71 research outputs found
Humane neutrophile Granulozyten töten B. anthracis mit einem α-Defensin abhängigen Mechanismus
Deckblatt - Impressum
Zitat
Table of contents
Abbreviations
Introduction
Literature survey
Materials and Methods
Results
Discussion
Summary
References
Zusammenfassung
Acknowledgment
SelbständigkeitserklärungThe environmentally highly resistant B. anthracis spores cause natural
infections in man and animals but have also been used as biological weapons.
B. anthracis infection begins through intradermal inoculation, ingestion or
inhalation of spores. Human pulmonary and gastric infections with Bacillus
anthracis are almost always lethal, yet cutaneous infections usually remain
localized and resolve spontaneously. Interestingly neutrophils are recruited
to cutaneous but not other forms of B. anthracis infections, raising the
possibility that neutrophils kill B. anthracis. Neutrophils are the first
cells of the innate immune system, which are recruited to a site of infection.
Other cells of the innate immune system such as macrophages and dendritic
cells have been implicated in the dissemination of B. anthracis and in the
pathology of the infection, but not in its resolution. The role neutrophils
play in B. anthracis infection has not been extensively studied. B. anthracis
is characterized by its two virulence plasmids encoding the two major
virulence factors: the tripartite anthrax toxin and the poly-D-glutamate
capsule. The toxin induces oedema and shock-like symptoms; the capsule was
reported to have antiphagocytic properties. In this study we infected human
neutrophils with B. anthracis spores or vegetative bacteria expressing either
of the two major virulence factors. As studied by electron microscopy, human
neutrophils engulfed B. anthracis spores, which germinated intracellularly and
were then killed. The killing of vegetative bacteria either expressing the
toxin or the capsule was also examined. Both B. anthracis strains were
phagocytosed and efficiently killed. Through inhibition of neutrophil
phagocytosis with cytochalsin D we showed that the killing mechanism was of
both intracellular and extracellular nature. Further, the killing of the
vegetative cells was not due to reactive oxygen species but a result of the
activity of a human neutrophil granule extract. This was elucidated by the use
of an inhibitor of ROS production. We fractionated the neutrophil granule
extract (hNGE) by high performance liquid chromatography with a combination of
C4/ C4/ C18 reverse phase columns. -defensins were identified by MALDI TOF
TOF analysis as the component responsible for B. anthracis killing.
-defensins are constituents of the neutrophil azurophil granules, which have
also been implicated in the neutralization of the anthrax toxin. These data
show that human neutrophils induce germination of B. anthracis spores and
consequently kill the vegetative cells. This and the pathohistology of human
anthrax cases suggest that the timely recruitment of neutrophils in the human
cutaneous form of the disease can control B. anthracis infections. This is
supported by the fact that pulmonary infections in pigs and dogs show massive
neutrophil infiltration, resulting in survival of the host.B. anthracis infiziert seinen Wirt durch intradermale sowie orale Aufnahme
oder durch Inhalation von Sporen. Humane pulmonale und gastrointestinale
Verlaufsformen weisen eine sehr hohe Mortalität auf. Im Gegensatz dazu ruft
die dermale Form lokale Hautveränderungen hervor und heilt in 90% aller Fälle
spontan. Interessanterweise werden bei der dermalen Form neutrophile
Granulozyten an den Infektionsherd rekrutiert, während diese Infiltration in
den zwei anderen klinischen Formen selten beschrieben wird. Dies eröffnet die
Frage ob neutrophile Granulozyten B. anthracis töten und dadurch eine
ungeahnte und drastische Auswirkung auf das Krankheitsgeschehen haben können.
