Strain Variability Research Articles

Intra-species variability inFusarium langsethiae strains in growth and T-2/HT-2 mycotoxin production in response to climate change abiotic factors

The objective of this study was to evaluate the potential intra-species variability of 3Fusarium langsethiae strains in response to extreme climate change (CC) conditions on an oat-based matrix. The impact of elevated temperature (25 vs 30-34 °C) coupled with increasing drought stress (0.98 vs 0.95 aw) and elevated CO2 (400 vs 1000 ppm) were examined on lag phases prior to growth, growth rate, and production of the mycotoxins T-2 and HT-2 and their ratio. In comparison to the control conditions (25 °C; 0.98; 400 ppm), exposure to increased temperature (30-34 °C), showed similar reductions in the lag phase and fungal growth rates of all 3 strains. However, with elevated CO2 a reduction in both lag phases prior to growth and growth rate occurred regardless of the aw examined. For T-2 and HT-2 mycotoxin production, T-2 showed the most intra-species variability in response to the interacting abiotic stress factors, with the 3 strains having different environmental conditions for triggering increases in T-2 production: Strain 1 produced higher T-2 toxin at 25 °C, while Strain 2 and the type strain (Fl201059) produced most at 0.98 aw/30 °C. Only Strain 2 showed a reduction in toxin production when exposed to elevated CO2. HT-2 production was higher at 25 °C for the type strain and higher at 30-34 °C for the other two strains, regardless of the aw or CO2 level examined. The HT-2/T-2 ratio showed no significant differences due to the imposed interacting CC abiotic conditions.

Genetic Variability of Nile Tilapia Strains as Determined by Microsatellite DNA Markers

AbstractThe main purpose of the present study was to investigate the genetic variability of Nile Tilapia Oreochromis niloticus strains by using microsatellite DNA markers and to compare these data with those previously obtained with single‐nucleotide polymorphisms (SNPs). Five mixed‐sex strains and four YY‐male strains were analyzed. All nine microsatellite loci were polymorphic; the number of unique alleles per locus varied from 6 at UNH216 to 33 at UNH880. Strong correspondence was observed between the level of expected heterozygosity (He) or observed heterozygosity and the number of alleles per locus (A) or the number of private alleles. Strains with high levels of heterozygosity typically had higher values of A and the presence of private alleles. In general, mixed‐sex strains had higher genetic variability than YY‐male strains. Four mixed‐sex strains (GIFT, Ismailia Canal, LSA hybrid, and Miami) had the highest level of genetic variability, with mean He ranging from 0.630 to 0.798 and mean A ranging from 5.11 to 9.78. Three YY‐male strains (Fishgen YY Dark–Group 2, Fishgen YY Red, and Til‐Aqua YY) had low genetic variability, with mean He ranging from 0.282 to 0.367 and mean A ranging from 1.89 to 3.56. All investigated strains demonstrated low values of the inbreeding coefficient FIS (from –0.266 to 0.014), suggesting that mating of closely related individuals is being avoided during maintenance of these strains. Pairwise genetic differentiation index FST values had a broad range (from 0.0915 to 0.6063), indicating different levels of genetic differentiation between strains. A dendrogram constructed according to shared allele distance showed the existence of two distinct clusters among strains. The present data on genetic variability of Nile Tilapia strains demonstrated substantial similarity with data from a previous study of SNPs in the same populations.

Phylogenetic analysis of VP7 and VP4 genes of the most predominant human group A rotavirus G12 identified in children with acute gastroenteritis in Himachal Pradesh, India during 2013-2016.

