20 research outputs found
The Prevalence of Coxiella burnetii in Hard Ticks in Europe and Their Role in Q Fever Transmission RevisitedâA Systematic Review
The zoonosis Q fever is caused by the obligate intracellular bacterium Coxiella burnetii.
Besides the main transmission route via inhalation of contaminated aerosols, ticks are
discussed as vectors since the first isolation of the pathogen from a Dermacentor
andersonii tick. The rare detection of C. burnetii in ticks and the difficult differentiation
of C. burnetii from Coxiella-like endosymbionts (CLEs) are questioning the relevance of
ticks in the epidemiology of Q fever. In this review, literature databases were systematically
searched for recent prevalence studies concerning C. burnetii in ticks in Europe and
experimental studies evaluating the vector competence of tick species. A total of 72
prevalence studies were included and evaluated regarding DNA detection methods and
collectionmethods, country, and tested tick species. Specimens ofmore than 25 different
tick species were collected in 23 European countries. Overall, an average prevalence of
4.8% was determined. However, in half of the studies, no Coxiella-DNA was detected. In
Southern European countries, a significantly higher prevalence was observed, possibly
related to the abundance of different tick species here, namely Hyalomma spp. and
Rhipicephalus spp. In comparison, a similar proportion of studies used ticks sampled by
flagging and dragging or tick collection from animals, under 30% of the total tick samples
derived from the latter. There was no significant difference in the various target genes
used for the molecular test. In most of the studies, no distinction was made between
C. burnetii and CLEs. The application of specific detection methods and the confirmation
of positive results are crucial to determine the role of ticks in Q fever transmission. Only
two studies were available, which assessed the vector competence of ticks for C. burnetii
in the last 20 years, demonstrating the need for further research
Uptake and fecal excretion of Coxiella burnetii by Ixodes ricinus and Dermacentor marginatus ticks
Background:
The bacterium Coxiella burnetii is the etiological agent of Q fever and is mainly transmitted via inhalation of infectious aerosols. DNA of C. burnetii is frequently detected in ticks, but the role of ticks as vectors in the epidemiology of this agent is still controversial. In this study, Ixodes ricinus and Dermacentor marginatus adults as well as I. ricinus nymphs were fed on blood spiked with C. burnetii in order to study the fate of the bacterium within putative tick vectors.
Methods:
Blood-feeding experiments were performed in vitro in silicone-membrane based feeding units. The uptake, fecal excretion and transstadial transmission of C. burnetii was examined by quantitative real-time PCR as well as cultivation of feces and crushed tick filtrates in L-929 mouse fibroblast cells and cell-free culture medium.
Results:
Ticks successfully fed in the feeding system with engorgement rates ranging from 29% (D. marginatus) to 64% (I. ricinus adults). Coxiella burnetii DNA was detected in the feces of both tick species during and after feeding on blood containing 105 or 106 genomic equivalents per ml blood (GE/ml), but not when fed on blood containing only 104 GE/ml. Isolation and cultivation demonstrated the infectivity of C. burnetii in shed feces. In 25% of the I. ricinus nymphs feeding on inoculated blood, a transstadial transmission to the adult stage was detected. Females that molted from nymphs fed on inoculated blood excreted C. burnetii of up to 106 genomic equivalents per mg of feces.
Conclusions:
These findings show that transstadial transmission of C. burnetii occurs in I. ricinus and confirm that I. ricinus is a potential vector for Q fever. Transmission from both tick species might occur by inhalation of feces containing high amounts of viable C. burnetii rather than via tick bites
Low Energy Electron Irradiation Is a Potent Alternative to Gamma Irradiation for the Inactivation of (CAR-)NK-92 Cells in ATMP Manufacturing
Background: With increasing clinical use of NK-92 cells and their CAR-modified
derivatives in cancer immunotherapy, there is a growing demand for efficient
production processes of these âoff-the-shelfâ therapeutics. In order to ensure safety
and prevent the occurrence of secondary tumors, (CAR-)NK-92 cell proliferation has to be
inactivated before transfusion. This is commonly achieved by gamma irradiation. Recently,
we showed proof of concept that low energy electron irradiation (LEEI) is a new method for
NK-92 inactivation. LEEI has several advantages over gamma irradiation, including a faster
reaction time, a more reproducible dose rate and much less requirements on radiation
shielding. Here, LEEI was further evaluated as a promising alternative to gamma irradiation
yielding cells with highly maintained cytotoxic effector function.
Methods: Effectiveness and efficiency of LEEI and gamma irradiation were analyzed using
NK-92 and CD123-directed CAR-NK-92 cells. LEE-irradiated cells were extensively
characterized and compared to gamma-irradiated cells via flow cytometry, cytotoxicity
assays, and comet assays, amongst others.
