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Since the reintroduction of African swine fever virus (ASFV) in Europe in 2007 and its subsequent spread to Asia, wild boar has played a crucial role in maintaining and disseminating the virus. There are significant gaps in the knowledge regarding infection dynamics and disease pathogenesis in domestic pigs and wild boar, particularly at the early infection stage. We aimed to compare domestic pigs and wild boar infected intranasally to mimic natural infection with one of the original highly virulent genotype II ASFV isolates (Armenia 2007). The study involved euthanising three domestic pigs and three wild boar on days 1, 2, 3, and 5 post-infection, while four domestic pigs and four wild boar were monitored until they reached a humane endpoint. The parameters assessed included clinical signs, macroscopic lesions, viremia levels, tissue viral load, and virus shedding in nasal and rectal swabs from day 1 post-infection. Compared with domestic pigs, wild boar were more susceptible to ASFV, with a shorter incubation period and earlier onset of clinical signs. While wild boar reached a humane endpoint earlier than domestic pigs did, the macroscopic lesions were comparatively less severe. In addition, wild boar had earlier viremia, and the virus was also detected earlier in tissues. The medial retropharyngeal lymph nodes were identified as key portals for ASFV infection in both subspecies. No viral genome was detected in nasal or rectal swabs until shortly before reaching the humane endpoint in both domestic pigs and wild boar, suggesting limited virus shedding in acute infections. [ABSTRACT FROM AUTHOR]

African swine fever (ASF) is a contagious viral disease of suids that induces high mortality in domestic pigs and wild boars. Given the current spread of ASF, the development of a vaccine is a priority. During an attempt to inactivate the Georgia 2007/1 strain via heat treatment, we fortuitously generated an attenuated strain called ASFV-989. Compared to Georgia, the ASFV-989 strain genome has a deletion of 7458 nucleotides located in the 5′-end encoding region of MGF 505/360, which allowed for developing a DIVA PCR system. In vitro, in porcine alveolar macrophages, the replication kinetics of the ASFV-989 and Georgia strains were identical. In vivo, specific-pathogen-free (SPF) pigs inoculated with the ASFV-989 strain, either intramuscularly or oronasally, exhibited transient hyperthermia and slightly decreased growth performance. Animals immunized with the ASFV-989 strain showed viremia 100 to 1000 times lower than those inoculated with the Georgia strain and developed a rapid antibody and cell-mediated response. In ASFV-989-immunized pigs challenged 2 or 4 weeks later with the Georgia strain, no symptoms were recorded and no viremia for the challenge strain was detected. These results show that the ASFV-989 strain is a promising non-GMO vaccine candidate that is usable either intramuscularly or oronasally. [ABSTRACT FROM AUTHOR]

Aujeszky's disease virus (ADV), also known as pseudorabies virus, causes an important neurological infection with a major economic and health impact on animal husbandry. Here, we serologically screened muscle fluid from wild boar (Sus scrofa) for the presence of anti-ADV antibodies. Animals were caught during two hunting seasons (2019–2020 and 2021–2022) from three areas in southeastern France known to be endemic with wild boar populations. A total of 30.33% of the 399 tested animals scored positive for anti-glycoprotein B antibodies directed against ADV using a commercial competitive ELISA test. A significant effect (p-value < 0.0001) of the geographical location and animal age on ADV seroprevalence was observed. The results of this study confirmed the importance of wild boar in the epidemiology of ADV in southeastern France. [ABSTRACT FROM AUTHOR]

Résumé: La peste porcine africaine (PPA) est une maladie hautement pathogène causant une fièvre hémorragique chez les suidés domestiques et sauvages. Elle est responsable de nombreuses épizooties notamment en Europe et en Asie, causant de grandes pertes économiques pour la filière porcine. Le virus de la peste porcine africaine (ASFV) est l'agent étiologique responsable de cette maladie. C'est un virus avec un génome à ADN double brin de grande taille, codant pour plus de 150 protéines. Différents travaux ont montré qu'il existe une étroite relation entre la capacité de certaines protéines virales à inhiber la réponse interféron de type I (IFN-I) et les processus d'atténuation et de virulence pour l'ASFV. Cette revue décrit les mécanismes d'inhibition de la réponse IFN-I par les protéines d'ASFV permettant d'expliquer sur le plan moléculaire l'échappement à la réponse immunitaire innée. African swine fever (ASF) is a highly pathogenic disease causing haemorrhagic fever in domestic and wild swine. It is responsible for numerous epizootics, particularly in Europe and Asia, causing major economic losses for the pig industry. African Swine Fever virus (ASFV) is the etiological agent responsible for this disease. It is a very large double-stranded DNA virus, encoding for over 150 proteins. Various studies have shown that there is a close relationship between the ability of some viral proteins to inhibit the type I interferon (IFNI) response and the attenuation and virulence processes of ASFV. This review describes the mechanisms of inhibition of the IFN-I response by ASFV proteins, which provide a molecular explanation of how ASFV escapes the innate immune response. [ABSTRACT FROM AUTHOR]

