Public's perspective on COVID-19 adenovirus vector vaccines after thrombosis with thrombocytopenia syndrome (TTS) reports and associated regulatory actions: A cross-sectional study in six EU member states

Objective: In 2021, thrombosis with thrombocytopenia syndrome (TTS) was confirmed by the European Medicines Agency (EMA) as a rare side effect of the COVID-19 adenovirus vector vaccines Vaxzevria® and Jcovden®. This study aimed to describe the public's knowledge of TTS and how it affected the willingness to be vaccinated with COVID-19 vaccines and other vaccines in six European countries. Methods: From June to October of 2022, a multi-country cross-sectional online survey was conducted in Denmark, Greece, Latvia, Netherlands, Portugal, and Slovenia. The minimum target of participants to be recruited was based on the size of the country's population. The results were analysed descriptively. Results: In total, 3794 respondents were included in the analysis; across the six countries, 33.3 %–68.3 % reported being familiar with signs and symptoms of TTS, although 3.1–61.4 % of those were able to identify the symptoms correctly. The reported changes in willingness to be vaccinated against COVID-19 and with other vaccines varied per country. The largest reported change in the willingness to be vaccinated with Vaxzevria® and Jcovden® was observed in Denmark (61.2 %), while the willingness to be vaccinated with other COVID-19 vaccines changed most in Slovenia (30.4 %). The smallest decrease in willingness towards future vaccination against COVID-19 was reported in the Netherlands (20.9 %) contrasting with the largest decrease observed in Latvia (69.1 %). Conclusion: Knowledge about TTS seemed to have influenced the public's opinion in Europe resulting in less willingness to be vaccinated with Vaxzevria® and Jcovden®. Willingness for vaccination against COVID-19 with other vaccines and widespread use of vaccines to prevent other diseases also differed and seemed to be determined by the approaches taken by national health authorities when reacting to and communicating about COVID-19 vaccination risks. Further investigation of optimal risk communication strategies is warranted

When numbers become individuals: Improving the quality of behavioral animal experiments by mapping and incorporating inter-individuality in mice.

In preclinical experimental animal research, inter-individual variability in phenotypic response is a major source of within-group variability that may negatively affect the power of animal experiments and the reproducibility of their outcomes. Individual differences however are often not actively accounted for in the design of animal experiments. The importance of accounting for this variability has become especially acknowledged in animal models that study the underlying mechanisms and/or treatment of psychiatric diseases. In humans, the susceptibility to develop psychopathologies and the response to treatment is known to vary greatly between patients. Incorporating this variation in animal models may not only make these models more representative, but could also improve our understanding of the underlying mechanisms that are involved in this differential susceptibility. In the present thesis we focused on inter-individual variability in habituation of anxiety responses in mice. The overarching aim of the studies was twofold: To improve our understanding of this variability by mapping its expression on a behavioral and physiological level in three commonly used mouse inbred strains. And: to explore whether systematic incorporation of such inter-individual variability in the analysis and design of our experiments would affect the quality of our results. By applying a multidimensional, individual-based analysis approach we identified two behavioral response types which were displayed by individuals of all three inbred strains. We subsequently demonstrated how controlling for this type of variability may affect the quality of experimental results, and may facilitate a more comprehensive understanding of inter-individuality in anxiety responses in mice

When numbers become individuals: Improving the quality of behavioral animal experiments by mapping and incorporating inter-individuality in mice.

In preclinical experimental animal research, inter-individual variability in phenotypic response is a major source of within-group variability that may negatively affect the power of animal experiments and the reproducibility of their outcomes. Individual differences however are often not actively accounted for in the design of animal experiments. The importance of accounting for this variability has become especially acknowledged in animal models that study the underlying mechanisms and/or treatment of psychiatric diseases. In humans, the susceptibility to develop psychopathologies and the response to treatment is known to vary greatly between patients. Incorporating this variation in animal models may not only make these models more representative, but could also improve our understanding of the underlying mechanisms that are involved in this differential susceptibility. In the present thesis we focused on inter-individual variability in habituation of anxiety responses in mice. The overarching aim of the studies was twofold: To improve our understanding of this variability by mapping its expression on a behavioral and physiological level in three commonly used mouse inbred strains. And: to explore whether systematic incorporation of such inter-individual variability in the analysis and design of our experiments would affect the quality of our results. By applying a multidimensional, individual-based analysis approach we identified two behavioral response types which were displayed by individuals of all three inbred strains. We subsequently demonstrated how controlling for this type of variability may affect the quality of experimental results, and may facilitate a more comprehensive understanding of inter-individuality in anxiety responses in mice