G12 strains are now considered to be the sixth most prevalent human rotaviruses globally. India has introduced rotavirus vaccine Rotavac® into the national immunization program in 2016 and Himachal Pradesh (HP) is the first state to launch it. During epidemiological rotavirus surveillance in HP, predominance of G12 rotaviruses was observed. This study investigated the genetic variability and evolution of HP G12 strains (n = 15) associated with P-genotypes P[6], P[4], and P[8] identified between 2013 and 2016. Phylogenetic analysis of VP7 gene revealed that all characterized G12 strains clustered in lineage-III and diversified into three subclusters indicating that these strains may have originated from three different ancestral G12 strains. The comparative sequence analysis of HP strains with Rotavac® and Rotarix® vaccine strains revealed various amino acid substitutions in epitope regions of VP7 and VP4 proteins especially at the antibody neutralization sites. Only 12/29 VP7 epitope residues and 2/25 VP4 epitope residues were found to be conserved between HP rotavirus strains and vaccine strains. Both long and short electropherotypes were observed in G12P[4] strains, while a single long electropherotype was observed in G12P[6] strains. Children of ≤11 months were significantly infected with G12 rotaviruses. The frequency of vomiting episodes (≥5/day) was significantly higher in children infected with G12 rotavirus strains as compared to non-G12 rotaviruses (p = 0.0405). Our study provides the comprehensive data on clinical characteristics and evolutionary pattern of the G12 rotavirus, the most prevalent strain in HP and emphasizes the need to monitor these strains for inclusion in future vaccine.

Secondary Modeling and Strain Variability of Listeria monocytogenes Isolated from Seafood and Clinical Samples at Various Environmental Conditions Using High-Throughput Turbidity Method

Background and Objective: Variability of foodborne pathogens plays important roles in microbial risk assessment. In the present study, kinetic behaviors of seven Listeria monocytogenes and two Listeria innocua strains from various sources were assessed at various pH (4.5, 5.0, 5.5, 6.8 and 7.0) and salinity (0.5, 2.5, 3.5, 5, 7 and 10% NaCl). Material and Methods: Maximum specific growth rates (µmax) were assessed using Bioscreen C (time-to-detection method). Nearly 1500 curves were produced for Listeria monocytogenes and Listeria innocua strains and secondary models were developed for the bacteria as a function of NaCl, pH, temperature and undissociated lactic acid concentrations. Results and Conclusion: Variability of µmax enhanced as the growth environment became unfavorable. Coefficient of variation of µmax in Listeria monocytogenes strains were 6.5 and 20% at 0.5 and 7.5% NaCl (pH 7.26), respectively. After selecting the most robust strain, models demonstrating relationships between the growth rate and environmental conditions (NaCl, pH and undissociated form of lactic acid) were generated using Origin 2018 Software and polynomial and nonlinear surface fitting. In conclusion, intraspecies variability of the growth kinetic behaviors and developed models based on the worst case (e.g., the most robust Listeria monocytogenes strain) include important uses in food industries. Conflict of interest: The authors declare no conflict of interest.

Evidence of Circulation of Several HAV Genetic Variants and Emergence of Potential Antigenic Variants in an Endemo-Epidemic Country before Vaccine Introduction.

Similar to several other countries in the world, the epidemiology of hepatitis A virus changed from high to intermediate endemicity level in Tunisia, which led to the occurrence of outbreaks. This study aimed to determine the genetic and antigenic variability of HAV strains circulating in Tunisia during the last few years. Genotyping using complete VP1 gene and VP1-2A junction confirmed the predominance of genotype IA, with co-circulation of several genetic and antigenic variants. Phylogenetic analysis including Tunisian and strains from other regions of the world showed the presence of at least two IA-variants within IA subgenotype. Amino-acid analysis showed several mutations in or close to epitope regions in the VP1-region. This study provides a baseline on the genetic and antigenic variability of HAV circulating strains before the introduction of vaccination into the national immunization schedule.

Evaluation of Strain Variability in Inactivation of Campylobacter jejuni in Simulated Gastric Fluid by Using Hierarchical Bayesian Modeling.