Résumé: La peste porcine classique (PPC) est une maladie très contagieuse, spécifique des suidés, qui continue à constituer une menace pour la production porcine malgré un statut indemne de la plupart des pays de l'Union européenne. La PPC est causée par un virus de la famille des Flaviviridae appartenant au genre Pestivirus , en extension depuis les cinq dernières années avec la découverte de nouvelles espèces, notamment chez le porc ou autres animaux de rente dont la proximité génétique avec le virus de la PPC pourrait davantage compliquer le diagnostic de laboratoire. La diversité des formes de la maladie, et notamment la fréquence accrue des formes atténuées et inapparentes liée à une évolution des souches du virus de la PPC vers une réduction de leur virulence, retarde le diagnostic clinique. Ainsi, une longue période peut s'écouler avant la détection d'un foyer, permettant au virus de la PPC de circuler plus longuement, avec le risque de diffuser vers des zones géographiques éloignées des premiers cas d'infection. Les efforts doivent être maintenus en termes de surveillance et de développement d'outils de diagnostic afin de détecter précocement une infection par le virus de la PPC et ainsi limiter la propagation de la maladie et faciliter les mesures de contrôle. Classical swine fever (CSF) is a highly contagious swine-specific disease which may have a huge economic impact for porcine production. CSF is caused by a virus belonging to the Pestivirus genus, which has expanded for the past 5 years with the discovery of new species whose genetic proximity to the CSF virus could further complicate laboratory diagnosis. The various forms of the disease, and in particular the increased frequency of attenuated forms, linked to an evolution of CSF virus strains towards a reduction in their virulence, delay clinical diagnosis. Thus, a long period may elapse before an outbreak is detected, allowing the virus to circulate longer, with the risk of spreading to distant geographical areas. Efforts must be maintained in terms of surveillance and diagnostic tools development in order to detect CSF virus infection early and thus limit the spread of the disease and facilitate control measures. [ABSTRACT FROM AUTHOR]

African swine fever (ASF) represents a global threat with huge economic consequences for the swine industry. Even though direct contact is likely to be the main transmission route from infected to susceptible hosts, recent epidemiological investigations have raised questions regarding the role of haematophagous arthropods, in particular the stable fly (Stomoxys calcitrans). In this study, we developed a mechanistic vector‐borne transmission model for ASF virus (ASFV) within an outdoor domestic pig farm in order to assess the relative contribution of stable flies to the spread of the virus. The model was fitted to the ecology of the vector, its blood‐feeding behaviour and pig‐to‐pig transmission dynamic. Model outputs suggested that in a context of low abundance (<5 flies per pig), stable flies would play a minor role in the spread of ASFV, as they are expected to be responsible for around 10% of transmission events. However, with abundances of 20 and 50 stable flies per pig, the vector‐borne transmission would likely be responsible for almost 30% and 50% of transmission events, respectively. In these situations, time to reach a pig mortality of 10% would be reduced by around 26% and 40%, respectively. The sensitivity analysis emphasized that the expected relative contribution of stable flies was strongly dependent on the volume of blood they regurgitated and the infectious dose for pigs. This study identified crucial knowledge gaps that need to be filled in order to assess more precisely the potential contribution of stable flies to the spread of ASFV, including a quantitative description of the populations of haematophagous arthropods that could be found in pig farms, a better understanding of blood‐feeding behaviours of stable flies and the quantification of the probability that stable flies partially fed with infectious blood transmit the virus to a susceptible pig during a subsequent blood‐feeding attempt. [ABSTRACT FROM AUTHOR]