Human operant learning under concurrent reinforcement of response variability

This study asked whether the concurrent reinforcement of behavioral variability facilitates learning to emit a difficult target response. Sixty students repeatedly pressed sequences of keys, with an originally infrequently occurring target sequence consistently being followed by positive feedback. Three conditions differed in the feedback given to non-target sequences: concurrent positive feedback presented contingent on response variability, positive feedback presented non-contingently, or no reinforcement for any non-target responses (control condition). Contrary to the result of analogous rat studies, if anything, the participants in the control condition more readily learned to emit the target sequence than did the subjects in each of the other two conditions. It is argued that these contradictory findings are primarily caused by procedural differences, such as differences in the density of the reinforcement schedule applied to non-target behavior, rather than reflecting a true species difference. (c) 2005 Elsevier Inc. All rights reserved

Experimental Chlamydia gallinacea infection in chickens does not protect against a subsequent experimental Chlamydia psittaci infection

Chlamydia psittaci was considered the predominant chlamydial species in poultry until Chlamydia gallinacea was discovered in 2009. C. psittaci is a zoonotic obligate intracellular bacterium reported in more than 465 bird species including poultry. In poultry, infections can result in asymptomatic disease, but also in more severe systemic illness. The zoonotic potential of C. gallinacea has yet to be proven. Infections in poultry appear to be asymptomatic and in recent prevalence studies C. gallinacea was the main chlamydial species found in chickens. The high prevalence of C. gallinacea resulted in the question if an infection with C. gallinacea might protect against an infection with C. psittaci. To investigate possible cross protection, chickens were inoculated with C. gallinacea NL_G47 and subsequently inoculated with either a different strain of C. gallinacea (NL_F725) or C. psittaci. Chickens that had not been pre-inoculated with C. gallinacea NL_G47 were used as a C. gallinacea or C. psittaci infection control. In the groups that were inoculated with C. psittaci, no difference in pharyngeal or cloacal shedding, or in tissue dissemination was observed between the control group and the pre-inoculated group. In the groups inoculated with C. gallinacea NL_F725, shedding in cloacal swabs and tissues dissemination was lower in the group pre-inoculated with C. gallinacea NL_G47. These results indicate previous exposure to C. gallinacea does not protect against an infection with C. psittaci, but might protect against a new infection of C. gallinacea

Incorporating inter-individual variability in experimental design improves the quality of results of animal experiments

Inter-individual variability in quantitative traits is believed to potentially inflate the quality of results in animal experimentation. Yet, to our knowledge this effect has not been empirically tested. Here we test whether inter-individual variability in emotional response within mouse inbred strains affects the outcome of a pharmacological experiment. Three mouse inbred strains (BALB/c, C57BL/6 and 129S2) were behaviorally characterized through repeated exposure to a mild aversive stimulus (modified Hole Board, five consecutive trials). A multivariate clustering procedure yielded two multidimensional response types which were displayed by individuals of all three strains. We show that systematic incorporation of these individual response types in the design of a pharmacological experiment produces different results from an experimental pool in which this variation was not accounted for. To our knowledge, this is the first study that empirically confirms that inter-individual variability affects the interpretation of behavioral phenotypes and may obscure experimental results in a pharmacological experiment

Experimental Chlamydia gallinacea infection in chickens does not protect against a subsequent experimental Chlamydia psittaci infection

