Presence and survival of African swine fever virus in leeches.

This research is focused on the study of African swine fever virus (ASFV) survival in the leech Hirudo medicinalis. To detect the infection route of the virus in leeches, two introduction methods were used: blood-feeding from infected swine hosts and exposure to ASFV-contaminated water (leeches cultivated with ASFV). This study found that the survival of ASFV in leeches was much longer than that in leech-free medium. The persistent presence of the virus in leeches and leech excretion was detected in both groups. The virus excreted from both groups of leeches in the terminal stages of the experiment was able to induce productive infection in porcine alveolar macrophages. In an attempt to understand ASFV, transmission to pigs was conducted through the ingestion of leech-cultivated water and leeches that had fed on ASFV-infected animals or that were cultivated environmentally with the virus. The ingestion of some samples at 60-80 days after cultivation demonstrated successful ASFV transmission via per os infection. In conclusion, leeches can serve as a possible reservoirs for ASFV in the absence of its main hosts - pigs and some ticks of the genus Ornithodoros.

The epidemiological status of African swine fever in domestic swine herds in the Tavush Province region, Armenia.

KEEN The factors associated with the spread and persistence of African swine fever (ASF) in the Caucasus region remain to be fully identified. It is assumed that large naive populations of domestic free-ranging and wild pigs are critical to disease transmission and maintenance. Nonetheless, 11 years since its epidemic introduction into the region in 2007, ASF virus (ASFV) is still circulating, suggesting that an endemic cycle has been established based on contact between free-ranging domestic pigs and wild pigs, and that native Ornithodoros ticks probably serve as reservoirs for the virus. Therefore, research is required to gather information on the epidemiological status of ASF in the Caucasus region, focusing particularly on understanding modes of ASFV spread and persistence in this new virus environment. The authors established an ASFV survey targeting domestic pigs in the Tavush province of northern Armenia, an area of the country considered to be at high risk of disease incursion/occurrence. All tested samples collected for this survey were negative for ASF. The probability of observing no reactors by antibody enzyme-linked immunosorbent assay in a sample of this size (n = 1,506) from a population with an estimated disease prevalence of 1% is very low (< 0.0001). Therefore, it is possible but very unlikely for ASFV to be present among domestic pigs in the Tavush province region.

Les facteurs associés à la propagation de la peste porcine africaine (PPA) dans le Caucase et à sa persistance restent en grande partie à élucider. On suppose que la présence de populations naïves de porcs domestiques en liberté et de porcs sauvages joue un rôle déterminant dans la transmission et le maintien de la maladie. Néanmoins, 11 ans après son introduction épidémique dans la région en 2007, le virus de la peste porcine africaine (VPPA) est toujours présent, ce qui laisse penser qu'un cycle s'est installé à la faveur des contacts entre les porcs domestiques en liberté et les porcs sauvages, les tiques autochtones Ornithodoros faisant probablement office de réservoir viral. Des études sont donc nécessaires pour recueillir des informations sur le statut épidémiologique de la PPA dans le Caucase et plus particulièrement pour comprendre les modalités de la propagation et de la persistance du VPPA dans ce nouvel environnement. Les auteurs rapportent les résultats d'une enquête épidémiologique sur le VPPA conduite chez les porcs domestiques de la province du Tavush, au nord de l'Arménie, zone considérée comme présentant un risque élevé d'incursion et d'émergence de la maladie. Les échantillons prélevés à cette fin ont tous donné des résultats négatifs au test de détection de la PPA. La probabilité qu'un échantillon de cette taille (n = 1 506) ne donne aucune réaction positive à l'épreuve ELISA de détection d'anticorps dans une population pour laquelle la prévalence de la maladie est estimée à 1 % est extrêmement faible (< 0,0001). On peut en conclure que la présence du VPPA parmi les porcs domestiques de la région du Tavush est possible, mais très improbable.

