scholarly journals Opacity-Associated Adhesin Repertoire in Hyperinvasive Neisseria meningitidis

2006 ◽  
Vol 74 (9) ◽  
pp. 5085-5094 ◽  
Author(s):  
Martin J. Callaghan ◽  
Keith A. Jolley ◽  
Martin C. J. Maiden
Keyword(s):  
Genetic Diversity ◽  
Neisseria Meningitidis ◽  
Meningococcal Disease ◽  
Sequence Diversity ◽  
Central Importance ◽  
Global Spread ◽  
Time Periods ◽  
High Level ◽  
Protein Variants ◽  
Over Time

ABSTRACT The opacity (Opa) proteins mediate a variety of interactions between the bacterium Neisseria meningitidis and its human host. These interactions are thought to be of central importance in both the asymptomatic colonization of the nasopharynx and the sporadic occurrence of meningococcal disease. The receptor specificities of a limited number of Opa protein variants have been explored, but the high level of amino acid sequence diversity among variants has complicated the assignment of specific roles to individual Opa variants or combinations of variants. In addition, the distribution of Opa protein variants among diverse meningococci, information that is potentially informative for studies of Opa function, is poorly understood. A systematic survey of the genetic diversity in the four opa gene loci in each of 77 meningococcal isolates was undertaken. These isolates were representative of the seven hyperinvasive meningococcal clonal complexes that caused the majority of meningococcal disease over the last 50 years. Consistent with previous studies, a high level of sequence diversity was observed among the opa genes and the proteins that they encoded; however, particular sets of Opa protein variants were consistently associated with each of the clonal complexes over time periods often spanning decades and during global spread. These observations were consistent with the postulate that particular combinations of Opa proteins confer fitness advantages to individual clonal complexes and have implications for studies of Opa function and the inclusion of Opa proteins in novel meningococcal vaccines.

Prevalence and genetic diversity of two adhesion-related genes, pilE and nadA, in Neisseria meningitidis in China

2013 ◽  
Vol 141 (10) ◽  
pp. 2163-2172 ◽  
Author(s):  
X. SUN ◽  
H. ZHOU ◽  
L. XU ◽  
H. YANG ◽  
Y. GAO ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Neisseria Meningitidis ◽  
Adhesion Molecules ◽  
Meningococcal Disease ◽  
Class Ii ◽  
Type Iv Pili ◽  
Invasive Meningococcal Disease ◽  
Class I ◽  
Type Iv

SUMMARYThe main Neisseria meningitidis adhesion molecules, type IV pili (Tfp) and Neisseria adhesion A (NadA), play important roles in the pathogenesis of invasive meningococcal disease. PilE is the major Tfp subunit. In this study, the prevalence and genetic diversity of pilE and nadA were investigated in the prevalent serogroups and clonal complexes (CC) of N. meningitidis isolated in China. All serogroup A strains belonging to CC1 and CC5 and all CC11 serogroup W135 strains were clustered into class II PilE clades. All serogroup C and most of serogroup B isolates except CC8 and ST5642 were class I PilE clades. Class II pilE sequences were highly conserved. All isolates belonging to class I PilE isolates were nadA negative. However, nadA-positive strains were exclusively found in CC5 and CC11 isolates (class II PilE). This study showed that PilE and NadA may be related to epidemic or endemic meningococcal disease.

scholarly journals PorA Variable Antigenic Regions VR1, VR2, and VR3 of Neisseria meningitidis Serogroups B and C Isolated in Brazil from 1999 to 2004

2007 ◽  
Vol 75 (7) ◽  
pp. 3683-3685 ◽  
Author(s):  
Ivano de Filippis ◽  
Claudia Ferreira de Andrade ◽  
Luciete Silva ◽  
D. Rebecca Prevots ◽  
Ana Carolina P. Vicente
Keyword(s):  
Genetic Diversity ◽  
Neisseria Meningitidis ◽  
Meningococcal Disease ◽  
High Genetic Diversity ◽  
Epitope Variant ◽  
The Stability ◽  
Healthy Carriers ◽  
Antigenic Regions

ABSTRACT The high genetic diversity found among the PorA regions VR1 and VR2 of 101 Neisseria meningitidis isolates from patients with meningococcal disease and healthy carriers in Brazil contrasts with the stability found in the PorA VR3 of these isolates. The presence of VR3 epitope variant 35 or 36 on the surfaces of 87% of the strains analyzed suggests that these antigens should be considered for inclusion in new formulations of vaccines against serogroup B meningococci in Brazil.