To deal with the limited literature data on the vectorial capacity of blood‐feeding arthropods (BFAs) and their role in the transmission of African swine fever virus (ASFV) in Metropolitan France, a dedicated working group of the French Agency for Food, Environmental and Occupational Health & Safety performed an expert knowledge elicitation. In total, 15 different BFAs were selected as potential vectors by the ad hoc working group involved. Ten criteria were considered to define the vectorial capacity: vectorial competence, current abundance, expected temporal abundance, spatial distribution, longevity, biting rate, active dispersal capacity, trophic preferences for Suidae, probability of contact with domestic pigs and probability of contact with wild boar. Fourteen experts participated to the elicitation. For each BFA, experts proposed a score (between 0 and 3) for each of the above criteria with an index of uncertainty (between 1 and 4). Overall, all experts gave a weight for all criteria (by distributing 100 marbles). A global weighted sum of score per BFA was calculated permitting to rank the different BFAs in decreasing order. Finally, a regression tree analysis was used to group those BFAs with comparable likelihood to play a role in ASF transmission. Out of the ten considered criteria, the experts indicated vectorial competence, abundance and biting rate as the most important criteria. In the context of Metropolitan France, the stable fly (Stomoxys calcitrans) was ranked as the most probable BFA to be a vector of ASFV, followed by lice (Haematopinus suis), mosquitoes (Aedes, Culex and Anopheles), Culicoides and Tabanidea. Since scientific knowledge on their vectorial competence for ASF is scarce and associated uncertainty on expert elicitation moderate to high, more studies are however requested to investigate the potential vector role of these BFAs could have in ASFV spread, starting with Stomoxys calcitrans. [ABSTRACT FROM AUTHOR]

Background: Several species of soft ticks in genus Ornithodoros are known vectors and reservoirs of African swine fever virus (ASFV). However, the underlying mechanisms of vector competence for ASFV across Ornithodoros species remain to be fully understood. To that end, this study compared ASFV replication and dissemination as well as virus vertical transmission to descendants between Ornithodorosmoubata, O. erraticus, and O. verrucosus in relation to what is known about the ability of these soft tick species to transmit ASFV to pigs. To mimic the natural situation, a more realistic model was used where soft ticks were exposed to ASFV by allowing them to engorge on viremic pigs. Methods: Ornithodoros moubata ticks were infected with the ASFV strains Liv13/33 (genotype I) or Georgia2007/1 (genotype II), O. erraticus with OurT88/1 (genotype I) or Georgia2007/1 (genotype II), and O. verrucosus with Ukr12/Zapo (genotype II), resulting in five different tick–virus pairs. Quantitative PCR (qPCR) assays targeting the VP72 ASFV gene was carried out over several months on crushed ticks to study viral replication kinetics. Viral titration assays were also carried out on crushed ticks 2 months post infection to confirm virus survival in soft ticks. Ticks were dissected. and DNA was individually extracted from the following organs to study ASFV dissemination: intestine, salivary glands, and reproductive organs. DNA extracts from each organ were tested by qPCR. Lastly, larval or first nymph-stage progeny emerging from hatching eggs were tested by qPCR to assess ASFV vertical transmission. Results: Comparative analyses revealed higher rates of ASFV replication and dissemination in O. moubata infected with Liv13/33, while the opposite was observed for O. erraticus infected with Georgia2007/1 and for O. verrucosus with Ukr12/Zapo. Intermediate profiles were found for O. moubata infected with Georgia2007/1 and for O. erraticus with OurT88/1. Vertical transmission occurred efficiently in O. moubata infected with Liv13/33, and at very low rates in O. erraticus infected with OurT88/1. Conclusions: This study provides molecular data indicating that viral replication and dissemination in Ornithodoros ticks are major mechanisms underlying ASFV horizontal and vertical transmission. However, our results indicate that other determinants beyond viral replication also influence ASFV vector competence. Further research is required to fully understand this process in soft ticks. [ABSTRACT FROM AUTHOR]

