Q fever vaccine efficacy and occupational exposure risk in Queensland, Australia: A retrospective cohort study

Ultraviolet C inactivation of Coxiella burnetii for production of a structurally preserved whole cell vaccine antigen

Q fever, a worldwide-occurring zoonotic disease, can cause economic losses for public and veterinary health systems. Vaccines are not yet available worldwide and currently under development. In this regard, it is important to produce a whole cell antigen, with preserved structural and antigenic properties and free of chemical modifications. Thus, inactivation of Coxiella burnetii with ultraviolet light C (UVC) was evaluated. C. burnetii Nine Mile phase I (NMI) and phase II (NMII) were exposed to decreasing intensities in a time-dependent manner and viability was tested by rescue cultivation in axenic medium or cell culture. Effects on the cell structure were visualized by transmission electron microscopy and antigenicity of UVC-treated NMI was studied by immunization of rabbits. NMI and NMII were inactivated at UVC intensities of 250 µW/cm2 for 5 min or 100 µW/cm2 for 20 min. Reactivation by DNA repair was considered to be unlikely. No morphological changes were observed directly after UVC inactivation by transmission electron microscopy, but severe swelling and membrane degradation of bacteria with increasing severity occurred after 24 and 48 h. Immunization of rabbits resulted in a pronounced antibody response. UVC inactivation of C. burnetii resulted in a structural preserved, safe whole cell antigen and might be useful as antigen for diagnostic purposes or as vaccine candidate.

Vaccine development: obligate intracellular bacteria new tools, old pathogens: the current state of vaccines against obligate intracellular bacteria

Obligate intracellular bacteria have remained those for which effective vaccines are unavailable, mostly because protection does not solely rely on an antibody response. Effective antibody-based vaccines, however, have been developed against extracellular bacteria pathogens or toxins. Additionally, obligate intracellular bacteria have evolved many mechanisms to subvert the immune response, making vaccine development complex. Much of what we know about protective immunity for these pathogens has been determined using infection-resolved cases and animal models that mimic disease. These studies have laid the groundwork for antigen discovery, which, combined with recent advances in vaccinology, should allow for the development of safe and efficacious vaccines. Successful vaccines against obligate intracellular bacteria should elicit potent T cell memory responses, in addition to humoral responses. Furthermore, they ought to be designed to specifically induce strong cytotoxic CD8+ T cell responses for protective immunity. This review will describe what we know about the potentially protective immune responses to this group of bacteria. Additionally, we will argue that the novel delivery platforms used during the Sars-CoV-2 pandemic should be excellent candidates to produce protective immunity once antigens are discovered. We will then look more specifically into the vaccine development for Rickettsiaceae, Coxiella burnetti, and Anaplasmataceae from infancy until today. We have not included Chlamydia trachomatis in this review because of the many vaccine related reviews that have been written in recent years.

The lower Saint Lawrence River region of Quebec, a hot spot for sheepfold-associated Q fever in Canada: Review of 258 cases

Background

The lower Saint Lawrence river region (LSLRR), in Quebec, has a 10-fold higher incidence of Q fever compared to the provincial rate. This study aimed to review clinical cases and the Q fever risk exposure in this region.

Methods

Data were retrieved from microbiology laboratory, medical records from Rimouski Regional Hospital and Public Health reports between 1991 and 2018. They were analyzed with Epi Info 7.2.2.6. Patients with confirmed acute, probable acute, and chronic Q fever were classified using standard case definitions and mapped according to the postal code, to assess the correlation between cases and sheep distribution.

Results

Out of 295 cases, 258 were included (241 confirmed acute, seven probable acute, 10 chronic). Median age was 49 years, 76% were male. For acute cases, the prominent symptoms were fever (99%), headache (83%), chills (80%), sweating (72%), myalgia (69%), and fatigue (67%). Clinical presentation was mostly febrile syndrome with mild hepatitis (84%). A seasonal peak was observed from May to July (56% of acute cases). Most cases (56%) occurred within the two counties where sheep production was highest. Exposure to sheep was prominent 93%, including 64% direct contact (15% shepherds, 49% sheepfold visitors), 14% indirect contact, and 15% sheepfold neighbors.