Während dieser Studie wurden neutrophile Granulozyten mit entweder B.
anthracis Sporen oder vegetativen Bakterien infiziert, die einen der beiden
Hauptvirulenzfaktoren exprimieren. Die humanen neutrophilen Granulozyten
phagozytieren die B. anthracis Sporen, diese germinieren intrazellulär und
werden von den neutrophilen Granulozyten getötet. Die Interaktion neutrophiler
Granulozyten mit toxin- oder kapselproduzierenden vegetativen Bakterien wurde
auch untersucht. Beide Stämme werden phagozytiert und effizient getötet. Der
Tötungsmechanismus ist unabhängig von reaktiven Sauerstoffspezies, aber
abhängig von einem aus humanen neutrophilen Granulozyten gewonnenem
Granulaextrakt. Das Extrakt wurde mit High Performance Liquid Chromatography
(HPLC) fraktioniert und α-Defensine als eine der zuständigen anti-B. anthracis
Komponenten identifiziert. Unsere Daten, im Zusammenhang mit der
Pathohistologie humaner Milzbrandfälle, implizieren, dass die rechtzeitige
Einwanderung neutrophiler Granulozyten während des kutanen Milzbrand zur
lokalen Eindämmung dieser Infektion führt. Diese These wird durch den Umstand
unterstĂĽtzt, dass die pulmonale Form bei Hunden und Schweinen mit massiver
neutrophiler Granulozyteninfiltration einhergeht, welches zum Ăśberleben dieser
Wirte fĂĽhrt
Distribution of Leptospira Serogroups in Dogs from Berlin, Germany
Leptospirosis is a bacterial zoonosis in which dogs can act as a reservoir for
human infection. The annual vaccination of dogs can prevent leptospirosis
caused by serovars included in the vaccine. To date, all available vaccines in
Germany include only the serovars Icterohaemorrhagiae and Canicola, the most
commonly found serovars prior to the introduction of the leptospirosis
vaccines. Yet, the involvement of additional serovars in the clinical
presentation of leptospirosis in dogs has been described. The objective of
this sero-epidemiological study was to examine the different Leptospira
serovars currently circulating in a population of dogs suspicious for
leptospirosis from Berlin. In 329 dogs presenting at the Small Animal Clinic
in Berlin, the predominant serogroup was Australis (24%), followed by
Grippotyphosa (20%) and Pomona (9%). A total of 18% of the dogs were diagnosed
with clinical leptospirosis; here the most prevalent serogroups were also
Australis (28%), Grippotyphosa (18%), and Pomona (14%). The serovar prevalence
data presented here confirm that a change of pattern of infecting Leptospira
serovars in dogs has taken place in Berlin. This data corresponds to further
sero-epidemiological studies from other regions in Germany. To ensure human
and canine health, available vaccines should be adapted to include the most
important circulating serovars
Re-emerging Trichinella seroprevalence in Ban pigs raised by ethnic minorities of Hoa Binh province
Rapid Identification of the Foodborne Pathogen Trichinella spp. by Matrix- Assisted Laser Desorption/Ionization Mass Spectrometry
Human trichinellosis occurs through consumption of raw or inadequately
processed meat or meat products containing larvae of the parasitic nematodes
of the genus Trichinella. Currently, nine species and three genotypes are
recognized, of which T. spiralis, T. britovi and T. pseudospiralis have the
highest public health relevance. To date, the differentiation of the larvae to
the species and genotype level is based primarily on molecular methods, which
can be relatively time consuming and labor intensive. Due to its rapidness and
ease of use a matrix assisted laser desorption / ionization time of flight
mass spectrometry (MALDI-TOF MS) reference spectra database using Trichinella
strains of all known species and genotypes was created. A
formicacid/acetonitrile protein extraction was carried out after pooling 10
larvae of each Trichinella species and genotype. Each sample was spotted 9
times using α-cyano 4-hydoxy cinnamic acid matrix and a MicroFlex LT mass
spectrometer was used to acquire 3 spectra (m/z 2000 to 20000 Da) from each
spot resulting in 27 spectra/species or genotype. Following the spectra
quality assessment, Biotyper software was used to create a main spectra
library (MSP) representing nine species and three genotypes of Trichinella.
