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•We evaluated swine influenza A transmission virus in piglets with different MDA statuses after a single-dose vaccination.•The transmission rate of the challenge strain was found 3.6 time greater in MDA-positive than in MDA-negative pigs.•Estimated parameters were unsed to feed a mechanistic model of SwIAV transmission in a farrow-to-finish pig farm.•An extended SwIAV within-farm persistence was observed when both sows and piglets were batch-to-batch vaccinated.•Alternative vaccination schemes need to be tested, accounting for population dynamics and hosts’ immune statuses. Swine influenza A virus (swIAV) is a major pathogen affecting pigs with a huge economic impact and potentially zoonotic. Epidemiological studies in endemically infected farms permitted to identify critical factors favoring on-farm persistence, among which maternally-derived antibodies (MDAs). Vaccination is commonly practiced in breeding herds and might be used for immunization of growing pigs at weaning. Althoughinterference between MDAs and vaccination was reported in young piglets, its impact on swIAV transmission was not yet quantified. To this aim, this study reports on a transmission experiment in piglets with or without MDAs, vaccinated with a single dose injection at four weeks of age, and challenged 17 days post-vaccination. To transpose small-scale experiments to real-life situation, estimated parameters were used in a simulation tool to assess their influence at the herd level. Based on a thorough follow-up of the infection chain during the experiment, the transmission of the swIAV challenge strain was highly dependent on the MDA status of the pigs when vaccinated. MDA-positive vaccinated animals showed a direct transmission rate 3.6-fold higher than the one obtained in vaccinated animals without MDAs, estimated to 1.2. Vaccination nevertheless reduced significantly the contribution of airborne transmission when compared with previous estimates obtained in unvaccinated animals. The integration of parameter estimates in a large-scale simulation model, representing a typical farrow-to-finish pig herd, evidenced an extended persistence of viral spread when vaccination of sows and single dose vaccination of piglets was hypothesized. When extinction was quasi-systematic at year 5 post-introduction in the absence of sow vaccination but with single dose early vaccination of piglets, the extinction probability fell down to 33% when batch-to-batch vaccination was implemented both in breeding herd and weaned piglets. These results shed light on a potential adverse effect of single dose vaccination in MDA-positive piglets, which might lead to longer persistence of the SwIAV at the herd level.

Mathematical modelling is nowadays a pivotal tool for infectious diseases studies, completing regular biological investigations. The rapid growth of computer technology allowed for development of computational tools to address biological issues that could not be unravelled in the past. The global understanding of viral disease dynamics requires to account for all interactions at all levels, from within-host to between-herd, to have all the keys for development of control measures. A literature review was performed to disentangle modelling frameworks according to their major objectives and methodologies. One hundred and seventeen articles published between 1994 and 2020 were found to meet our inclusion criteria, which were defined to target papers representative of studies dealing with models of viral infection dynamics in pigs. A first descriptive analysis, using bibliometric indexes, permitted to identify keywords strongly related to the study scopes. Modelling studies were focused on particular infectious agents, with a shared objective: to better understand the viral dynamics for appropriate control measure adaptation. In a second step, selected papers were analysed to disentangle the modelling structures according to the objectives of the studies. The system representation was highly dependent on the nature of the pathogens. Enzootic viruses, such as swine influenza or porcine reproductive and respiratory syndrome, were generally investigated at the herd scale to analyse the impact of husbandry practices and prophylactic measures on infection dynamics. Epizootic agents (classical swine fever, foot-and-mouth disease or African swine fever viruses) were mostly studied using spatio-temporal simulation tools, to investigate the efficiency of surveillance and control protocols, which are predetermined for regulated diseases. A huge effort was made on model parameterization through the development of specific studies and methodologies insuring the robustness of parameter values to feed simulation tools. Integrative modelling frameworks, from within-host to spatio-temporal models, is clearly on the way. This would allow to capture the complexity of individual biological variabilities and to assess their consequences on the whole system at the population level. This would offer the opportunity to test and evaluate in silico the efficiency of possible control measures targeting specific epidemiological units, from hosts to herds, either individually or through their contact networks. Such decision support tools represent a strength for stakeholders to help mitigating infectious diseases dynamics and limiting economic consequences.