Conclusions

To our knowledge, this is one of the largest retrospective studies of Q fever cases reported in Canada. Q fever in Quebec LSLRR is associated mainly with sheep exposure. Fever and hepatitis were the most common manifestations. Preventive measures should be considered in this region to protect sheepfold workers, visitors, and their neighbors.

Cytometry profiling of ex vivo recall responses to Coxiella burnetii in previously naturally exposed individuals reveals long-term changes in both adaptive and innate immune cellular compartments

Introduction

Q fever, caused by the intracellular bacterium Coxiella burnetii, is considered an occupational and biodefense hazard and can result in debilitating long-term complications. While natural infection and vaccination induce humoral and cellular immune responses, the exact nature of cellular immune responses to C. burnetii is incompletely understood. The current study seeks to investigate more deeply the nature of long-term cellular recall responses in naturally exposed individuals by both cytokine release assessment and cytometry profiling.

Methods

Individuals exposed during the 2007-2010 Dutch Q fever outbreak were grouped in 2015, based on a C. burnetii-specific IFNγ release assay (IGRA), serological status, and self-reported clinical symptoms during initial infection, into asymptomatic IGRA-negative/seronegative controls, and three IGRA-positive groups (seronegative/asymptomatic; seropositive/asymptomatic and seropositive/symptomatic). Recall responses following in vitro re-stimulation with heat-inactivated C. burnetii in whole blood, were assessed in 2016/2017 by cytokine release assays (n=55) and flow cytometry (n=36), and in blood mononuclear cells by mass cytometry (n=36).

Results

Cytokine release analysis showed significantly elevated IL-2 responses in all seropositive individuals and elevated IL-1β responses in those recovered from symptomatic infection. Comparative flow cytometry analysis revealed significantly increased IFNγ, TNFα and IL-2 recall responses by CD4 T cells and higher IL-6 production by monocytes from symptomatic, IGRA-positive/seropositive individuals compared to controls. Mass cytometry profiling and unsupervised clustering analysis confirmed recall responses in seropositive individuals by two activated CD4 T cell subsets, one characterized by a strong Th1 cytokine profile (IFNγ+IL-2+TNFα+), and identified C. burnetii-specific activation of CD8 T cells in all IGRA-positive groups. Remarkably, increased C. burnetii-specific responses in IGRA-positive individuals were also observed in three innate cell subpopulations: one characterized by an IFNγ+IL-2+TNFα+ Th1 cytokine profile and lack of canonical marker expression, and two IL-1β-, IL-6- and IL-8-producing CD14+ monocyte subsets that could be the drivers of elevated secretion of innate cytokines in pre-exposed individuals.

Discussion

These data highlight that there are long-term increased responses to C. burnetii in both adaptive and innate cellular compartments, the latter being indicative of trained immunity. These findings warrant future studies into the protective role of these innate responses and may inform future Q fever vaccine design.

Macrophage infectivity potentiator protein, a peptidyl prolyl cis-trans isomerase, essential for Coxiella burnetii growth and pathogenesis

Coxiella burnetii is a Gram-negative intracellular pathogen that causes the debilitating disease Q fever, which affects both animals and humans. The only available human vaccine, Q-Vax, is effective but has a high risk of severe adverse reactions, limiting its use as a countermeasure to contain outbreaks. Therefore, it is essential to identify new drug targets to treat this infection. Macrophage infectivity potentiator (Mip) proteins catalyse the folding of proline-containing proteins through their peptidyl prolyl cis-trans isomerase (PPIase) activity and have been shown to play an important role in the virulence of several pathogenic bacteria. To date the role of the Mip protein in C. burnetii pathogenesis has not been investigated. This study demonstrates that CbMip is likely to be an essential protein in C. burnetii. The pipecolic acid derived compounds, SF235 and AN296, which have shown utility in targeting other Mip proteins from pathogenic bacteria, demonstrate inhibitory activities against CbMip. These compounds were found to significantly inhibit intracellular replication of C. burnetii in both HeLa and THP-1 cells. Furthermore, SF235 and AN296 were also found to exhibit antibiotic properties against both the virulent (Phase I) and avirulent (Phase II) forms of C. burnetii Nine Mile Strain in axenic culture. Comparative proteomics, in the presence of AN296, revealed alterations in stress responses with H2O2 sensitivity assays validating that Mip inhibition increases the sensitivity of C. burnetii to oxidative stress. In addition, SF235 and AN296 were effective in vivo and significantly improved the survival of Galleria mellonella infected with C. burnetii. These results suggest that unlike in other bacteria, Mip in C. burnetii is required for replication and that the development of more potent inhibitors against CbMip is warranted and offer potential as novel therapeutics against this pathogen.

