV, and eight of those high-risk departments were located between the Equator and 6°N. The outbreak prediction also performed well in identified high-risk departments. Conclusion Our results demonstrate that meteorological factors could be used for predicting ZIKV epidemics. Building an early warning surveillance system is important for preventing ZIKV infection, particularly in endemic areas.

Wong, A., Grau, M. A., Singh, A. K., Woodiga, S. A., King, S. J.

Streptococcus gordonii is an early colonizer of the oral cavity. Although a variety of S. gordonii adherence mechanisms have been described, current dogma is that the major receptor for S. gordonii is sialic acid. However, as many bacterial species in the oral cavity produce neuraminidase that can cleave terminal sialic acid, it is unclear whether S. gordonii relies on sialic acid for adherence to oral surfaces or if this species has developed alternative binding strategies. Previous studies have examined adherence to immobilized glycoconjugates and identified binding to additional glycans; but no prior studies have defined the contribution of these different glycan structures in adherence to oral epithelial cells. We determined that the majority of S. gordonii strains tested did not rely on sialic acid for efficient adherence. In fact, adherence of some strains was significantly increased following neuraminidase treatment. Further investigation of representative strains that do not rely on sialic acid for adherence revealed binding not only to sialic acid via the serine-rich repeat protein GspB, but also to β-1,4-linked galactose. Adherence to this carbohydrate occurs via an unknown adhesin distinct from those utilized by Streptococcus oralis and Streptococcus pneumoniae. Demonstrating the potential biological relevance of binding to this cryptic receptor, we established that S. oralis increases S. gordonii adherence in a neuraminidase-dependent manner. These data suggest that S. gordonii has evolved to simultaneously utilize both terminal and cryptic receptors in response to the production of neuraminidase by other species in the oral environment.

Friedrich MJ.

The World Health Organization (WHO) issued updated and consolidated guidelines for people with latent tuberculosis infection (LTBI) that aims to expand testing and improve treatment. The WHO simultaneously released a mobile application to support systematic monitoring and evaluation of patients with LTBI that can be adapted to meet country-specific contexts, such as national surveillance systems.

Friedrich MJ.

More than 1 round of mass administration of azithromycin may be needed to eradicate yaws, an infectious disease caused by the bacterium Treponema pallidum subspecies pertenue, according to a report published in the Lancet.