Aún no están perfectamente identificados los factores que intervienen en la propagación y persistencia de la peste porcina africana (PPA) en la región del Cáucaso. Se presupone que la existencia de grandes poblaciones de cerdos salvajes y cerdos domésticos en libertad que no han estado expuestas previamente al patógeno es un factor crucial en la transmisión y el mantenimiento de la enfermedad. Sin embargo, 11 años después de su penetración epidémica en la región, en 2007, el virus de la PPA aún sigue en circulación, hecho que parece apuntar al establecimiento de un ciclo endémico mediado por el contacto entre cerdos domésticos en libertad y cerdos salvajes y también a la probable función de la garrapata autóctona Ornithodoros como reservorio del virus. Por consiguiente, es necesario investigar para reunir información sobre la situación epidemiológica de la PPA en la región del Cáucaso, procurando especialmente aprehender las modalidades de propagación y persistencia del virus en este nuevo entorno. Los autores estudiaron la presencia del virus de la PPA específicamente en cerdos domésticos de la provincia de Tavush, al norte de Armenia, una zona del país considerada muy expuesta al riesgo de incursión o manifestación de la enfermedad. Todas las muestras obtenidas y analizadas para el estudio dieron resultado negativo a la PPA. La probabilidad de no detectar con ELISA ningún ejemplar con anticuerpos en una muestra de tal tamaño (n = 1 506), tomada de una población con una prevalencia de la enfermedad que según los cálculos es del 1%, resulta ínfima (<0,0001). Es por lo tanto posible, pero harto improbable, que el virus de la PPA esté presente en los cerdos domésticos de la zona de la provincia de Tavush.

Third wave of African swine fever infection in Armenia: Virus demonstrates the reduction of pathogenicity.

AIM: First cases of clinically uncommon African swine fever (ASF), caused by virus genotype II are described in this article. These cases occurred in Armenia, Tavush region, Dilijan municipality in 2011. The aim of this study was to identify and describe the new pathogenic forms of ASF in Armenia. MATERIALS AND METHODS: The isolation and identification of ASF virus (ASFV) were carried out using conventional techniques. Clinical signs of infection were recorded daily. Gross anatomical pathology characteristics were observed during routine postmortem examinations. Blood and serum were obtained by puncture of the jugular vein using a vacutainer system. RESULTS: The presence of ASFV DNA in the spleens was confirmed by polymerase chain reaction. Sequenced sections of p72 showed phylogenetic identity to genotype 2. The pathology exhibits unusual manifestations of the main disease. The unusual form of ASF demonstrates characteristics of a subacute form of the disease, with the possibility of conversion to a chronic form. Decreased lethality, low level of hemorrhages, and absence of severe pancytopenia in smears from spleen, lymph nodes, and blood are common features of the new form of ASF. Unlike severe thrombocytopenia in the typical ASF, the unusual form exhibited moderate or minor decrease of this feature. Despite a moderate decrease in hemadsorption titers, the unusual pattern of the disease was characterized by viremia and the presence of the virus in the visceral organs, including the brain. CONCLUSION: Our data allow assuming that new nosological form of ASF (genotype II) may present as a transitional form of the disease with the possibility of chronization.

IL-23/IL-17/G-CSF pathway is associated with granulocyte recruitment to the lung during African swine fever.

The interleukin (IL)-23/IL-17 pathway plays a crucial role in various forms of inflammation but its function in acute African swine fever (ASF) is not well understood. Thus, in this study, we aimed to find out whether IL-23/IL-17/G-CSF is released in acute ASF and what function it may have. The present study revealed that the production of IL-17 and IL-23 were significantly increased in the sera of ASFV infected pigs. Using ELISA, we found that the serum levels of IL-23 and IL-17 have overexpressed in ASF virus infected pigs compared with healthy controls. The levels of IL-17 and IL-23 increase in the early stages and the levels of G-CSF and C - reactive protein in the later stages of ASF. Simultaneously, with the increase of the levels of IL-23/IL-17 extravasation of granular leukocytes in the tissue (diapedesis) is observed. Diapedesis can explain the neutropenia that we identified previously in the terminal stages of ASF. The increase in serum levels of IL-23/IL-17 is preceded by enhanced migration of neutrophils in tissues, and the last one is preceded by neutropenia. The increase in serum levels of G-CSF has compensatory nature, directed on stimulation of proliferation of granulocytes. Taken together, our results revealed an overexpression of the IL-23/IL-17 axis in the ASF virus infected pigs, suggesting that it may be a crucial pathway in the diapedesis at ASF.