The Tick-Borne Pathogens: An Overview of China's Situation

BACKGROUND

Ticks are important medical arthropods that can transmit hundreds of pathogens, such as parasites, bacteria, and viruses, leading to serious public health burdens worldwide. Unexplained fever is the most common clinical manifestation of tick-borne diseases. Since the emergence of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the surge of coronavirus disease 2019 (COVID-19) cases led to the hospital overload and fewer laboratory tests for tick-borne diseases. Therefore, it is essential to review the tick-borne pathogens and further understand tick-borne diseases.

PURPOSE

The geographic distribution and population of ticks in the Northern hemisphere have expanded while emerging tick-borne pathogens have been introduced to China continuously. This paper focused on the tick-borne pathogens that are threatening public health in the world. Their medical significant tick vectors, as well as the epidemiology, clinical manifestations, diagnosis, treatment, prevention, and control measures, are emphasized in this document.

METHODS

In this study, all required data were collected from articles indexed in English databases, including Scopus, PubMed, Web of Science, Science Direct, and Google Scholar.

RESULTS

Ticks presented a great threat to the economy and public health. Although both infections by tick-borne pathogens and SARS-CoV-2 have fever symptoms, the history of tick bite and its associated symptoms such as encephalitis or eschar could be helpful for the differential diagnosis. Additionally, as a carrier of vector ticks, migratory birds may play a potential role in the geographical expansion of ticks and tick-borne pathogens during seasonal migration.

CONCLUSION

China should assess the risk score of vector ticks and clarify the potential role of migratory birds in transmitting ticks. Additionally, the individual and collective protection, vector control, comprehensive surveillance, accurate diagnosis, and symptomatic treatment should be carried out, to meet the challenge.

Factors associated with Q fever vaccination in Australian wildlife rehabilitators

Australian wildlife rehabilitators (AWR) are at risk of contracting Q fever, a serious zoonotic disease caused by Coxiella burnetii. Despite Australian government recommendations for AWR to receive Q fever vaccination (QFV), and the availability of a safe and effective vaccine in Australia, shortfalls in vaccine uptake have been observed in AWR. This study aimed to determine factors associated with QFV status and describe AWR attitudes and potential barriers towards QFV. Data were obtained from a nationwide, online, cross-sectional survey of AWR undertaken in 2018. Approximately-three quarters (200/265; 75.5 %) of those that had heard of Q fever were also aware of the Q fever vaccine, and of those, 25.5 % (51/200) were vaccinated. Barriers to QFV, among unvaccinated respondents who had also heard of Q fever and the vaccine (149/200; 74.5 %), included concerns regarding the safety, efficacy, and importance of the Q fever vaccine. Complacency toward vaccination, convenience of vaccination, and a lack of Q fever knowledge were also notable barriers. Only 27.7 % (41/148) of respondents reported having had vaccination recommended to them. Multivariable logistic regression identified that vaccinated AWR were more likely to be aged ≤ 50 years (OR 4.51, 95 % CI: 2.14-10.11), have had a university level education (OR 2.78, 95 % CI: 1.39-5.73), have resided in New South Wales/Australian Capital Territory and Queensland than in other Australian jurisdictions (OR 2.9, 95 % CI: 1.10-8.83 and OR 4.82, 95 % CI: 1.64-16.00 respectively) and have attended an animal birth (OR 2.14, 95 % CI: 1.02-4.73). Knowledge gaps regarding Q fever and QFV in AWR demonstrated the need for interventions to raise the awareness of the potential health consequences of C. burnetii exposure and Q fever prevention. Education programs to allow AWR to develop an informed perspective of Q fever and QFV, coupled with improvements in vaccine affordability and the implementation of programs to enhance accessibility, may also increase vaccine uptake.