scholarly journals Influence of the combination and phase variation status of the haemoglobin receptors HmbR and HpuAB on meningococcal virulence

Microbiology ◽  
2011 ◽  
Vol 157 (5) ◽  
pp. 1446-1456 ◽  
Author(s):  
Isfahan Tauseef ◽  
Odile B. Harrison ◽  
Karl G. Wooldridge ◽  
Ian M. Feavers ◽  
Keith R. Neal ◽  
...  
Keyword(s):  
Neisseria Meningitidis ◽  
Meningococcal Disease ◽  
Systemic Disease ◽  
Phase Variation ◽  
Phase Variable ◽  
Insertion Element ◽  
Systemic Spread ◽  
High Level ◽  
Complete Deletion

Neisseria meningitidis can utilize haem, haemoglobin and haemoglobin–haptoglobin complexes as sources of iron via two TonB-dependent phase variable haemoglobin receptors, HmbR and HpuAB. HmbR is over-represented in disease isolates, suggesting a link between haemoglobin acquisition and meningococcal disease. This study compared the distribution of HpuAB and phase variation (PV) status of both receptors in disease and carriage isolates. Meningococcal disease (n = 214) and carriage (n = 305) isolates representative of multiple clonal complexes (CCs) were investigated for the distribution, polyG tract lengths and ON/OFF status of both haemoglobin receptors, and for the deletion mechanism for HpuAB. Strains with both receptors or only hmbR were present at similar frequencies among meningococcal disease isolates as compared with carriage isolates. However, >90 % of isolates from the three CCs CC5, CC8 and CC11 with the highest disease to carriage ratios contained both receptors. Strains with an hpuAB-only phenotype were under-represented among disease isolates, suggesting selection against this receptor during systemic disease, possibly due to the receptor having a high level of immunogenicity or being inefficient in acquisition of iron during systemic spread. Absence of hpuAB resulted from either complete deletion or replacement by an insertion element. In an examination of PV status, one or both receptors were found in an ON state in 91 % of disease and 71 % of carriage isolates. We suggest that expression of a haemoglobin receptor, either HmbR or HpuAB, is of major importance for systemic spread of meningococci, and that the presence of both receptors contributes to virulence in some strains.

The panmictic nature ofNeisseria meningitidisserogroup B during a period of endemic disease in Canada

2001 ◽  
Vol 47 (4) ◽  
pp. 283-289 ◽  
Author(s):  
Fraser E Ashton ◽  
Dominique A Caugant
Keyword(s):  
Genetic Diversity ◽  
Cluster Analysis ◽  
Neisseria Meningitidis ◽  
Meningococcal Disease ◽  
Enzyme Electrophoresis ◽  
Endemic Disease ◽  
Multilocus Enzyme Electrophoresis ◽  
Common Serotypes ◽  
The Mean ◽  
Group B

Three hundred and one (301) strains of Neisseria meningitidis serogroup B, isolated from patients with meningococcal disease during the years 1994–1996, were subjected to multilocus enzyme electrophoresis, serotyping, and serosubtyping. Based on the analyses of 14 enzyme loci, 177 electrophoretic types (ETs) were identified. Of these, 136 were represented by single isolates and 41 were represented by multiple isolates (range 2–31). The mean genetic diversity for isolates was 0.444 and for ETs was 0.440. The index of association (IA) between loci was 0.530 ± 0.08 for isolates and 0.256 ± 0.10 for ETs. Cluster analysis revealed the presence of 39 lineages each represented by a single ET or clusters of ETs. The most common serotypes were 4, 15, and 14 and accounted for 84 (28.0%), 53 (17.6%), and 32 (10.6%) of the isolates, respectively, and were dispersed amongst 46 ETs (1–122), 35 ETs (3–165), and 26 ETs (18–76), respectively. The 109 (36.6%) nontypable (NT) isolates were amongst 74 ETs (6–177). The mean genetic diversity for serotypes 4, 15, and 14 and NT isolates was 0.368, 0.371, 0.343, and 0.442, respectively, and for ETs was 0.363, 0.354, 0.397, and 0.440, respectively. Combinations of serotypes and serosubtypes (number of isolates) that occurred most frequently were 4:P1.14 (17), 14:P1.16 (16), NT:P1.16 (16), 15:P1.16 (13), and NT:P1.13 (13). The majority of group B disease in Canada during 1994–1996 was caused by meningococci of considerable genetic diversity, and reflects a situation of endemic disease. However, the results also indicate that organisms belonging to the ET-5 complex, which has been responsible for outbreaks of group B disease globally for several decades, have been introduced into the country.Key words: meningococcal, genotypes, serotypes, serosubtypes, Neisseria meningitidis.