The evaluation of the spectra generated by MALDI-TOF MS revealed a
classification which was comparable to the results obtained by molecular
methods. Also, each Trichinella species utilized in this study was distinct
and distinguishable with a high confidence level. Further, different
conservation methods such as freezing and conservation in alcohol and the host
species origin of the isolated larvae did not have a significant influence on
the generated spectra. Therefore, the described MALDI-TOF MS can successfully
be implemented for both genus and species level identification and represents
a major step forward in the use of this technique in foodborne parasitology
Serological prevalence and factors associated with human trichinellosis and cysticercosis in Hoa Binh Province, Northwest Vietnam
Longitudinal Study of Selected Bacterial Zoonoses in Small Ruminants in Tana River County, Kenya
Brucellosis, Q fever, and leptospirosis are priority zoonoses worldwide, yet their epidemiology is understudied, and studies investigating multiple pathogens are scarce. Therefore, we selected 316 small ruminants in irrigated, pastoral, and riverine settings in Tana River County and conducted repeated sampling for animals that were initially seronegative between September 2014 and June 2015. We carried out serological and polymerase chain reaction tests and determined risk factors for exposure. The survey-weighted serological incidence rates were 1.8 (95% confidence intervals [CI]: 1.3–2.5) and 1.3 (95% CI: 0.7–2.3) cases per 100 animal-months at risk for Leptospira spp. and C. burnetii, respectively. We observed no seroconversions for Brucella spp. Animals from the irrigated setting had 6.83 (95% CI: 2.58–18.06, p-value = 0.01) higher odds of seropositivity to C. burnetii than those from riverine settings. Considerable co-exposure of animals to more than one zoonosis was also observed, with animals exposed to one zoonosis generally having 2.5 times higher odds of exposure to a second zoonosis. The higher incidence of C. burnetii and Leptospira spp. infections, which are understudied zoonoses in Kenya compared to Brucella spp., demonstrate the need for systematic prioritization of animal diseases to enable the appropriate allocation of resources
A systematic review and meta-analysis of the aetiological agents of non-malarial febrile illnesses in Africa
BackgroundThe awareness of non-malarial febrile illnesses (NMFIs) has been on the rise over the last decades. Therefore, we undertook a systematic literature review and meta-analysis of causative agents of non-malarial fevers on the African continent.MethodologyWe searched for literature in African Journals Online, EMBASE, PubMed, Scopus, and Web of Science databases to identify aetiologic agents that had been reported and to determine summary estimates of the proportional morbidity rates (PMr) associated with these pathogens among fever patients.FindingsA total of 133 studies comprising 391,835 patients from 25 of the 54 African countries were eligible. A wide array of aetiologic agents were described with considerable regional differences among the leading agents. Overall, bacterial pathogens tested from blood samples accounted for the largest proportion. The summary estimates from the meta-analysis were low for most of the agents. This may have resulted from a true low prevalence of the agents, the failure to test for many agents or the low sensitivity of the diagnostic methods applied. Our meta-regression analysis of study and population variables showed that diagnostic methods determined the PMr estimates of typhoidal Salmonella and Dengue virus. An increase in the PMr of Klebsiella spp. infections was observed over time. Furthermore, the status of patients as either inpatient or outpatient predicted the PMr of Haemophilus spp. infections.ConclusionThe small number of epidemiological studies and the variety of NMFI agents on the African continent emphasizes the need for harmonized studies with larger sample sizes. In particular, diagnostic procedures for NMFIs should be standardized to facilitate comparability of study results and to improve future meta-analyses. Reliable NMFI burden estimates will inform regional public health strategies
Longitudinal Study of Selected Bacterial Zoonoses in Small Ruminants in Tana River County, Kenya
Brucellosis, Q fever, and leptospirosis are priority zoonoses worldwide, yet their epidemiology is understudied, and studies investigating multiple pathogens are scarce. Therefore, we selected 316 small ruminants in irrigated, pastoral, and riverine settings in Tana River County and conducted repeated sampling for animals that were initially seronegative between September 2014 and June 2015. We carried out serological and polymerase chain reaction tests and determined risk factors for exposure. The survey-weighted serological incidence rates were 1.8 (95% confidence intervals [CI]: 1.3-2.5) and 1.3 (95% CI: 0.7-2.3) cases per 100 animal-months at risk for Leptospira spp. and C. burnetii, respectively. We observed no seroconversions for Brucella spp. Animals from the irrigated setting had 6.83 (95% CI: 2.58-18.06, p-value = 0.01) higher odds of seropositivity to C. burnetii than those from riverine settings. Considerable co-exposure of animals to more than one zoonosis was also observed, with animals exposed to one zoonosis generally having 2.5 times higher odds of exposure to a second zoonosis. The higher incidence of C. burnetii and Leptospira spp. infections, which are understudied zoonoses in Kenya compared to Brucella spp., demonstrate the need for systematic prioritization of animal diseases to enable the appropriate allocation of resources
Surveillance of climate-sensitive zoonotic diseases: Leptospirosis at livestock slaughterhouses in three regions of Uganda
Leptospirosis is an important bacterial zoonosis worldwide and is disproportionately associated with low-income settings and with extreme weather events due to climate change.
