Destination Area: Global Systems Science (GSS)
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GSS fosters transdisciplinary study of the dynamic interplay between natural and social systems. Faculty in this area collaborate to discover creative solutions to critical social problems emergent from human activity and environmental change, in areas such as freshwater and coastal water systems, rural environments, infectious disease, and food production and safety. Work in this area also embraces equity in the human condition by seeking the equitable distribution and availability of physical safety and well-being, psychological well-being, respect for human dignity, and access to crucial material and social resources throughout the world’s diverse communities.
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Browsing Destination Area: Global Systems Science (GSS) by Subject "0605 Microbiology"
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- Determinants of dengue virus dispersal in the AmericasAllicock, Orchid M.; Sahadeo, Nikita; Lemey, Philippe; Auguste, A. Jonathan; Suchard, Marc A.; Rambaut, Andrew; Carrington, Christine V. F. (Oxford University Press, 2020-07)Dengue viruses (DENVs) are classified into four serotypes, each of which contains multiple genotypes. DENV genotypes introduced into the Americas over the past five decades have exhibited different rates and patterns of spatial dispersal. In order to understand factors underlying these patterns, we utilized a statistical framework that allows for the integration of ecological, socioeconomic, and air transport mobility data as predictors of viral diffusion while inferring the phylogeographic history. Predictors describing spatial diffusion based on several covariates were compared using a generalized linear model approach, where the support for each scenario and its contribution is estimated simultaneously from the data set. Although different predictors were identified for different serotypes, our analysis suggests that overall diffusion of DENV-1, -2, and -3 in the Americas was associated with airline traffic. The other significant predictors included human population size, the geographical distance between countries and between urban centers and the density of people living in urban environments.
- Diversity and Dynamics of Salmonella enterica in Water Sources, Poultry Litters, and Field Soils Amended With Poultry Litter in a Major Agricultural Area of VirginiaGu, Ganyu; Strawn, Laura K.; Zheng, Jie; Reed, Elizabeth A.; Rideout, Steven L. (Frontiers, 2019-12-17)The Eastern Shore of Virginia (ESV) is a major agricultural region in Virginia and in the past has been linked to some tomato-associated outbreaks of salmonellosis. In this study, water samples were collected weekly from irrigation ponds and wells in four representative vegetable farms (Farms A–D, each farm paired with one pond and one well) and a creek as well. In addition, water samples from two sites in the Chesapeake Bay on the ESV were collected monthly. Poultry litter was sampled monthly from three commercial broiler farms. Soil samples were collected monthly after fertilization with poultry litter from 10 farms in 2014 and another 14 farms in 2015. A most probable number method was used to detect Salmonella enterica presence and concentration in collected samples. Presumptive Salmonella colonies were confirmed by the cross-streaking method. Molecular serotyping was carried out to determine the Salmonella serovars. The average prevalence of Salmonella in pond, well, creek, and bay water samples was 19.3, 3.3, 24.2, and 29.2%, respectively. There were significant spatial and temporal differences for Salmonella incidence in various water sources. The prevalence of S. enterica in four tested ponds from farms A, B, C, and D were 16, 12, 22, and 27%, respectively. While the prevalence of S. enterica in irrigation wells was significantly lower, some well water samples tested positive during the study. Salmonella Newport was found to be the predominant serovar isolated from water samples. All poultry houses of the three tested broiler farms were Salmonella-positive at certain sampling points during the study with prevalence ranging from 14.3 to 35.4%. Salmonella was found to be able to survive up to 4 months in poultry litter amended soils from the tested farms in 2014, and up to 6 months in 2015. This research examined the dynamics of S. enterica in relationship to water source, poultry litter, and amended soil in a major agricultural area, and provides useful information for food safety risk assessments.
- Evaluation of Metagenomic-Enabled Antibiotic Resistance Surveillance at a Conventional Wastewater Treatment PlantMajeed, Haniyyah J.; Riquelme, Maria V.; Davis, Benjamin C.; Gupta, Suraj; Angeles, Luisa F.; Aga, Diana S.; Garner, Emily; Pruden, Amy; Vikesland, Peter J. (Frontiers, 2021-05-13)Wastewater treatment plants (WWTPs) receive a confluence of sewage containing antimicrobials, antibiotic resistant bacteria, antibiotic resistance genes (ARGs), and pathogens and thus are a key point of interest for antibiotic resistance surveillance. WWTP monitoring has the potential to inform with respect to the antibiotic resistance status of the community served as well as the potential for ARGs to escape treatment. However, there is lack of agreement regarding suitable sampling frequencies and monitoring targets to facilitate comparison within and among individual WWTPs. The objective of this study was to comprehensively evaluate patterns in metagenomic-derived indicators of antibiotic resistance through various stages of treatment at a conventional WWTP for the purpose of informing local monitoring approaches that are also informative for global comparison. Relative abundance of total ARGs decreased by ∼50% from the influent to the effluent, with each sampling location defined by a unique resistome (i.e., total ARG) composition. However, 90% of the ARGs found in the effluent were also detected in the influent, while the effluent ARG-pathogen taxonomic linkage patterns identified in assembled metagenomes were more similar to patterns in regional clinical surveillance data than the patterns identified in the influent. Analysis of core and discriminatory resistomes and general ARG trends across the eight sampling events (i.e., tendency to be removed, increase, decrease, or be found in the effluent only), along with quantification of ARGs of clinical concern, aided in identifying candidate ARGs for surveillance. Relative resistome risk characterization further provided a comprehensive metric for predicting the relative mobility of ARGs and likelihood of being carried in pathogens and can help to prioritize where to focus future monitoring and mitigation. Most antibiotics that were subject to regional resistance testing were also found in the WWTP, with the total antibiotic load decreasing by ∼40–50%, but no strong correlations were found between antibiotics and corresponding ARGs. Overall, this study provides insight into how metagenomic data can be collected and analyzed for surveillance of antibiotic resistance at WWTPs, suggesting that effluent is a beneficial monitoring point with relevance both to the local clinical condition and for assessing efficacy of wastewater treatment in reducing risk of disseminating antibiotic resistance.