Thinning in mature eastern white pine: 43-year case study

2002 ◽  
Vol 78 (4) ◽  
pp. 539-549 ◽  
Author(s):  
Paul D Anderson ◽  
John C Zasada ◽  
Glen W Erickson ◽  
Zigmond A Zasada
Keyword(s):  
Genetic Diversity ◽  
Dna Analysis ◽  
Large Diameter ◽  
White Pine ◽  
Thinning Intensity ◽  
Pine Regeneration ◽  
Volume Production ◽  
Pine Stands ◽  
Over Time

A white pine (Pinus strobus L.) stand at the western margin of the species range, approximately 125 years of age at present, was thinned in 1953 from 33.5 m2 ha-1 to target residual basal areas of 18.4, 23.0, 27.5, and 32.1 m2 ha-1 . Repeated measurement over the following 43-years indicated that the greatest total volume production and the greatest number of large diameter trees occurred in the unit of highest residual density. Over time, the distribution of stems was predominantly random although mortality between 1979 and 1996 resulted in a tendency for clumping in the 23.0 and 27.5 m2 ha-1 treatments. DNA analysis indicated that thinning intensity had little effect on the genetic diversity of residual white pine. This study suggests that mature white pine stands in northern Minnesota may be managed at relatively high densities without loss of productivity. However, regardless of overstory density, there was little or no white pine regeneration occurring in this stand. Key words: thinning, growth, genetic diversity, molecular markers, spatial pattern, regeneration

scholarly journals Structured and Systematic Team and Procedure Training in Severe Trauma: Going from ‘Zero to Hero’ for a Time-Critical, Low-Volume Emergency Procedure Over Three Time Periods

2021 ◽  
Vol 45 (5) ◽  
pp. 1340-1348
Author(s):  
Maryam Meshkinfamfard ◽  
Jon Kristian Narvestad ◽  
Johannes Wiik Larsen ◽  
Arezo Kanani ◽  
Jørgen Vennesland ◽  
...  
Keyword(s):  
Injury Severity ◽  
Trauma System ◽  
Severe Trauma ◽  
Emergency Procedure ◽  
Emergency Thoracotomy ◽  
Severity Scores ◽  
Time Periods ◽  
Low Volume ◽  
Time Critical ◽  
Over Time

Abstract Background Resuscitative emergency thoracotomy is a potential life-saving procedure but is rarely performed outside of busy trauma centers. Yet the intervention cannot be deferred nor centralized for critically injured patients presenting in extremis. Low-volume experience may be mitigated by structured training. The aim of this study was to describe concurrent development of training and simulation in a trauma system and associated effect on one time-critical emergency procedure on patient outcome. Methods An observational cohort study split into 3 arbitrary time-phases of trauma system development referred to as ‘early’, ‘developing’ and ‘mature’ time-periods. Core characteristics of the system is described for each phase and concurrent outcomes for all consecutive emergency thoracotomies described with focus on patient characteristics and outcome analyzed for trends in time. Results Over the study period, a total of 36 emergency thoracotomies were performed, of which 5 survived (13.9%). The “early” phase had no survivors (0/10), with 2 of 13 (15%) and 3 of 13 (23%) surviving in the development and mature phase, respectively. A decline in ‘elderly’ (>55 years) patients who had emergency thoracotomy occurred with each time period (from 50%, 31% to 7.7%, respectively). The gender distribution and the injury severity scores on admission remained unchanged, while the rate of patients with signs on life (SOL) increased over time. Conclusion The improvement over time in survival for one time-critical emergency procedure may be attributed to structured implementation of team and procedure training. The findings may be transferred to other low-volume regions for improved trauma care.