In Europe, African swine fever virus (ASFV) is one of the most threatening infectious transboundary diseases of domestic pigs and wild boar. In September 2018, ASF was detected in wild boar in the South of Belgium. France, as a bordering country, is extremely concerned about the ASF situation in Belgium, and an active preparedness is ongoing in the country. One of the questions raised by this situation relates to disturbing activities that may affect wild boar movements and their possible impact on the spread of ASFV. Despite evidence of disturbance related to hunting practices, there is a paucity of information on the impact of forestry and human leisure activities. To assess this impact on wild boar movements, a systematic review was first conducted but very few useful data were obtained. For this reason, an expert elicitation was carried out by the French Agency for Food, Environmental and Occupational Health & Safety in order to deal with this knowledge gap. A total of 30 experts originating from France and adjacent neighbouring countries (Spain, Belgium and Switzerland) were elicited about the relative importance of six factors of spatial disturbance of wild boar (noise, smell, invasion of space, modification of the environment, duration and frequency of the activity). Then, for each factor of disturbance, they were asked about the impact of 16 different commercial forestry and human leisure activities. A global weighted score was estimated in order to capture the variability of a wide range of territorial conditions and the uncertainty of expert elicitation. This estimate permitted ranking all 16 activities and aggregating them in three groups according to their potential for disturbance of wild boar, using a regression tree analysis. The results of this expert elicitation provide a methodological approach that may be useful for French and other European decision makers and stakeholders involved in the crisis management of ASF. [ABSTRACT FROM AUTHOR]

African swine fever (ASF) is a lethal hemorrhagic disease in domestic pigs and wild suids caused by African swine fever virus (ASFV), which threatens the swine industry globally. In its native African enzootic foci, ASFV is naturally circulating between soft ticks of the genus Ornithodoros, especially in the O. moubata group, and wild reservoir suids, such as warthogs (Phacochoerus spp.) that are bitten by infected soft ticks inhabiting their burrows. While the ability of some Afrotropical soft ticks to transmit and maintain ASFV is well established, the vector status of Palearctic soft tick species for ASFV strains currently circulating in Eurasia remains largely unknown. For example, the Iberian soft tick O. erraticus is a known vector and reservoir of ASFV, but its ability to transmit different ASFV strains has not been assessed since ASF re-emerged in Europe in 2007. Little is known about vector competence for ASFV in other species, such as O. verrucosus, which occurs in southern parts of Eastern Europe, including Ukraine and parts of Russia, and in the Caucasus. Therefore, we conducted transmission trials with two Palearctic soft tick species, O. erraticus and O. verrucosus, and the Afrotropical species O. moubata. We tested the ability of ticks to transmit virulent ASFV strains, including one of direct African origin (Liv13/33), and three from Eurasia that had been involved in previous (OurT88/1), and the current epizooties (Georgia2007/1 and Ukr12/Zapo). Our experimental results showed that O. moubata was able to transmit the African and Eurasian ASFV strains, whereas O. erraticus and O. verrucosus failed to transmit the Eurasian ASFV strains. However, naïve pigs showed clinical signs of ASF when inoculated with homogenates of crushed O. erraticus and O. verrucosus ticks that fed on viraemic pigs, which proved the infectiousness of ASFV contained in the ticks. These results documented that O. erraticus and O. verrucosus are unlikely to be capable vectors of ASFV strains currently circulating in Eurasia. Additionally, the persistence of infection in soft ticks for several months reaffirms that the infectious status of a given tick species is only part of the data required to assess its vector competence for ASFV. [ABSTRACT FROM AUTHOR]

Porcine reproductive and respiratory syndrome virus (PRRSV) replicates primarily in pulmonary alveolar macrophages (PAMs) and the resulting lung damage is influenced by strain virulence. To better understand the pathogenesis of PRRSV infection, we performed a longitudinal study of the PAM population and lung cytokines in specific pathogen-free pigs infected either with the highly pathogenic Lena strain or with the low pathogenic Finistere strain in comparison to uninfected pigs. Bronchoalveolar lavage fluid (BALF) and blood were collected to follow viral, cellular and cytokine changes in lung with respect to clinical signs and systemic events. Compared to Finistere-infected pigs, Lena-infected pigs exhibited more severe clinical signs and 10- to 100-fold higher viral loads in BALF and blood. Similarly, they showed an earlier drop in BALF cell viability and phagocytic activity along with a decrease in the macrophage count. From 8 to 15 days post-infection (dpi), monocytes increased both in BALF and blood from Lena-infected pigs. BALF and blood showed contrasting cytokine patterns, with low increase of IFN-α and TNF-α levels and high increase for IL-1α and IL-8 in BALF after Lena-infection. In contrast, in the blood, the increase was marked for IFN-α and TNF-α but limited for IL-1β and IL-8. Down-regulation of PAM functions combined with inflammatory cytokine and monocyte recruitment may promote lung pathogenesis and virus replication in PRRSV infections with the highly pathogenic Lena strain. In contrast, the low pathogenic Finistere strain showed prolonged viral replication in lung, possibly related to the weak IFN-γ response. [ABSTRACT FROM AUTHOR]