- Impact of extrinsic incubation temperature on natural selection during Zika virus infection of Aedes aegypti and Aedes albopictusMurrieta, Reyes A.; Garcia-Luna, Selene M.; Murrieta, Deedra J.; Halladay, Gareth; Young, Michael C.; Fauver, Joseph R.; Gendernalik, Alex; Weger-Lucarelli, James; Rückert, Claudia; Ebel, Gregory D. (PLoS, 2021-11-09)Arthropod-borne viruses (arboviruses) require replication across a wide range of temperatures to perpetuate. While vertebrate hosts tend to maintain temperatures of approximately 37°C-40°C, arthropods are subject to ambient temperatures which can have a daily fluctuation of > 10°C. Temperatures impact vector competence, extrinsic incubation period, and mosquito survival unimodally, with optimal conditions occurring at some intermediate temperature. In addition, the mean and range of daily temperature fluctuations influence arbovirus perpetuation and vector competence. The impact of temperature on arbovirus genetic diversity during systemic mosquito infection, however, is poorly understood. Therefore, we determined how constant extrinsic incubation temperatures of 25°C, 28°C, 32°C, and 35°C control Zika virus (ZIKV) vector competence and population dynamics within Aedes aegypti and Aedes albopictus mosquitoes. We also examined fluctuating temperatures which better mimic field conditions in the tropics. We found that vector competence varied in a unimodal manner for constant temperatures peaking between 28°C and 32°C for both Aedes species. Transmission peaked at 10 days post-infection for Aedes aegypti and 14 days for Aedes albopictus. Conversely, fluctuating temperature decreased vector competence. Using RNA-seq to characterize ZIKV population structure, we identified that temperature alters the selective environment in unexpected ways. During mosquito infection, constant temperatures more often elicited positive selection whereas fluctuating temperatures led to strong purifying selection in both Aedes species. These findings demonstrate that temperature has multiple impacts on ZIKV biology, including major effects on the selective environment within mosquitoes.
- Pleiotropic Odorant-Binding Proteins Promote Aedes aegypti Reproduction and Flavivirus TransmissionDong, Shengzhang; Ye, Zi; Tikhe, Chinmay Vijay; Tu, Zhijian Jake; Zwiebel, Laurence J.; Dimopoulos, George (American Society for Microbiology, 2021-09-01)Insect odorant-binding proteins (OBPs) are small soluble proteins that have been assigned roles in olfaction, but their other potential functions have not been extensively explored. Using CRISPR/Cas9-mediated disruption of Aedes aegypti Obp10 and Obp22, we demonstrate the pleiotropic contribution of these proteins to multiple processes that are essential for vectorial capacity. Mutant mosquitoes have impaired host-seeking and oviposition behavior, reproduction, and arbovirus transmission. Here, we show that Obp22 is linked to the male-determining sex locus (M) on chromosome 1 and is involved in male reproduction, likely by mediating the development of spermatozoa. Although OBP10 and OBP22 are not involved in flavivirus replication, abolition of these proteins significantly reduces transmission of dengue and Zika viruses through a mechanism affecting secretion of viral particles into the saliva. These results extend our current understanding of the role of insect OBPs in insect reproduction and transmission of human pathogens, making them essential determinants of vectorial capacity. IMPORTANCE Aedes aegypti is the major vector for many arthropod-borne viral diseases, such as dengue, Zika, and chikungunya viruses. Previous studies suggested that odorant-binding proteins (OBPs) may have diverse physiological functions beyond the olfactory system in mosquitoes; however, these hypothesized functions have not yet been demonstrated. Here, we have used CRISPR/Cas9-based genome editing to functionally delete (knock out) Obp10 and Obp22 in Aedes aegypti. We showed that disruption of Obp10 or Obp22 significantly impairs female and male reproductive capacity by adversely affecting blood feeding, oviposition, fecundity and fertility, and the development of spermatozoa. We also showed that disruption of Obp10 or Obp22 significantly reduces the transmission of dengue and Zika viruses through a mechanism affecting secretion of viral particles into the saliva. Thus, our study is not only significant in understanding the functions of OBPs in mosquito biology, but also shows that OBPs may represent potent flavivirus transmission-blocking targets. Our study is in this regard particularly timely and important from a translational and public health perspective.