Chlamydia psittaci was considered the predominant chlamydial species in poultry until Chlamydia gallinacea was discovered in 2009. C. psittaci is a zoonotic obligate intracellular bacterium reported in more than 465 bird species including poultry. In poultry, infections can result in asymptomatic disease, but also in more severe systemic illness. The zoonotic potential of C. gallinacea has yet to be proven. Infections in poultry appear to be asymptomatic and in recent prevalence studies C. gallinacea was the main chlamydial species found in chickens. The high prevalence of C. gallinacea resulted in the question if an infection with C. gallinacea might protect against an infection with C. psittaci. To investigate possible cross protection, chickens were inoculated with C. gallinacea NL_G47 and subsequently inoculated with either a different strain of C. gallinacea (NL_F725) or C. psittaci. Chickens that had not been pre-inoculated with C. gallinacea NL_G47 were used as a C. gallinacea or C. psittaci infection control. In the groups that were inoculated with C. psittaci, no difference in pharyngeal or cloacal shedding, or in tissue dissemination was observed between the control group and the pre-inoculated group. In the groups inoculated with C. gallinacea NL_F725, shedding in cloacal swabs and tissues dissemination was lower in the group pre-inoculated with C. gallinacea NL_G47. These results indicate previous exposure to C. gallinacea does not protect against an infection with C. psittaci, but might protect against a new infection of C. gallinacea

Pathogenicity of Chlamydia gallinacea in chickens after oral inoculation

Chlamydia gallinacea is a recently discovered and widespread obligate intracellular bacterium in chickens. In chickens, infections appear to be asymptomatic, but can result in reduced weight gain in broilers. Molecular typing revealed C. gallinacea is genetically diverse which might lead to differences in pathogenic potential between strains. However, studies about the pathogenesis of different C. gallinacea strains are still limited. In this study, the pathogenesis of C. gallinacea strain NL_G47 was investigated in three consecutive animal experiments. The first experiment served as a pilot in which a maximum culturable dose was administered orally to 13 chickens. Excretion of chlamydial DNA in cloacal swabs was measured during 11 days post infection, but no clinical signs were observed. The second and third experiment were a repetition of the first experiment, but now chickens were sacrificed at consecutive time points to investigate tissue dissemination of C. gallinacea. Again excretion of chlamydial DNA in cloacal swabs was detected and no clinical signs were observed in line with the results of the first experiment. PCR and immunohistochemistry of tissue samples revealed C. gallinacea infected the epithelium of the jejunum, ileum and caecum. Furthermore, C. gallinacea could be detected in macrophages in the lamina propria and in follicular dendritic cells (FDCs) of the B cell follicles in the caecal tonsil. Results of serology showed a systemic antibody response from day seven or eight and onward in all three experiments. The experiments with strain NL_G47 confirmed observations from field studies that C. gallinacea infection does not result in acute clinical disease and mainly resides in the epithelium of the gut. Whether the presence of C. gallinacea results in chronic persistent infections with long term and less obvious health effects in line with observations on other infections caused by Chlamydiae, needs further investigation

Proof of concept for multiplex detection of antibodies against Chlamydia species in chicken serum using a bead-based suspension array with peptides as antigens

Abstract The available differentiating tests for Chlamydia are based on detection of genetic material and only give information about the actual infection status, but reveal nothing of past infections. As the use of serological methods increases the window of detection, the goal of this study was to investigate if it is possible to develop a differentiating serological test for antibodies against Chlamydia species in chicken sera. Focus was on C. psittaci, C. gallinacea, and two closely related species, i.e. C. abortus and C. avium. To enable differentiating serology, a bead-based Luminex suspension array was constructed, using peptides as antigens, derived from known immunoreactive Chlamydia proteins. For the majority of these peptides, species-specific seroreactivity in mammalian sera has been reported in literature. The suspension array correctly identified antibodies against various Chlamydia species in sera from experimentally infected mice, and was also able to differentiate between antibodies against C. psittaci and C. gallinacea in sera from experimentally infected chickens. In field sera, signals were difficult to interpret as insufficient sera from experimentally infected chickens were available for evaluating the seroreactivity of all peptides. Nevertheless, results of the suspension array with field sera are supported by published data on the occurrence of C. gallinacea in Dutch layers, thereby demonstrating the proof of concept of multiplex serology for Chlamydial species in poultry