African swine fever is a haemorrhagic disease in pig production that can have disastrous financial consequences for farming. No vaccines are currently available and animal slaughtering or area zoning to restrict risk-related movements are the only effective measures to prevent the spread of the disease. Ornithodoros soft ticks are known to transmit the African swine fever virus (ASFV) to pigs in farms, following the natural epidemiologic cycle of the virus. Tick saliva has been shown to modulate the host physiological and immunological responses during feeding on skin, thus affecting viral infection. To better understand the interaction between soft tick, ASFV and pig at the bite location and the possible influence of tick saliva on pig infection by ASFV, salivary gland extract (SGE) of Ornithodoros porcinus, co-inoculated or not with ASFV, was used for intradermal auricular inoculation. Our results showed that, after the virus triggered the disease, pigs inoculated with virus and SGE presented greater hyperthermia than pigs inoculated with virus alone. The density of Langerhans cells was modulated at the tick bite or inoculation site, either through recruitment by ASFV or inhibition by SGE. Additionally, SGE and virus induced macrophage recruitment each. This effect was enhanced when they were co-inoculated. Finally, the co-inoculation of SGE and virus delayed the early local spread of virus to the first lymph node on the inoculation side. This study has shown that the effect of SGE was powerful enough to be quantified in pig both on the systemic and local immune response. We believe this model should be developed with infected tick and could improve knowledge of both tick vector competence and tick saliva immunomodulation. [ABSTRACT FROM AUTHOR]

Oral mass vaccination (OMV) is considered as an efficient strategy for controlling classical swine fever (CSF) in wild boar. After the completion of vaccination, the presence of antibodies in 6-12 month-old hunted wild boars was expected to reflect a recent CSF circulation. Nevertheless, antibodies could also correspond to the long-lasting of maternal antibodies. This paper relates an experience of surveillance which lasted 4 years after the completion of OMV in a formerly vaccinated area, in north-eastern France (2010-2014). First, we conducted a retrospective analysis of the serological data collected in 6-12 month-old hunted wild boars from 2010 up to 2013, using a spatial Bayesian model accounting for hunting data autocorrelation and heterogeneity. At the level of the whole area, seroprevalence in juvenile boars decreased from 28% in 2010-2011 down to 1% in 2012-2013, but remained locally high (above 5%). The model revealed the existence of one particular seroprevalence hot-spot where a longitudinal survey of marked animals was conducted in 2013-2014, for deciphering the origin of antibodies. Eleven out of 107 captured piglets were seropositive when 3-4 months-old, but their antibody titres progressively decreased until 6-7 months of age. These results suggest piglets were carrying maternal antibodies, few of them carrying maternal antibodies lasting until the hunting season. Our study shows that OMV may generate confusion in the CSF surveillance several years after the completion of vaccination. We recommend using quantitative serological tools, hunting data modelling and capture approaches for better interpreting serological results after vaccination completion. Surveillance perspectives are further discussed. [ABSTRACT FROM AUTHOR]

Classical swine fever (CSF) is among the most detrimental diseases for the swine industry worldwide. Infected wild boar populations can play a crucial role in CSF epidemiology and controlling wild reservoirs is of utmost importance for preventing domestic outbreaks. Oral mass vaccination (OMV) has been implemented to control CSF in wild boars and limit the spill over to domestic pigs. This retrospective overview of vaccination experiences illustrates the potential for that option. The C-strain live vaccine was confirmed to be highly efficacious and palatable baits were developed for oral delivery in free ranging wild boars. The first field trials were performed in Germany in the 1990's and allowed deploying oral baits at a large scale. The delivery process was further improved during the 2000's among different European countries. Optimal deployment has to be early regarding disease emergence and correctly designed regarding the landscape structure and the natural food sources that can compete with oral baits. OMV deployment is also highly dependent on a local veterinary support working closely with hunters, wildlife and forestry agencies. Vaccination has been the most efficient strategy for CSF control in free ranging wild boar when vaccination is wide spread and lasting for a sufficient period of time. Alternative disease control strategies such as intensified hunting or creating physical boundaries such as fences have been, in contrast, seldom satisfactory and reliable. However, monitoring outbreaks has been challenging during and after vaccination deployment since OMV results in a low probability to detect virus-positive animals and the live-vaccine currently available does not allow serological differentiation of infected from vaccinated animals. The development of a new marker vaccine and companion test is thus a promising option for better monitoring outbreaks during OMV deployment as well as help to better determine when to stop vaccination efforts. After rabies in red fox, the use of OMV against CSF in European wild boar can be considered as a second example of successful disease control in wildlife. The 30 years of disease control experience included in this review may provide options for improving future disease management within wild populations. [ABSTRACT FROM AUTHOR]