This study was conducted to quantitatively evaluate the variability of stress resistance in different strains of Campylobacter jejuni and the uncertainty of such strain variability. We developed Bayesian statistical models with multilevel analysis to quantify variability within a strain, variability between different strains, and the uncertainty associated with these estimates. Furthermore, we measured the inactivation of 11 strains of C. jejuni in simulated gastric fluid with low pH, using the Weibullian survival model. The model was first developed for separate pH conditions and then analyzed over a range of pH levels. We found that the model parameters developed under separate pH conditions exhibited a clear dependence of survival on pH. In addition, the uncertainty of the variability between different strains could be described as the joint distribution of the model parameters. The latter model, including pH dependency, accurately predicted the number of surviving cells in individual as well as multiple strains. In conclusion, variabilities and uncertainties in inactivation could be simultaneously evaluated and interpreted via a probabilistic approach based on Bayesian theory. Such hierarchical Bayesian models could be useful for understanding individual-strain variability in quantitative microbial risk assessment. IMPORTANCE Since microbial strains vary in their growth and inactivation patterns in food materials, it is important to accurately predict these patterns for quantitative microbial risk assessment. However, most previous studies in this area have used highly resistant strains, which could lead to inaccurate predictions. Moreover, variability, including measurement errors and variability within a strain and between different strains, can contribute to predicted individual-level outcomes. Therefore, a multilevel framework is required to resolve these levels of variability and estimate their uncertainties. We developed a Bayesian predictive model for the survival of Campylobacter jejuni under simulated gastric conditions taking into account the variabilities and uncertainties. We demonstrated a high correspondence between predictions from the model and empirical measurements. The modeling procedure proposed in this study recommends a novel framework for predicting pathogen behavior, which can help improve quantitative microbial risk assessment during food production and distribution.

Selective cannabis strain allergy in a patient presenting with a local allergic reaction

BackgroundCannabis use is growing domestically due to recent legalization in many jurisdictions. There are two main species of cannabis, Cannabis sativa and Cannabis indica, and thousands of different commercially available cannabis strains. Although there are multiple reports of cannabis allergy in the literature, to our knowledge, there is no prior published report of selective cannabis strain allergy.Case presentationA 31-year-old male was referred for allergy assessment due to several episodes of localized pruritus and erythema after direct contact with various strains of cannabis. He had noted that the severity of his reaction appeared to be strain dependent. He developed a severe local reaction involving bilateral periorbital edema shortly after coming into direct contact with one particular strain of cannabis. He denied any adverse symptoms after inhalation of cannabis. Fresh skin prick testing was performed to various strains of cannabis and had positive testing to the three of the five tested strains.ConclusionsWe believe this is the first reported case of selective cannabis strain allergy based on patient history and skin prick testing. This case report outlines the variability in different strains of cannabis and stresses the importance of further research into cannabis allergen identification. Multiple cannabis allergens should be included and incorporated into commercial extracts when they become routinely available.

Thermomechanical characteristics of an energy pile-raft foundation under heating operations

This study aims to comprehensively explore the thermomechanical characteristics of energy pile-raft foundations through in situ full-scale field tests. The foundation of interest was subjected to the joint effect of building loading and cooling thermal loading. The temperature, strain, and stress variability in both the employed pile and raft were measured and analysed. The basement of the building acted as an insulator, and the near-surface ground temperatures under the basement were affected less by seasonal changes in the air temperature. The stabilized heat exchange rate of the energy pile was approximately 75.0 W/m. The overlying raft and building at the pile head and the expanded foot and sandstone at the pile toe imposed greater restraints than those observed at other parts of the pile. The thermally induced stress per centigrade near the pile head and toe was approximately −0.160 MPa/°C and −0.202 MPa/°C, respectively. The thermally induced stresses of this kind of pile were mostly stabilized after 16 days of heating operation. When the pile was under thermomechanical loading, the axial tensile stress was mobilized along the lower half of the pile, and the maximum measured tensile stress was approximately 0.25 MPa, which did not exceed the tensile strength of the employed concrete. The cooling (contracting) of the energy pile also influenced the nearby raft. The raft temperature decreased by 6.2 °C, and the additional tensile stress was approximately 0.88 MPa (40.0% of the upper bound).

Molecular characterization of porcine group A rotavirus to contain piglet diarrhea for productivity enhancement in North East India.