Results: Our results show that both irradiation methods caused a progressive decrease
in cell viability and are, therefore, suitable for inhibition of cell proliferation. Notably, the NKmediated
specific lysis of tumor cells was maintained at stable levels for three days postirradiation,
with a trend towards higher activities after LEEI treatment as compared to
gamma irradiation. Both gamma irradiation as well as LEEI led to substantial DNA damage
and an accumulation of irradiated cells in the G2/M cell cycle phases. In addition,
transcriptomic analysis of irradiated cells revealed approximately 12-fold more
differentially expressed genes two hours after gamma irradiation, compared to LEEI.
Analysis of surface molecules revealed an irradiation-induced decrease in surface
expression of CD56, but no changes in the levels of the activating receptors NKp46,
NKG2D, or NKp30.
Conclusions: The presented data show that LEEI inactivates (CAR-)NK-92 cells as
efficiently as gamma irradiation, but with less impact on the overall gene expression. Due
to logistic advantages, LEEI might provide a superior alternative for the manufacture of
(CAR-)NK-92 cells for clinical application
The Prevalence of Coxiella burnetii in Hard Ticks in Europe and Their Role in Q Fever Transmission RevisitedâA Systematic Review
The zoonosis Q fever is caused by the obligate intracellular bacterium Coxiella burnetii.
Besides the main transmission route via inhalation of contaminated aerosols, ticks are
discussed as vectors since the first isolation of the pathogen from a Dermacentor
andersonii tick. The rare detection of C. burnetii in ticks and the difficult differentiation
of C. burnetii from Coxiella-like endosymbionts (CLEs) are questioning the relevance of
ticks in the epidemiology of Q fever. In this review, literature databases were systematically
searched for recent prevalence studies concerning C. burnetii in ticks in Europe and
experimental studies evaluating the vector competence of tick species. A total of 72
prevalence studies were included and evaluated regarding DNA detection methods and
collectionmethods, country, and tested tick species. Specimens ofmore than 25 different
tick species were collected in 23 European countries. Overall, an average prevalence of
4.8% was determined. However, in half of the studies, no Coxiella-DNA was detected. In
Southern European countries, a significantly higher prevalence was observed, possibly
related to the abundance of different tick species here, namely Hyalomma spp. and
Rhipicephalus spp. In comparison, a similar proportion of studies used ticks sampled by
flagging and dragging or tick collection from animals, under 30% of the total tick samples
derived from the latter. There was no significant difference in the various target genes
used for the molecular test. In most of the studies, no distinction was made between
C. burnetii and CLEs. The application of specific detection methods and the confirmation
of positive results are crucial to determine the role of ticks in Q fever transmission. Only
two studies were available, which assessed the vector competence of ticks for C. burnetii
in the last 20 years, demonstrating the need for further research
The Prevalence of Coxiella burnetii in Hard Ticks in Europe and Their Role in Q Fever Transmission RevisitedâA Systematic Review
The zoonosis Q fever is caused by the obligate intracellular bacterium Coxiella burnetii.
Besides the main transmission route via inhalation of contaminated aerosols, ticks are
discussed as vectors since the first isolation of the pathogen from a Dermacentor
andersonii tick. The rare detection of C. burnetii in ticks and the difficult differentiation
of C. burnetii from Coxiella-like endosymbionts (CLEs) are questioning the relevance of
ticks in the epidemiology of Q fever. In this review, literature databases were systematically
searched for recent prevalence studies concerning C. burnetii in ticks in Europe and
experimental studies evaluating the vector competence of tick species. A total of 72
prevalence studies were included and evaluated regarding DNA detection methods and
collectionmethods, country, and tested tick species. Specimens ofmore than 25 different
tick species were collected in 23 European countries. Overall, an average prevalence of
4.8% was determined. However, in half of the studies, no Coxiella-DNA was detected. In
Southern European countries, a significantly higher prevalence was observed, possibly
related to the abundance of different tick species here, namely Hyalomma spp. and
Rhipicephalus spp. In comparison, a similar proportion of studies used ticks sampled by
flagging and dragging or tick collection from animals, under 30% of the total tick samples
derived from the latter. There was no significant difference in the various target genes
used for the molecular test. In most of the studies, no distinction was made between
C. burnetii and CLEs. The application of specific detection methods and the confirmation
of positive results are crucial to determine the role of ticks in Q fever transmission. Only
two studies were available, which assessed the vector competence of ticks for C. burnetii
in the last 20 years, demonstrating the need for further research
Physiological and genetic mechanisms underlying caste development, reproduction and division of labor in stingless bees