Transmission to humans often occurs when infected rodents and domestic animals contaminate the environment via urine as the bacteria preferentially colonise kidneys. Surveillance
of leptospirosis at slaughterhouses can therefore be useful in providing information on vast
areas of a country and screening for diseases that are not considered during animal inspections.
We determined the prevalence of Leptospira bacteria in the kidneys of 2,030 livestock
kidney samples (820 cattle, 761 pigs, 335 goats, 114 sheep), and 117 small mammals by realtime PCR in a cross-sectional survey of slaughter facilities in three regions in Uganda. We
extracted DNA and performed real-time polymerase chain reaction (PCR) tests targeting
the lipL32 gene for pathogenic leptospires. Positive samples with cycle threshold values
below 38 were further characterised using single locus sequence typing (SLST) to determine
likely genomospecies. PCR products were sequenced by Eurofins Genomics (Ebersberg,
Germany) and identification of genomospecies was done using the basic local alignment
search tool (BLAST). Multi-locus sequencing typing (MLST) was performed on selected
SLST-positive samples to determine sequence types (ST) and likely serogroups. The allelic
profiles were analysed using Bionumerics software and the sequence types were determined
using the PubMLST database.
An overall prevalence of pathogenic leptospires of 2.58 % (95 % confidence intervals [CI]:
1.89–3.42) was observed, with sheep having the highest prevalence (6.12 % CI: 2.69–12.89),
followed by cattle (4.25 %, 95 % CI: 2.91–5.98), goats (2.08 %, 95 % CI=0.91–4.38), and pigs
(0.46 %, 95 % CI = 0.12–1.31) in decreasing order. The genomospecies L. borgpetersenii
(11 in cattle and one in goat), L. kirschneri (five in cattle and four in sheep) and L.
interrogans (one in a pig) were determined. Preliminary MLST results on one sample
reveal L. kirschneri ST62 which is related to serogroup Grippotyphosa.
Surveillance of important zoonoses using slaughterhouses as sentinels has the potential to
offer essential information on the epidemiology of important zoonotic diseases in Uganda
Genetic identification of Trichinella species found in wild carnivores from the territory of Kazakhstan
Trichinellosis, also called trichinosis, is a foodborne parasitic disease caused by eating raw or undercooked meat from animals infected with Trichinella spp. larvae and affects both animals and humans. Although on the territory of Kazakhstan, the species characteristics and prevalence of this helminth were studied back in the 90s, the data have not been updated since then. Given the above, our study was aimed at identifying Trichinella spp. using parasitological and molecular genetics methods. In our work, we studied 160 samples of muscle tissue of wild animals living in the natural zones of steppes and semi-deserts. Of the animals examined, 32 were positive for Trichinella spp., including 1 lynx (Lynx lynx), 17 wolves (Canis lupus), 11 foxes (Vulpes vulpes), 1 jackal (Canis aureus) and 2 corsac foxes (Vulpes corsac). Helminths were extracted using the digestion method. DNA was extracted using a Gene Jet commercial kit (Thermo Fisher Scientific, United Kingdom). For species identification a multiplex PCR, amplification of ESV, ITS1, and ITS2 genes regions was performed. After that, uniplex PCR was performed on the 5S rDNA and ITS1 genes region for sequencing analysis. The resulting sequences were subsequently used to construct a phylogenetic tree and the studied samples were identified as Trichinella nativa and Trichinella britovi. Thus, we can conclude that there is a circulation of two species of Trichinella in Kazakhstan, highlighting that constant control and monitoring of wild animals are necessary to prevent transmission and protect the health of people
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