Gastrointestinal tract infections with acute diarrhea are indeed a serious cause of concern that held back the swine industry of North East India and among the various etiological agents causing the disease, group A rotavirus is the most common. In this regard, molecular characterization of the viral strains circulating in the region is of utmost importance for a strategic approach to control the disease. Thus, in the present study, diarrheic fecal samples from piglets of Tripura and Assam were evaluated for genotypic characterization of VP7 and VP4 gene of the virus. The samples positive for group A rotavirus were subjected to G and P type determination by nested- multiplex RT PCR as well as nucleotide sequencing of VP7 and VP4 gene. Nested- multiplex RT PCR revealed the presence of porcine group A rotavirus in the genotypic combination of G1P[6], G3P[6], G8P[6] and G4P[6] in the two states of North East India. Nucleotide sequencing of VP7 and VP4 genes however, revealed emergence of an unusual genotypic combination G26P[13]. VP7 and VP4 nucleotide and its deduced amino acid sequences when compared with global isolates, showed that the present strains shared closest similarity to the porcine rotavirus strain TJ4-1from Japan and hp140 from Eastern India. Identification of a novel genotype G26P[13] in the RVA infected pig population of Tripura and Assam, suggested presence of a greater diversity in rotavirus strains in the region. Thus, it evokes the need for continuous monitoring to assess and consider the strain variability in the design of a suitable vaccine candidate against the virus. Supplementary InformationThe online version of this article (10.1007/s13337-021-00659-6) contains supplementary material, which is available to authorized users.

Left ventricular ejection fraction and Global Longitudinal Strain variability between methodology and experience.

Although ejection fraction (EF) is the cornerstone of the assessment of left ventricular (LV) systolic function, its measurement faces a number of challenges related to image quality, assumptions of LV geometry, and expertise. The aim of this study was to test the inter-observer variability of EF and GLS measurement in patients with a broad spectrum of LV function, between physicians and investigators (Inv) with different levels of expertise. In 122 patients, EF and GLS were measured by 4 Inv blinded to each other with different level of experience in echocardiography; EF was measured using 3 methods: visual assessment, biplane Simpson's method, and auto-EF method. GLS was measured from the 3 apical views. A significant difference for LVEF and for LVGLS was considered to be >10 and >2 absolute values, respectively. Intra-observer agreement was excellent for visually assessed EF (ICC=0.87, P<.001) and GLS (ICC=0.82, P<.001) and good for EF measured by Simpson's method (ICC=0.70, P<.001) and auto-EF (ICC=0.72, P<.001). Intra-observer and inter-observer agreements were excellent for GLS with ICCs above 0.8. GLS discordance between the 4 Inv was not significant. Discordance in EF and GLS measurements among the Inv was not related to image quality or wall motion abnormalities. Although EF has proved its prognostic value in various cardiovascular entities, GLS seems to be more reliable for serial assessment of LV function, demonstrating lower intra- and inter-observer variability, even by different physicians with variant level of expertise.

Advanced Killing Potential of Thymol against a Time and Temperature Optimized Attached Listeria monocytogenes Population in Lettuce Broth.

Fresh vegetables and salads are increasingly implicated in outbreaks of foodborne infections, such as those caused by Listeria monocytogenes, a dangerous pathogen that can attach to the surfaces of the equipment creating robust biofilms withstanding the killing action of disinfectants. In this study, the antimicrobial efficiency of a natural plant terpenoid (thymol) was evaluated against a sessile population of a multi-strain L. monocytogenes cocktail developed on stainless steel surfaces incubated in lettuce broth, under optimized time and temperature conditions (54 h at 30.6 °C) as those were determined following response surface modeling, and in comparison, to that of an industrial disinfectant (benzalkonium chloride). Prior to disinfection, the minimum bactericidal concentrations (MBCs) of each compound were determined against the planktonic cells of each strain. The results revealed the advanced killing potential of thymol, with a concentration of 625 ppm (= 4 × MBC) leading to almost undetectable viable bacteria (more than 4 logs reduction following a 15-min exposure). For the same degree of killing, benzalkonium chloride needed to be used at a concentration of at least 20 times more than its MBC (70 ppm). Discriminative repetitive sequence-based polymerase chain reaction (rep-PCR) also highlighted the strain variability in both biofilm formation and resistance. In sum, thymol was found to present an effective anti-listeria action under environmental conditions mimicking those encountered in the salad industry and deserves to be further explored to improve the safety of fresh produce.