Investigations on physiological and molecular mechanisms underlying developmental and reproductive differentiation in social bees center on the question of how different patterns of larval nutrition can affect hormonal dynamics and how these drive differential gene expression. Differential expression analyses and the generation of AFLP markers now enable us to re-examine the question of genetic caste determination in the genus Melipona. The comparison of vitellogenin expression in three species of stingless bees suggests divergence in regulatory mechanisms that directly relate to the mode of worker reproduction. As in honey bees, this indicates alternative functions for vitellogenin in the life cycle of adult workers. The diversity in life histories and their associated specific physiologies make the stingless bees a rich resource for information on evolutionary trajectories that have generated phenotypic plasticity in social Hymenoptera
Antibody Responses in Humans Infected with Newly Emerging Strains of West Nile Virus in Europe
Abstract
Infection with West Nile Virus (WNV) affects an increasing number of countries worldwide. Although most human infections result in no or mild flu-like symptoms, the elderly and those with a weakened immune system are at higher risk for developing severe neurological disease. Since its introduction into North America in 1999, WNV has spread across the continental United States and caused annual outbreaks with a total of 36,000 documented clinical cases and 3c1,500 deaths. In recent years, outbreaks of neuroinvasive disease also have been reported in Europe. The WNV strains isolated during these outbreaks differ from those in North America, as sequencing has revealed that distinct phylogenetic lineages of WNV concurrently circulate in Europe, which has potential implications for the development of vaccines, therapeutics, and diagnostic tests. Here, we studied the human antibody response to European WNV strains responsible for outbreaks in Italy and Greece in 2010, caused by lineage 1 and 2 strains, respectively. The WNV structural proteins were expressed as a series of overlapping fragments fused to a carrier-protein, and binding of IgG in sera from infected persons was analyzed. The results demonstrate that, although the humoral immune response to WNV in humans is heterogeneous, several dominant peptides are recognized
Antibody responses in humans infected with newly emerging strains of West Nile Virus in Europe
Infection with West Nile Virus (WNV) affects an increasing number of countries worldwide. Although most human infections result in no or mild flu-like symptoms, the elderly and those with a weakened immune system are at higher risk for developing severe neurological disease. Since its introduction into North America in 1999, WNV has spread across the continental United States and caused annual outbreaks with a total of 36,000 documented clinical cases and ,1,500 deaths. In recent years, outbreaks of neuroinvasive disease also have been reported in Europe. The WNV strains isolated during these outbreaks differ from those in North America, as sequencing has revealed that distinct phylogenetic lineages of WNV concurrently circulate in Europe, which has potential implications for the development of vaccines, therapeutics, and diagnostic tests. Here, we studied the human antibody response to European WNV strains responsible for outbreaks in Italy and Greece in 2010, caused by lineage 1 and 2 strains, respectively. The WNV structural proteins were expressed as a series of overlapping fragments fused to a carrier-protein, and binding of IgG in sera from infected persons was analyzed. The results demonstrate that, although the humoral immune response to WNV in humans is heterogeneous, several dominant peptides are recognized
Selection and Validation of siRNAs Preventing Uptake and Replication of SARS-CoV-2
In 2019, the novel highly infectious severe acute respiratory syndrome coronavirus 2 (SARSCoV-
2) outbreak rapidly led to a global pandemic with more than 346 million confirmed cases
worldwide, resulting in 5.5 million associated deaths (January 2022). Entry of all SARS-CoV-2
variants is mediated by the cellular angisin-converting enzyme 2 (ACE2). The virus abundantly
replicates in the epithelia of the upper respiratory tract. Beyond vaccines for immunization,
there is an imminent need for novel treatment options in COVID-19 patients. So far, only a few
drugs have found their way into the clinics, often withmodest success. Specific gene silencing
based on small interfering RNA (siRNA) has emerged as a promising strategy for therapeutic
intervention, preventing/limiting SARS-CoV-2 entry into host cells or interfering with viral
replication. Here, we pursued both strategies. We designed and screened nine siRNAs
(siA1-9) targeting the viral entry receptor ACE2. SiA1, (siRNA against exon1 of ACE2 mRNA)
was most efficient, with up to 90% knockdown of the ACE2 mRNA and protein for at least six
days. In vitro, siA1 application was found to protect Vero E6 and Huh-7 cells from infectionwith
SARS-CoV-2 with an up to ~92% reduction of the viral burden indicating that the treatment
targets both the endosomal and the viral entry at the cytoplasmic membrane. Since the RNAencoded
genome makes SARS-CoV-2 vulnerable to RNA interference (RNAi), we designed
and analysed eight siRNAs (siV1-8) directly targeting the Orf1a/b region of the SARS-CoV-2
RNA genome, encoding for non-structural proteins (nsp). As a significant hallmark of this study,
we identified siV1 (siRNA against leader protein of SARS-CoV-2), which targets the nsp1-
encoding sequence (a.k.a. âhost shutoff factorâ) as particularly efficient. SiV1 inhibited SARSCoV-
2 replication in Vero E6 or Huh-7 cells by more than 99% or 97%, respectively. It neither
led to toxic effects nor induced type I or III interferon production. Of note, sequence analyses
revealed the target sequence of siV1 to be highly conserved in SARS-CoV-2 variants. Thus,
our results identify the direct targeting of the viral RNA genome (ORF1a/b) by siRNAs as highly
efficient and introduce siV1 as a particularly promising drug candidate for therapeutic
intervention