Acute induction of cell death-related IFN stimulated genes (ISG) differentiates highly from moderately virulent CSFV strains

Classical swine fever (CSF) severity is dependent on the virulence of the CSF virus (CSFV) strain. The earliest event detected following CSFV infection is a decrease in lymphocytes number. With some CSFV strains this leads to lymphopenia, the severity varying according to strain virulence. This lymphocyte depletion is attributed to an induction of apoptosis in non-infected bystander cells. We collected peripheral blood mononuclear cells (PBMC) before and during 3 days post-infection with either a highly or moderately virulent CSFV strain and subjected them to comparative microarray analysis to decipher the transcriptomic modulations induced in these cells in relation to strain virulence. The results revealed that the main difference between strains resided in the kinetics of host response to the infection: strong and immediate with the highly virulent strain, progressive and delayed with the moderately virulent one. Also although cell death/apoptosis-related IFN stimulated genes (ISG) were strongly up-regulated by both strains, significant differences in their regulation were apparent from the observed differences in onset and extent of lymphopenia induced by the two strains. Furthermore, the death receptors apoptotic pathways (TRAIL-DR4, FASL-FAS and TNFa-TNFR1) were also differently regulated. Our results suggest that CSFV strains might exacerbate the interferon alpha response, leading to bystander killing of lymphocytes and lymphopenia, the severity of which might be due to the host’s loss of control of IFN production and downstream effectors regulation

Porcine Reproductive and Respiratory Syndrome Virus Type 1.3 Lena Triggers Conventional Dendritic Cells 1 Activation and T Helper 1 Immune Response Without Infecting Dendritic Cells

Porcine Reproductive and Respiratory Syndrome virus (PRRSV) is an arterivirus responsible for highly contagious infection and huge economic losses in pig industry. Two species, PRRSV-1 and PRRSV-2 are distinguished, PRRSV-1 being more prevalent in Europe. PRRSV-1 can further be divided in subtypes. PRRSV-1.3 such as Lena are more pathogenic than PRRSV-1.1 such as Lelystad or Flanders13. PRRSV-1.3 viruses trigger a higher Th1 response than PRRSV-1.1, although the role of the cellular immune response in PRRSV clearance remains ill defined. The pathogenicity as well as the T cell response inductions may be differentially impacted according to the capacity of the virus strain to infect and/or activate DCs. However, the interactions of PRRSV with in vivo-differentiated-DC subtypes such as conventional DC1 (cDC1), cDC2, and monocyte-derived DCs (moDC) have not been thoroughly investigated. Here, DC subpopulations from Lena in vivo infected pigs were analyzed for viral genome detection. This experiment demonstrates that cDC1, cDC2, and moDC are not infected in vivo by Lena. Analysis of DC cytokines production revealed that cDC1 are clearly activated in vivo by Lena. In vitro comparison of 3 Europeans strains revealed no infection of the cDC1 and cDC2 and no or little infection of moDC with Lena, whereas the two PRRSV-1.1 strains infect none of the 3 DC subtypes. In vitro investigation of T helper polarization and cytokines production demonstrate that Lena induces a higher Th1 polarization and IFNγ secretion than FL13 and LV. Altogether, this work suggests an activation of cDC1 by Lena associated with a Th1 immune response polarization

Macrophage-B Cell Interactions in the Inverted Porcine Lymph Node and Their Response to Porcine Reproductive and Respiratory Syndrome Virus