Defining the optimal temporal and spatial resolution for cardiovascular magnetic resonance imaging feature tracking

BackgroundMyocardial deformation analyses using cardiovascular magnetic resonance (CMR) feature tracking (CMR-FT) have incremental value in the assessment of cardiac function beyond volumetric analyses. Since guidelines do not recommend specific imaging parameters, we aimed to define optimal spatial and temporal resolutions for CMR cine images to enable reliable post-processing.MethodsIntra- and inter-observer reproducibility was assessed in 12 healthy subjects and 9 heart failure (HF) patients. Cine images were acquired with different temporal (20, 30, 40 and 50 frames/cardiac cycle) and spatial resolutions (high in-plane 1.5 × 1.5 mm through-plane 5 mm, standard 1.8 × 1.8 x 8mm and low 3.0 × 3.0 x 10mm). CMR-FT comprised left ventricular (LV) global and segmental longitudinal/circumferential strain (GLS/GCS) and associated systolic strain rates (SR), and right ventricular (RV) GLS.ResultsTemporal but not spatial resolution did impact absolute strain and SR. Maximum absolute changes between lowest and highest temporal resolution were as follows: 1.8% and 0.3%/s for LV GLS and SR, 2.5% and 0.6%/s for GCS and SR as well as 1.4% for RV GLS. Changes of strain values occurred comparing 20 and 30 frames/cardiac cycle including LV and RV GLS and GCS (p < 0.001–0.046). In contrast, SR values (LV GLS/GCS SR) changed significantly comparing all successive temporal resolutions (p < 0.001–0.013). LV strain and SR reproducibility was not affected by either temporal or spatial resolution, whilst RV strain variability decreased with augmentation of temporal resolution.ConclusionTemporal but not spatial resolution significantly affects strain and SR in CMR-FT deformation analyses. Strain analyses require lower temporal resolution and 30 frames/cardiac cycle offer consistent strain assessments, whilst SR measurements gain from further increases in temporal resolution.

Improved evaluation of the genetic variability of Brazilian strains of Erwinia psidii with newly developed microsatellite markers

AbstractErwinia psidii is the causal agent of bacterial blight of guava, and wilt and dieback of eucalypt in Brazil. Previous studies using repetitive sequence‐based PCR (rep‐PCR) revealed limited genetic diversity in E. psidii populations. Here, the draft genome sequence of the type strain IBSBF435 was probed for variable number of tandem repeats (VNTRs) that could be used to study E. psidii genetic diversity by multilocus variable number of tandem repeat analysis (MLVA). Eleven selected VNTRs were used to assess genetic relatedness among 108 E. psidii strains from guava (36) and eucalypt (72), of different geographic origins and years of collection. A total of 79 haplotypes were detected in the strain collection. The number of alleles per locus ranged from 3 to 15. A minimum spanning tree indicated the occurrence of nine clonal complexes, of which two contained only guava strains, five only eucalypt strains, and two contained guava and eucalypt strains. The three oldest strains collected from guava in the 1980s (IBSBF435, IBSBF454, and IBSBF493) exhibited distinct haplotypes. IBSBF435 was genetically more closely related to some eucalypt strains than to guava strains, which supports previously reported lack of host specificity. IBSBF454 grouped with guava strains more recently collected from different states, suggesting that it could have been disseminated to different Brazilian areas. The implication of the lack of differentiation between guava and eucalypt strains is discussed in relation to the detection of E. psidii affecting eucalypt more than 25 years after the first description of guava bacterial blight.