Assessment of genetic variability amongst cultivated populations of Khasi mandarin (Citrus reticulata Blanco) detected by ISSR

2021 ◽  
pp. 1-11
Author(s):  
Karishma Kashyap ◽  
Rasika M. Bhagwat ◽  
Sofia Banu
Keyword(s):  
Genetic Diversity ◽  
Genetic Variability ◽  
Inter Simple Sequence Repeat ◽  
Northeast India ◽  
Issr Markers ◽  
Citrus Reticulata ◽  
Brahmaputra Valley ◽  
Indian Food ◽  
Cultivated Populations ◽  
High Level

Abstract Khasi mandarin (Citrus reticulata Blanco) is a commercial mandarin variety grown in northeast India and one of the 175 Indian food items included in the global first food atlas. The cultivated plantations of Khasi mandarin grown prominently in the lower Brahmaputra valley of Assam, northeast India, have been genetically eroded. The lack in the efforts for conservation of genetic variability in this mandarin variety prompted diversity analysis of Khasi mandarin germplasm across the region. Thus, the study aimed to investigate genetic diversity and partitioning of the genetic variations within and among 92 populations of Khasi mandarin collected from 10 cultivated sites in Kamrup and Kamrup (M) districts of Assam, India, using Inter-Simple Sequence Repeat (ISSR) markers. The amplification of genomic DNA with 17 ISSR primers yielded 216 scorable DNA amplicons of which 177 (81.94%) were polymorphic. The average polymorphism information content was 0.39 per primer. The total genetic diversity (HT = 0.28 ± 0.03) was close to the diversity within the population (HS = 0.20 ± 0.01). A high mean coefficient of gene differentiation (GST = 0.29) reflected a high level of gene flow (Nm = 1.22), indicating high genetic differentiation among the populations. Analysis of Molecular Variance (AMOVA) showed 78% of intra-population differentiation, 21% among the population and 1% among the districts. The obtained results indicate the existence of a high level of genetic diversity in the cultivated Khasi mandarin populations, indicating the need for preservation of each existing population to revive the dying out orchards in northeast India.

scholarly journals Molecular analysis of genetic diversity in population of Silybum marianum (L.) Gaertn in Egypt

2019 ◽  
Vol 17 (1) ◽  
Author(s):  
Marwa Hamouda
Keyword(s):  
Genetic Diversity ◽  
Electrophoretic Pattern ◽  
Issr Markers ◽  
Silybum Marianum ◽  
Inter Simple Sequence Repeats ◽  
Sds Page ◽  
Dna Pattern ◽  
Pharmaceutical Properties ◽  
High Level ◽  
Rapd And Issr

Abstract Background Silybum marianum L. Gaertn is a medicinal plant of unique pharmaceutical properties in the treatment of liver disorders and diabetic nephropathy. Biochemical (SDS-PAGE) and molecular markers such as randomly amplified polymorphic DNA (RAPD) and inter-simple sequence repeats (ISSR) technologies were used in this work to detect genetic diversity of 14 collections of Silybum marianum population in Egypt. Results The electrophoretic pattern of seed protein gave different molecular weight bands, ranging from 24 to 111 KDa with the presence of unique bands. RAPD results revealed a high level of polymorphism (73.2%) using 12 RAPD primers, but only eight of them gave reproducible polymorphic DNA pattern. Sixteen primers were used in the ISSR method; only ten of them yielded clearly identifiable bands. The percentage of polymorphism is about 80% of the studied samples. Conclusion The obtained data confirmed that SDS-protein, RAPD, and ISSR markers are important tools for genetic analysis for Silybum marianum and recommended to give accurate results.

scholarly journals Longitudinal assessment of the bovine ocular bacterial community dynamics in calves

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Alison C. Bartenslager ◽  
Nirosh D. Althuge ◽  
John Dustin Loy ◽  
Matthew M. Hille ◽  
Matthew L. Spangler ◽  
...  
Keyword(s):  
Bacterial Community ◽  
Community Composition ◽  
Community Dynamics ◽  
Bacterial Community Composition ◽  
Clinical Signs ◽  
Sampling Time ◽  
Experimental Population ◽  
Opportunistic Pathogens ◽  
Time Periods ◽  
Over Time