Constitutive humoral immunity (CHI) is thought to be a first-line of protection against pathogens invading vertebrate hosts. However, clear evidence that CHI correlates with host fitness in natural conditions is still lacking. This study explores the relationship between CHI, measured using a haemagglutination-haemolysis assay (HAHL), and resistance to classical swine fever virus (CSFV) among wild boar piglets. The individual dynamics of HAHL during piglet growth was analysed, using 423 serum samples from 92 piglets repeatedly captured in the absence of CSFV (in 2006) within two areas showing contrasting food availability. Natural antibody levels increased with age, but, in the youngest piglets antibody levels were higher in individuals from areas with the highest food availability. Complement activity depended on natural antibody levels and piglets' body condition. In the presence of CSFV (i.e., in 2005 within one area), serum samples from piglets that were repeatedly captured were used to assess whether piglet HAHL levels affected CSFV status at a later capture. The correlation between CHI and resistance to CSFV was tested using 79 HAHL measures from 23 piglets captured during a CSFV outbreak. Both natural antibodies and complement activity levels measured at a given time correlated negatively to the subsequent probability of becoming viremic. Finally, capture-mark-recapture models showed that piglets with medium/high average complement activity, independently of their age, were significantly less at risk of becoming viremic and more likely to develop a specific immune response than piglets with low complement activity. Additionally, piglets with high average complement activity showed the highest survival prospects. This study provides evidence linking CHI to individual fitness within a natural mammal population. The results also highlight the potential of HAHL assays to explore the dynamics and co-evolution between wildlife mammal hosts and blood-borne parasites interacting with the CHI. [ABSTRACT FROM AUTHOR]

African swine fever (ASF) is one of the most important diseases in Suidae due to its significant health and socioeconomic consequences and represents a major threat to the European pig industry, especially in the absence of any available treatment or vaccine. In fact, with its high mortality rate and the subsequent trade restrictions imposed on affected countries, ASF can dramatically disrupt the pig industry in afflicted countries. In September 2018, ASF was unexpectedly identified in wild boars from southern Belgium in the province of Luxembourg, not far from the Franco-Belgian border. The French authorities rapidly commissioned an expert opinion on the risk of ASF introduction and dissemination into metropolitan France. In Europe, the main transmission routes of the virus comprise direct contact between infected and susceptible animals and indirect transmission through contaminated material or feed. However, the seasonality of the disease in some pig farms in Baltic countries, including outbreaks in farms with high biosecurity levels, have led to questions on the possible involvement of arthropods in the transmission of the virus. This review explores the current body of knowledge on the most common arthropod families present in metropolitan France. We examine their potential role in spreading ASF—by active biological or mechanical transmission or by passive transport or ingestion—in relation to their bio-ecological properties. It also highlights the existence of significant gaps in our knowledge on vector ecology in domestic and wild boar environments and in vector competence for ASFV transmission. Filling these gaps is essential to further understanding ASF transmission in order to thus implement appropriate management measures. [ABSTRACT FROM AUTHOR]

African swine fever is a highly lethal hemorrhagic fever of Suidae, threatening pig production globally. Suidae can be infected by different ways like ingestion of contaminated feed, direct contact with infected animals or fomites, and biting by infected soft tick bites. As already described, European soft ticks (Ornithodoros erraticus and Ornithodoros verrucosus) were not able to transmit African swine fever virus by biting pigs although these ticks maintained the infectious virus during several months; therefore, the possibility for pigs to become infected through the ingestion of infected ticks was questioned but not already explored. To determine if such oral ingestion is an alternative pathway of transmission, O. erraticus ticks were infected by blood-feeding on a viremic pig infected with the European African swine fever virus strain Georgia2007/1, then frozen at zero and two months post-engorgement, then after, were embedded in the food to pigs. Pig infection was successful, with superior efficiency with ticks frozen just after the infectious blood meal. These results confirmed the potential role of O. erraticus ticks as an ASFV reservoir and demonstrated the efficiency of non-conventional pathways of transmission. [ABSTRACT FROM AUTHOR]