Transmission characteristics of PCV2 have been compared between vaccinated and non-vaccinated pigs in experimental conditions. Twenty-four Specific Pathogen Free (SPF) piglets, vaccinated against PCV2 at 3weeks of age (PCV2a recombinant CAP protein-based vaccine), were inoculated at 15days post-vaccination with a PCV2b inoculum (6⋅105 TCID50), and put in contact with 24 vaccinated SPF piglets during 42days post-inoculation. Those piglets were shared in six replicates of a contact trial involving 4 inoculated piglets mingled with 4 susceptible SPF piglets. Two replicates of a similar contact trial were made with non-vaccinated pigs. Non vaccinated animals received a placebo at vaccination time and were inoculated the same way and at the same time as the vaccinated group. All the animals were monitored twice weekly using quantitative real-time PCR and ELISA for serology until 42days post-inoculation. The frequency of infection and the PCV2 genome load in sera of the vaccinated pigs were significantly reduced compared to the non-vaccinated animals. The duration of infectiousness was significantly different between vaccinated and non-vaccinated groups (16.6days [14.7;18.4] and 26.6days [22.9;30.4] respectively). The transmission rate was also considerably decreased in vaccinated pigs (β=0.09 [0.05–0.14] compared to β=0.19 [0.11–0.32] in non-vaccinated pigs). This led to an estimated reproduction ratio of 1.5 [95% CI 0.8 – 2.2] in vaccinated animals versus 5.1 [95% CI 2.5 – 8.2] in non-vaccinated pigs when merging data of this experiment with previous trials carried out in same conditions.

Some vaccination strategies have shown good results in reducing the clinical outcomes of PRRS. Nevertheless the effect of vaccines on viral transmission is poorly described, so we aimed to fill this gap with the present study. Twelve Specific Pathogen Free (SPF) piglets, vaccinated against PRRSv at 3 weeks of age (Porcilis PRRS ID®, MSD), were inoculated at 31 days post-vaccination with a heterologous genogroup 1.1 strain, and put in contact with 12 vaccinated piglets during 49 days. The same protocol was carried out simultaneously with SPF non-vaccinated piglets. Piglets were monitored individually for clinical symptoms on a daily basis and individual blood samples were taken twice a week. In inoculated piglets, the genome viral load specific to the inoculated strain was reduced and viraemia shortened in vaccinated piglets (28 days versus 38 days in non vaccinated piglets). In contact pigs, the challenge strain was detected in the serum of only one vaccinated piglet whereas it was detected in all contact non-vaccinated piglets. Transmission parameters were estimated by a Bayesian analysis of transmission data in the two groups. The estimated transmission rate was 10-times lower in vaccinated than in non-vaccinated piglets and the duration of infectiousness was reduced, leading to a reproduction ratio R significantly lower (0.30 [0.05–0.96] versus 5.42 [2.94–9.04] in non vaccinated piglets). Hence, in our experimental conditions, vaccination was able to decrease considerably PRRSv spread. A complementary evaluation in field conditions would be required to identify circumstances associated with infection control failures that can be observed in pig farms.

Wild boar density has been suggested to play a role in shaping African swine fever (ASF) transmission patterns. To provide quantitative estimates of the influence of wild boar density on ASF spread, a spatially‐explicit detection‐delay SIR mechanistic model of ASF transmission among density‐explicit wild boar habitat was developed and parameterised to observed epidemic data in northern Italy from January 2022 through September 2023. Wild boar density estimates were generated by the ENETWILD consortium. Infectious periods, local prevalence at time of first detection, detection rates, and seasonal recovery rates were estimated directly from surveillance data. Eight models were constructed utilizing static and seasonal transmission rates along with linear relationships between habitat susceptibility/infectivity and wild boar density. Transmission rate, relative susceptibility, and relative infectivity were estimated by fitting each model to the observed epidemic using sequential Monte Carlo approximate Bayesian computation. The model that most closely fit the full data used a seasonal transmission rate but did not support a wild boar density effect on ASF spread across the entire study period. However, further analyses of the model outputs suggest that wild boar density likely played a role in shaping ASF transmission patterns during the second wave only (October 2022 – September 2023). This observation could be due to a lack of power in the first wave, lower surveillance rates in that period, or be from density estimates no longer reflecting the true wild boar density distributions upon the start of the second wave. These results demonstrate that wild boar density impacted ASF propagation in northern Italy. Further investigation by estimating parameters for individual epidemic waves could be beneficial to better characterise the wave‐specific impact of wild boar density. The model developed here could be used in other contexts to evaluate if the influence of wild boar density is present across epidemic scenarios.