Interferon status and white blood cells during infection with African swine fever virus in vivo.

African swine fever virus (ASFV) is the causative agent of African swine fever that is the significant disease of domestic pigs, with high rates of mortality. ASFV is double-stranded DNA virus whose genes encode some proteins that are implicated in the suppression of host immune response. In this study, we have modeled in vivo infection of ASFV for determination of interferon (IFN) status in infected pigs. We measured the level of IFN-α, -ß and -γ by enzyme-linked immunosorbent assay and showed that the level of IFN-α sharply decreased during infection. Unlike IFN-α, the level of IFN-ß and -γ increased from the 2nd and 4th days post-infection, respectively. Also, we analyzed the population dynamics of peripheral white blood cells of infected pigs due to their important role in host immune system. We showed that the atypical lymphocytes appeared after short time of infection and this result is in accordance with our previous study done in vitro. At the last day of infection about 50% of the total white blood cells were destroyed, and the remaining cells were represented mainly by small-sized lymphocytes, reactive lymphocytes and lymphoblasts.

Interaction of Paramecium caudatum and Picornaviruses.

In our paper we have researched the relationship between picornaviruses (poliovirus, foot-and-mouth disease virus and encephalomyocarditis virus) and Ciliata (Paramecium caudatum). We show that the number of Paramecium in medium sharply increased during coincubation with picornaviruses within 2-5 days. This cannot be explained only by the fact that viruses were nutrient source for Paramecium because in case of inactivated viruses the number of infusorians in medium increased a little. At the same time the titer of viruses harshly decreased whereas in the control group, which is free of Paramecium, the fall of titer was little. Picornaviruses were eliminated from medium if only living Parameciums were present in medium. After 7-9 days of coincubation only a few number of viruses were liberated from destroyed Parameciums. These results will be especially useful for management of reservoirs of picornaviruses in water and prevention of diseases.

Phenotypic and cytologic studies of lymphoid cells and monocytes in primary culture of porcine bone marrow during infection of African swine fever virus.

We have modeled in vitro infection of African swine fever virus (ASFV) in primary unstimulated cells of the porcine bone marrow and have studied the phenotypical changes in the population of porcine lymphoid cells by cytophotometry. Monocytes and large-sized lymphocytes completely vanished in 72 h of infection which is result of high sensitivity of those cells to ASFV. We describe DNA synthesis in monocytes at 24 h post infection. Cytophotometry of the uninfected cells revealed the few number of atypical lymphocytes and lymphoblasts after 72 h of cultivation; whereas in viral infected cultures, atypical cells appeared in large quantity (about 14%) with 24 h. Most of atypical lymphocytes and lymphoblasts had altered nucleus, and only a small number of atypical cells had additional nucleus. The cytophotometry of main and additional nuclei showed that DNA content didn't exceed diploid standard which indicates that the additional nuclei were consequence of fragmentation of nuclei in lymphocytes.

G(E(p))/G(M(p)) ratio by polarization transfer in e-->p --> ep-->

The ratio of the proton's elastic electromagnetic form factors, G(E(p))/G(M(p)), was obtained by measuring P(t) and P(l), the transverse and the longitudinal recoil proton polarization, respectively. For elastic e-->p-->ep-->, G(E(p))/G(M(p)) is proportional to P(t)/P(l). Simultaneous measurement of P(t) and P(l) in a polarimeter provides good control of the systematic uncertainty. The results for the ratio G(E(p))/G(M(p)) show a systematic decrease as Q2 increases from 0.5 to 3.5 GeV2, indicating for the first time a definite difference in the spatial distribution of charge and magnetization currents in the proton.