Swine lymph nodes (LN) present an inverted structure compared to mouse and human, with the afferent lymph diffusing from the center to the periphery. This structure, also observed in close and distant species such as dolphins, hippopotamus, rhinoceros, and elephants, is poorly described, nor are the LN macrophage populations and their relationship with B cell follicles. B cell maturation occurs mainly in LN B cell follicles with the help of LN macrophage populations endowed with different antigen delivery capacities. We identified three macrophage populations that we localized in the inverted LN spatial organization. This allowed us to ascribe porcine LN MΦ to their murine counterparts: subcapsular sinus MΦ, medullary cord MΦ and medullary sinus MΦ. We identified the different intra and extrafollicular stages of LN B cells maturation and explored the interaction of MΦ, drained antigen and follicular B cells. The porcine reproductive and respiratory syndrome virus (PRRSV) is a major porcine pathogen that infects tissue macrophages (MΦ). PRRSV is persistent in the secondary lymphoid tissues and induces a delay in neutralizing antibodies appearance. We observed PRRSV interaction with two LN MΦ populations, of which one interacts closely with centroblasts. We observed BCL6 up-regulation in centroblast upon PRRSV infection, leading to new hypothesis on PRRSV inhibition of B cell maturation. This seminal study of porcine LN will permit fruitful comparison with murine and human LN for a better understanding of normal and inverted LN development and functioning

Development of a primary cell model derived from porcine dorsal soft palate for foot-and-mouth disease virus research and diagnosis

Foot-and-mouth disease (FMD) is a highly contagious viral disease of cloven-hoofed animals that has a significant socio-economic impact. One concern associated with this disease is the ability of its etiological agent, the FMD virus (FMDV), to persist in its hosts through underlying mechanisms that remain to be elucidated. While persistence has been described in cattle and small ruminants, it is unlikely to occur in pigs. One of the factors limiting the progress in understanding FMDV persistence and, in particular, differential persistence is the lack of suitable in vitro models. A primary bovine cell model derived from the dorsal soft palate, which is the primary site of replication and persistence of FMDV in cattle, has been developed, and it seemed relevant to develop a similar porcine model. Cells from two sites of FMDV replication in pigs, namely, the dorsal soft palate and the oropharyngeal tonsils, were isolated and cultured. The epithelial character of the cells from the dorsal soft palate was then assessed by immunofluorescence. The FMDV-sensitivity of these cells was assessed after monolayer infection with FMDV O/FRA/1/2001 Clone 2.2. These cells were also grown in multilayers at the air-liquid interface to mimic a stratified epithelium susceptible to FMDV infection. Consistent with what has been shown in vivo in pigs, our study showed no evidence of persistence of FMDV in either the monolayer or multilayer model, with no infectious virus detected 28 days after infection. The development of such a model opens up new possibilities for the study and diagnosis of FMDV in porcine cells

Estimating Parameters Related to the Lifespan of Passively Transferred and Vaccine-Induced Porcine Reproductive and Respiratory Syndrome Virus Type I Antibodies by Modeling Field Data

The outputs of epidemiological models are strongly related to the structure of the model and input parameters. The latter are defined by fitting theoretical concepts to actual data derived from field or experimental studies. However, some parameters may remain difficult to estimate and are subject to uncertainty or sensitivity analyses to determine their variation range and their global impact on model outcomes. As such, the evaluation of immunity duration is often a puzzling issue requiring long-term follow-up data that are, most of time, not available. The present analysis aims at characterizing the kinetics of antibodies against Porcine Reproductive and Respiratory Syndrome virus (PRRSv) from longitudinal data sets. The first data set consisted in the serological follow-up of 22 vaccinated gilts during 21 weeks post-vaccination (PV). The second one gathered the maternally derived antibodies (MDAs) kinetics in piglets from three different farms up to 14 weeks of age. The peak of the PV serological response against PRRSv was reached 6.9 weeks PV on average with an average duration of antibodies persistence of 26.5 weeks. In the monitored cohort of piglets, the duration of passive immunity was found relatively short, with an average duration of 4.8 weeks. The level of PRRSv-MDAs was found correlated with the dams’ antibody titer at birth, and the antibody persistence was strongly related to the initial MDAs titers in piglets. These results evidenced the importance of PRRSv vaccination schedule in sows, to optimize the delivery of antibodies to suckling piglets. These estimates of the duration of active and passive immunity could be further used as input parameters of epidemiological models to analyze their impact on the persistence of PRRSv within farms