The effect of water availability on growth strain in Eucalyptus grandis-urophylla trees

The Eucalyptus genus is the most widely planted hardwood worldwide. It is, however, mostly used for low value products as a result of various wood quality problems. Splitting and distortion of wood due to growth stresses is arguably the most critical quality issue for this genus. In this research, the effect of water availability on the peripheral and internal longitudinal growth strain of 7-year-old Eucalyptus grandis-urophylla trees was investigated. A new method using a custom modified digital dial gauge was developed for measuring the internal growth strain variability in standing trees – the first such method according to the best of our knowledge. Growth strain was measured on three sites with different water availability. The results showed that not only peripheral but also internal longitudinal growth strain was significantly affected by the water availability. Trees from the wet site showed higher surface and internal growth strain, while the trees planted on the dry site indicated lower and more uniform growth strain distribution inside their stems. Apart from the water availability, the direction of the prevailing wind was found as another influencing factor on growth strain. Both the radial and longitudinal patterns of longitudinal growth strains were determined and the results showed that growth strain decreased with height and that the neutral points of strain for all sites were between 8 and 9 tenths of the diameter from the pith. Growth strain was also measured destructively on logs and it was found that there was a significant difference between the growth strains of the logs from the same height but from different sites. The results also showed that, on the same log, the end split length per area of log cross section occurring during cross cutting could be modelled moderately well with a linear regression equation (R2 = 0.67). The model included the variables maximum compressive strain over the radius, the maximum difference of compressive and tensile strain (between south and east directions) and the sum of strain difference over the radius between adjacent points divided by the diameter.

Secondary Aroma: Influence of Wine Microorganisms in Their Aroma Profile.

Aroma profile is one of the main features for the acceptance of wine. Yeasts and bacteria are the responsible organisms to carry out both, alcoholic and malolactic fermentation. Alcoholic fermentation is in turn, responsible for transforming grape juice into wine and providing secondary aromas. Secondary aroma can be influenced by different factors; however, the influence of the microorganisms is one of the main agents affecting final wine aroma profile. Saccharomyces cerevisiae has historically been the most used yeast for winemaking process for its specific characteristics: high fermentative metabolism and kinetics, low acetic acid production, resistance to high levels of sugar, ethanol, sulfur dioxide and also, the production of pleasant aromatic compounds. Nevertheless, in the last years, the use of non-saccharomyces yeasts has been progressively growing according to their capacity to enhance aroma complexity and interact with S. cerevisiae, especially in mixed cultures. Hence, this review article is aimed at associating the main secondary aroma compounds present in wine with the microorganisms involved in the spontaneous and guided fermentations, as well as an approach to the strain variability of species, the genetic modifications that can occur and their relevance to wine aroma construction.

Incorporating strain variability in the design of heat treatments: A stochastic approach and a kinetic approach

For the design of thermal processes, the decimal reduction times (D-values) of target organisms can be used. However, many factors influence the D-value, like inherent organism’s characteristics (strain variability), the effect of the history of the cells, as well as product factors and process factors. Strain variability is a very large contributor to the overall variation of the D-value. Hence, the overall reduction of microbial contaminants by a heat treatment is a combination of the occurrence of a strain with a certain heat resistance and its reduction given the prevailing conditions. This reduction can be determined using two approaches: a kinetic analysis based on integral equations or a stochastic approach based on Monte Carlo analysis. In this article, these two approaches are compared using as case studies the inactivation of two microorganisms: Listeria monocytogenes in a pasteurization process and the sporeformer Geobacillus stearothermophilus in a UHT process. Both approaches resulted in similar conclusions, highlighting that the strains with the highest heat resistance are determinant for the overall inactivation, even if the probability of cells having such extreme heat resistance is very low.