The aim of this study was to investigate the fitness of macrolide resistant Campylobacter coli and Campylobacter jejuni . The in vitro growth, the survival on food matrix, and the in vivo colonization of C. jejuni and C. coli susceptible isolates and their isogenic resistant mutants were studied. In vitro experiments demonstrated that macrolide resistance imposed a fitness cost when the susceptible strains and their isogenic resistant mutants were cultured in competition. When inoculated in food matrix, the resistant C. jejuni mutant was no longer detectable after 3 to 5 days but the susceptible strain remained detectable for over 18 days. No difference in survival in food matrix was observed between susceptible and resistant C. coli . When inoculated in vivo in chickens, the macrolide susceptible and resistant C. coli displayed similar levels of colonization, both in separated inoculations and during competitive assays. Strikingly, when mono-inoculated or co-inoculated into chickens, macrolide susceptible C. jejuni outcompeted the macrolide resistant population. However, a spontaneous mutant that evolved in vivo showed a colonization capacity similar to the susceptible strain. Our findings demonstrate the effect of macrolide resistance on the fitness of Campylobacter but suggest that evolved mutants may be as fit as susceptible strains.

Hybrid organic–inorganic materials exhibit so versatile properties that they can be considered one of the most interesting classes of materials for photonic applications, for the development of both passive and active devices. A synthetic route used for the preparation of nanostructured organic/inorganic (O/I) materials is the assembling of nano-building blocks (NBBs). This approach allows controlling the extent of phase interaction, which in its turn governs the structure-properties relationships. The non-hydrolytic sol–gel process is recognized as a useful route for the preparation of nanostructured molecular units. The condensation reaction of methacryloxypropyl trimethoxysilane and diphenylsilanediol in a non-hydrolytic sol–gel process has been exploited in order to synthesize nanostructured molecular units for the preparation of hybrid organic/inorganic coatings. The non-hydrolytic condensation reactions were run adding different compounds such as triethylamine, titanium isopropoxide, titanium chloride, and dibutyldilauryltin as condensation promoters. The NBB synthesis was also run under controlled hydrolitic conditions, by exploiting the in situ water production using an ethanol/acetic acid mixture. These reactions have been compared in terms of the influence of the employed reagents on the condensation degree and the product structure. Multinuclear NMR, ATR-FTIR and FT-Raman techniques have been used to study the reaction steps and characterize the final condensation products. Hybrid O/I materials have been prepared by assembling methacrylate-based NBBs in the presence of suitable thermal and photo-initiators. The study on the progress of the thermal polymerization process using differential scanning calorimetry (DSC) will be presented, as well as the preliminary results on the two photon polymerization (TPP) process for the preparation of patternable films.

A convenient strategy for synthesis of a pentaerythritol derivative diacetal containing azo functions is presented; NMR data are discussed and are in good agreement with the molecular structure.

ABSTRACT IN FRENCH: Essentiel à toute recherche, le choix d'un protocole méthodologique se doit d'être pertinent. Pertinent par rapport à la discipline, par rapport au sujet, par rapport aux objectifs de l'étude. Dans cette perspective, cet essai de réflexion se veut être une présentation, étape par étape, d'une démarche méthodologique, depuis les prémices de la recherche jusqu'au dépouillement et l'analyse critique des matériaux et des sources. Afin de répondre à cette ambition, l'article présente une méthodologie spécifique: la prosopographie. En effet, l'objectif n'est pas, ici, de faire état de la multiplicité des méthodes d'analyses en sciences humaines mais de présenter toute la rigueur d'un protocole et d'un processus de réflexion en prenant appui sur le cas précis d'un sujet de recherche. // ABSTRACT IN SPANISH: Esencial a toda investigación, la elección de un protocolo metodológico debe ser pertinente con respecto a la disciplina, al tema y a los objetivos del estudio. Dentro de esa perspectiva, este intento de reflexión pretende ser une presentación, etapa por etapa, de un procedimiento metodológico, desde las premisas de la investigación hasta el examen y el análisis crítico de materiales y fuentes. Con el propósito de responder a esta ambición, el artículo presenta una metodología específica: la prosopografía. En efecto, el objectivo no es hacer aquí un estado de la multiplicidad de los métodos de análisis en ciencias humanas sino presentar todo el rigor de un protocolo y de un proceso de reflexión tomando apoyo en el caso preciso de un tema de investigación. // ABSTRACT IN ENGLISH: Essential to all types of research, the choice of a methodological procedure must be relevant to the discipline, the theme and the aims of the study. Within this perspective, this attempt to elaborate a thought pretends to be a presentation, step by step, of a methodological procedure, from the beginnings of the research till the examination and critical analysis of materials and sources. Trying to respond to such ambition, this article presents a specific method: prosography. Indeed, the object here is not to display a survey of the multiple methods of analysis in human sciences, but to present the complete precision of a procedure and of a stream of thought by basing the arguments upon the case of a precise research subject. Reprinted by permission of Presses Universitaires du Mirail