Abstract Background Infectious Bovine Keratoconjunctivitis (IBK), commonly known as pinkeye, is one of the most significant diseases of beef cattle. As such, IBK costs the US beef industry at least 150 million annually. However, strategies to prevent IBK are limited, with most cases resulting in treatment with antibiotics once the disease has developed. Longitudinal studies evaluating establishment of the ocular microbiota may identify critical risk periods for IBK outbreaks or changes in the microbiota that may predispose animals to IBK. Results In an attempt to characterize the establishment and colonization patterns of the bovine ocular microbiota, we conducted a longitudinal study consisting of 227 calves and evaluated the microbiota composition over time using amplicon sequence variants (ASVs) based on 16S rRNA sequencing data and culture-based approaches. Beef calves on trial consisted of both male (intact) and females. Breeds were composed of purebred Angus and composites with varying percentages of Simmental, Angus, and Red Angus breeds. Average age at the start of the trial was 65 days ±15.02 and all calves remained nursing on their dam until weaning (day 139 of the study). The trial consisted of 139 days with four sampling time points on day 0, 21, 41, and 139. The experimental population received three different vaccination treatments (autogenous, commercial (both inactivated bacteria), and adjuvant placebo), to assess the effectiveness of different vaccines for IBK prevention. A significant change in bacterial community composition was observed across time periods sampled compared to the baseline (p < 0.001). However, no treatment effect of vaccine was detected within the ocular bacterial community. The bacterial community composition with the greatest time span between sampling time periods (98d span) was most similar to the baseline sample collected, suggesting re-establishment of the ocular microbiota to baseline levels over time after perturbation. The effect of IgA levels on the microbial community was investigated in a subset of cattle within the study. However, no significant effect of IgA was observed. Significant changes in the ocular microbiota were identified when comparing communities pre- and post-clinical signs of IBK. Additionally, dynamic changes in opportunistic pathogens Moraxella spp. were observed and confirmed using culture based methods. Conclusions Our results indicate that the bovine ocular microbiota is well represented by opportunistic pathogens such as Moraxella and Mycoplasma. Furthermore, this study characterizes the diversity of the ocular microbiota in calves and demonstrates the plasticity of the ocular microbiota to change. Additionally, we demonstrate the ocular microbiome in calves is similar between the eyes and the perturbation of one eye results in similar changes in the other eye. We also demonstrate the bovine ocular microbiota is slow to recover post perturbation and as a result provide opportunistic pathogens a chance to establish within the eye leading to IBK and other diseases. Characterizing the dynamic nature of the ocular microbiota provides novel opportunities to develop potential probiotic intervention to reduce IBK outbreaks in cattle.

scholarly journals Effect of Ionizing Radiation on the Bacterial and Fungal Endophytes of the Halophytic Plant Kalidium schrenkianum

2021 ◽  
Vol 9 (5) ◽  
pp. 1050
Author(s):  
Jing Zhu ◽  
Xiang Sun ◽  
Zhi-Dong Zhang ◽  
Qi-Yong Tang ◽  
Mei-Ying Gu ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Ionizing Radiation ◽  
Endophytic Bacteria ◽  
Fungal Endophytes ◽  
Root Endophytes ◽  
Fungal Community Structure ◽  
Geochemical Factors ◽  
Bacteria And Fungi ◽  
High Level ◽  
And Control

Endophytic bacteria and fungi colonize plants that grow in various types of terrestrial and aquatic ecosystems. Our study investigates the communities of endophytic bacteria and fungi of halophyte Kalidium schrenkianum growing in stressed habitats with ionizing radiation. The geochemical factors and radiation (at low, medium, high level and control) both affected the structure of endophytic communities. The bacterial class Actinobacteria and the fungal class Dothideomycetes predominated the endophytic communities of K. schrenkianum. Aerial tissues of K. schrenkianum had higher fungal diversity, while roots had higher bacterial diversity. Radiation had no significant effect on the abundance of bacterial classes. Soil pH, total nitrogen, and organic matter showed significant effects on the diversity of root endophytes. Radiation affected bacterial and fungal community structure in roots but not in aerial tissues, and had a strong effect on fungal co-occurrence networks. Overall, the genetic diversity of both endophytic bacteria and fungi was higher in radioactive environments, however negative correlations were found between endophytic bacteria and fungi in the plant. The genetic diversity of both endophytic bacteria and fungi was higher in radioactive environments. Our findings suggest that radiation affects root endophytes, and that the endophytes associated with aerial tissues and roots of K. schrenkianum follow different mechanisms for community assembly and different paradigms in stress response.

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