Detection and Phylogenetic Analysis of Fish Viruses Inhabiting Freshwater Ornamental and Food Fish Species in India: A Survey-Based Study

Molecular screening of viruses through PCR is a fast detection method and several variants of it have been developed to meet the shortcomings of conventional method. Extensive surveillance is an essential tool to have an estimate of circulating potential viruses in Indian aquatic systems. The present study focuses on standardization of semi-quantitative PCR-based diagnostics for eight freshwater fish viral pathogens and documents number of positive incidences after screening 437 numbers of samples during 2017-2020 for suspected fifteen freshwater finfish viral pathogens. Positive samples of Cyprinid herpes virus-2, carp edema virus and viral nervous necrosis virus from different regions of eastern Indian states viz., Odisha, West Bengal and Assam have given a scope of comparative phylogenetic analysis of strain variability in detail. Nevertheless, the study highlights the importance of rendering protection to native cultured fish by preventing their introduction and further spread on a local or national scale to either known or unknown susceptible fish species available in the region, and emphasize upon strengthening surveillance system.

Strain variability of foodborne pathogens in microbiological risk assessment - a review

Strain variability is one of the most important factors to influence the accuracy of foodborne pathogens risk assessment, such as Listeria monocytogenes, Salmonella spp. Strain-to-strain variation is defined as the inherent differences among identically treated strains of the same microbial species. The differences cannot be eliminated by changing test methods or improving test protocols. This review addresses presently related studies of strain variability. Based on the effect of strain variability on the outcome of risk assessment, we summarize sources of variabilities in food chain, strain phenotypic variabilities and the methods to integrate strain variability in growth and inactivation into predictive modelling, and indicate the inadequacies in the study of strain variability. We suggest further study the mechanism of strain variability, expand the comparison of variability among different sources, and integrate the variability of gene expression, protein and cell metabolism into the predictive modelling.

Studies in bank voles reveal strain differences between chronic wasting disease prions from Norway and North America

Chronic wasting disease (CWD) is a relentless epidemic disorder caused by infectious prions that threatens the survival of cervid populations and raises increasing public health concerns in North America. In Europe, CWD was detected for the first time in wild Norwegian reindeer (Rangifer tarandus) and moose (Alces alces) in 2016. In this study, we aimed at comparing the strain properties of CWD prions derived from different cervid species in Norway and North America. Using a classical strain typing approach involving transmission and adaptation to bank voles (Myodes glareolus), we found that prions causing CWD in Norway induced incubation times, neuropathology, regional deposition of misfolded prion protein aggregates in the brain, and size of their protease-resistant core, different from those that characterize North American CWD. These findings show that CWD prion strains affecting Norwegian cervids are distinct from those found in North America, implying that the highly contagious North American CWD prions are not the proximate cause of the newly discovered Norwegian CWD cases. In addition, Norwegian CWD isolates showed an unexpected strain variability, with reindeer and moose being caused by different CWD strains. Our findings shed light on the origin of emergent European CWD, have significant implications for understanding the nature and the ecology of CWD in Europe, and highlight the need to assess the zoonotic potential of the new CWD strains detected in Europe.

Characterization of Clinical and Carrier Streptococcus agalactiae and Prophage Contribution to the Strain Variability.

Streptococcus agalactiae (group B Streptococcus, GBS) represents a leading cause of invasive bacterial infections in newborns and is also responsible for diseases in older and immunocompromised adults. Prophages represent an important factor contributing to the genome plasticity and evolution of new strains. In the present study, prophage content was analyzed in human GBS isolates. Thirty-seven prophages were identified in genomes of 20 representative sequenced strains. On the basis of the sequence comparison, we divided the prophages into eight groups named A–H. This division also corresponded to the clustering of phage integrase, even though several different integration sites were observed in some relative prophages. Next, PCR method was used for detection of the prophages in 123 GBS strains from adult hospitalized patients and from pregnancy screening. At least one prophage was present in 105 isolates (85%). The highest prevalence was observed for prophage group A (71%) and satellite prophage group B (62%). Other groups were detected infrequently (1–6%). Prophage distribution did not differ between clinical and screening strains, but it was unevenly distributed in MLST (multi locus sequence typing) sequence types. High content of full-length and satellite prophages detected in present study implies that prophages could be beneficial for the host bacterium and could contribute to evolution of more adapted strains.