Caractérisation des mécanismes pathogéniques associés à la virulence du virus de la Peste Porcine Classique (PPC)

Le virus de la Peste Porcine Classique est responsable d'une maladie hémorragique dont les symptômes varient en fonction de la virulence des souches. L'infection provoque une diminution du nombre de lymphocytes circulants permettant de différencier les souches sur des critères d'intensité et de cinétique, dont le mode d'induction implique un processus d'apoptose. Ce phénomène étant difficile à reproduire in vitro, des porcs ont été infectés par une souche hyper ou moyennement virulente afin d'étudier les différences observées lors de la mise en place de la lymphopénie. L'analyse transcriptomique a révélé une induction plus immédiate et intense des gènes stimulés par l'interféron et associés à un processus de mort cellulaire avec la souche hyper-virulente. Pour chacune des souches, cette induction est corrélée à la présence d'interféron alpha dans le sérum ainsi qu'à l'induction de la lymphopénie. Nos résultats suggèrent que le virus exacerbe la réponse antivirale de l'hôte, conduisant à la mort des lymphocytes, et que la virulence des souches influe sur les capacités de l'hôte à maintenir un contrôle sur la régulation de cette réponse interféron.Classical Swine Fever Virus is the causal agent of an hemorrhagic disease which clinical signs depend on the strains virulence. The infection induces a blood lymphocyte depletion that however allows the strains differentiation based on intensity and kinetics measures. Its way of induction is not well described but an apoptotic process is involved. Because of the difficulty to reproduce in vitro the virus-mediated apoptosis induction in lymphocytes, we infected pigs by either a highly virulent strain, or a moderately one, in order to decipher differences when the lymphocyte depletion takes place. Microarray analysis revealed a more sudden and acute induction of cell death-related interferon stimulated genes with the highly virulent strain. For each strain, this induction is correlated to the interferon alpha presence in serum and the lymphopenia induction. Our results suggest that the virus exacerbate host's antiviral response, leading to the death of lymphocytes, and that the strains virulence affect the host's capacities to keep control on this interferon response regulation.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF

Biocatalytic composite membranes for CO2 capture

Nature has developed very active and specific catalysts that are critical for living organisms’ existence. The application of some of such biocatalysts in CO2 capture and utilization has recently attracted large interest from the research community and the industry [1,2]. For example, they have been applied to CO2 absorption aiming to reduce the liquid side mass transfer resistance. This resistance is dominating the overall mass transfer and it can be reduced by catalyzing the slow CO2 hydration reaction. Besides, they have also been incorporated in selective membranes. These membranes usually displayed improved permeability and selectivity due to the facilitated transport mechanism [2]. In addition, these biocatalysts are usually immobilized in/on a carrier to protect them from the harsh conditions in CO2 capture and ensure long-term stability. Depending on the immobilization method, the immobilization results in different degrees of stabilization and activity loss. We report here the fabrication and characterization of novel composite membranes with immobilized biocatalyst for CO2 bioconversion. These membranes were prepared by a novel method that ensured a good and straightforward biocatalyst immobilization. The membranes were structurally characterized by SEM while their activity in different conditions was evaluated using p-NPA hydrolysis. In addition, to demonstrate their applicability, the biocatalytic composite membranes were tested in a gas absorption set-up showing an increase in the overall mass transfer coefficient with respect to the pristine support. These membranes could also be interesting for other applications as the combination of a selective barrier and the biocatalyst leads to process intensification (reaction + separation in the same device). [1] P. Luis, V. Sang Sefidi, M. Sparenberg, M. Garcia Alvarez. (2021), continuous process and system for the production of sodium bicarbonate crystals, 20211693.5-1108, universite catholique de louvain. (Patent) [2] Molina-Fernández, C., & Luis, P. (2021). Immobilization of carbonic anhydrase for CO2 capture and its industrial implementation: A review. Journal of CO2 Utilization, 47, 101475