Ornithodoros soft ticks are the only known vector and reservoir of the African swine fever virus, a major lethal infectious disease of Suidae. The co-feeding event for virus transmission and maintenance among soft tick populations has been poorly documented. We infected Ornithodoros moubata, a known tick vector in Africa, with an African swine fever virus strain originated in Africa, to test its ability to infect O. moubata through co-feeding on domestic pigs. In our experimental conditions, tick-to-tick virus transmission through co-feeding failed, although pigs became infected through the infectious tick bite. [ABSTRACT FROM AUTHOR]

Pseudorabies (PR), also known as Aujeszky's disease, is an economically important disease for the pig industry. It has been eradicated in domestic pigs in many European countries, including France, but its causative agent—Suid Herpesvirus 1—is still circulating in wild boars. The risk of endemic PR in wild fauna lies in reintroducing the virus among domestic pigs and transmitting it to other mammals, especially hunting dogs for which the disease is rapidly fatal. As such infections are regularly reported in France, this study genetically characterized canine PR virus strains in the country to obtain information on their diversity and evolution. Partial sequencing of the glycoprotein C-encoding gene from 55 virus strains isolated from dogs between 2006 and 2018 showed that 14 strains belonged to genotype I-clade A and another 38 to genotype I-clade B, two clades usually reported in Western Europe. More surprisingly, three strains were found to belong to genotype II, suggesting an Asian origin. Genotype I-clade A strains exhibited the highest diversity as five geographically segregated genogroups were identified. [ABSTRACT FROM AUTHOR]

Most of the microorganisms living in a symbiotic relationship in different animal body sites (microbiota) reside in the gastrointestinal tract (GIT). Several studies have shown that the microbiota is involved in host susceptibilities to pathogens. The fecal microbiota of domestic and wild suids was analyzed. Bacterial communities were determined from feces obtained from domestic pigs (Sus scrofa) raised under different conditions: specific-pathogen-free (SPF) pigs and domestic pigs from the same bred, and indigenous domestic pigs from a backyard farm in Kenya. Secondly, the fecal microbiota composition of the African swine fever (ASF) resistant warthogs (Phacochoerus africanus) from Africa and a European zoo was determined. African swine fever (ASF) is a devastating disease for domestic pigs. African animals showed the highest microbial diversity while the SPF pigs the lowest. Analysis of the core microbiota from warthogs (resistant to ASF) and pigs (susceptible to ASF) showed 45 shared OTUs, while 6 OTUs were exclusively present in resistant animals. These six OTUs were members of the Moraxellaceae family, Pseudomonadales order and Paludibacter, Anaeroplasma, Petrimonas, and Moraxella genera. Further characterization of these microbial communities should be performed to determine the potential involvement in ASF resistance. [ABSTRACT FROM AUTHOR]

Animal diseases constitute a continuing threat to animal health, food safety, national economy, and the environment. Among those, African swine fever (ASF) is one of the most devastating viruses affecting pigs and wild suids due to the lack of vaccine or effective treatment. ASF is endemic in countries in sub-Saharan Africa, but since its introduction to the Caucasus region in 2007, a highly virulent strain of ASF virus (ASFV) has continued to circulate and spread into Eastern Europe and Russia, and most recently into Western Europe, China, and various countries of Southeast Asia. Given the importance of this disease, this review will highlight recent discoveries in basic virology with special focus on proteomic analysis, replication cycle, and some recent data on genes involved in cycle progression and viral–host interactions, such as I215L (E2 ubiquitin-conjugating enzyme), EP402R (CD2v), A104R (histone-like protein), QP509L, and Q706L (RNA helicases) or P1192R (Topoisomerase II). Taking into consideration the large DNA genome of ASFV and its complex interactions with the host, more studies and new approaches are to be taken to understand the basic virus–host interaction for ASFV. Proteomic studies are just paving the way for future research. [ABSTRACT FROM AUTHOR]