ASF Virus Research Articles

Afrykański pomór świń i interwencyjny odstrzał dzika – podstawy prawa unijnego i krajowego

The ASF virus has been spreading among wild boars for over a decade in several European countries, including Poland. As a result, there are quitenumerous infections among domestic pigs as well. Therefore, numerous EU and Member State regulations have been published in this respect anda biosecurity procedure has been introduced. One of its elements is to hunt wild boars in areas vulnerable to the ASF virus. The increase in the numberof infections among wild boars and the appearance of numerous outbreaks of this disease among pigs prompted the Polish authorities to allow a significant increase in the amount of wild boar hunting. This decision aroused debate on the legitimacy of such a solution. The purpose of this study is toanalyse the provisions of EU and Polish law regarding the legitimacy of an increase in the amount of wild boar hunting in Poland.

Research Advances in African Swine Fever Virus (minireview)

African swine fever remains one of most economically threatened diseases that has been hurting to the swine industry in Ukraine since 2014 and in China since 2018. African swine fever is an acute, highly lethal infectious disease caused by African swine fever virus, which has occurred and spread in many countries around the world, causing a catastrophic blow to the swine industry in the affected countries. ASFV is characterized of large genome, encoding 150-200 proteins, including variety of immunoregulatory proteins, which can resist immunity. African swine fever virus mainly enters pigs through the respiratory and digestive tract. The target cells infected are mainly mononuclear-macrophages, and the receptor is still unclear. Research on the development of diagnostic techniques and tests related to African swine fever are continuing and their proper using is crucial. There are many studies on African swine fever virus vaccines, including inactivated vaccines, attenuated vaccines, subunit vaccines and genetic vaccines. But so far these vaccines have not been able to protect domestic pigs from African swine fever virus infection. The article mainly reviews the researches of ASF virus, epidemiology, pathogenesis, diagnostic techniques and attempts to vaccine`s develop, that provides theoretical basis for the prevention and control of ASF.

Risk of African swine fever virus introduction into the United States through smuggling of pork in air passenger luggage

African swine fever causes substantial economic losses in the swine industry in affected countries. Traditionally confined to Africa with only occasional incursions into other regions, ASF began spreading into Caucasian countries and Eastern Europe in 2007, followed by Western Europe and Asia in 2018. Such a dramatic change in the global epidemiology of ASF has resulted in concerns that the disease may continue to spread into disease-free regions such as the US. In this study, we estimated the risk of introduction of ASF virus into the US through smuggling of pork in air passenger luggage. Results suggest that the mean risk of ASFV introduction into the US via this route has increased by 183.33% from the risk estimated before the disease had spread into Western Europe or Asia. Most of the risk (67.68%) was associated with flights originating from China and Hong Kong, followed by the Russian Federation (26.92%). Five US airports accounted for >90% of the risk. Results here will help to inform decisions related to the design of ASF virus surveillance strategies in the US.

AFRICAN SWINE FEVER VIRUS: USE OF GENETIC MARKERS IN ANALYSIS OF ITS ROUTES OF SPREAD

At present no effective measures for specific prevention and treatment of African swine fever have been developed. The control strategy for the disease is designed for rapid diagnosis of infected animals with subsequent slaughter and decontamination (stamping out). The present review deals with current epidemic situation for African swine fever and examines features of the virus genomics and genetic differentiation of the isolates. The Russian Federation has been ASF-infected since 2007. Since that time the disease has been one of the key problems in pig farming of this country inflicting great economic losses, both directly and indirectly. The disease continues to spread. In January 2014 African swine fever was introduced to Lithuania, then pervaded Poland, Latvia, Estonia, Romania, Belgium and Moldova. Since 2018 the disease outbreaks have been reported in Asia (China, Vietnam, and Mongolia). Specific structure of the virus and long genome, encoding genes with unknown function, and circulation of 24 genotypes and 9 serotypes of the virus hinder the development of ASF vaccine. The article shows that the use of many specific genetic markers during determination of relationship and study of pathways of ASF virus global spread is the most accurate method.

Dynamics of antibodies production after experimental challenge with ASF virus

Dynamics of antibodies production after experimental challenge with ASF virus

Особенности течения африканской чумы у свиней, инфицированных изолятами вируса АЧС, выделенными в Российской Федерации

Особенности течения африканской чумы у свиней, инфицированных изолятами вируса АЧС, выделенными в Российской Федерации

Attenuated and non-haemadsorbing (non-HAD) genotype II African swine fever virus (ASFV) isolated in Europe, Latvia 2017.

A non-haemadsorbing (non-HAD) ASF virus (ASFV) genotype II, namely Lv17/WB/Rie1, was isolated from a hunted wild boar in Latvia in 2017. Domestic pigs experimentally infected with the non-HAD ASFV developed a nonspecific or subclinical form of the disease. Two months later, these animals were fully protected when exposed to other domestic pigs infected with a related virulent HAD genotype II ASFV.

ANALYSIS OF CHANGES IN AFRICAN SWINE FEVER VIRUS GENETIC STRUCTURE AND BIOLOGICAL PROPERTIES DURING ADAPTATION TO CONTINUOUS CELL CULTURE

Functions of many African swine fever virus genes and multigene family members have not been yet understood. In particular, no virus genes directly associated with pig virulence have been identifed. Identifcation of such genes will enable preparation of deletion mutant ASF virus strains as well as development and testing of pilot safe vaccines based on the said virus strains. Comparative analysis of the virus biological characteristics and detection of differences in its genome structure affecting certain phenotypic features is a main method used for the virus basic pathogenicity and immunogenicity examination. The most interesting and effective approach to addressing this problem is an analysis of changes in the gene structure during ASF virus adaptation to replication in continuous cell culture. The said factors have made continuous cell culture-adapted variant ASF virus preparation necessary. Variant viruses with modifed biological features were prepared during adaptation of ASFV Odintsovo 02/14 isolate to replication in CV-1 cell culture. Lethality level was 16.7% when pigs were infected with adapted variant virus at 30th passage and survived animals became resistant to reinfection with homologous virulent ASFV Arm07 isolate. It should be noted that the virus passage in non-permissive cell culture up to 30 serial passages did not result in changes in its genotype; however, a large 3,000 bp deletion similar to that one in continuous Vero-cell culture-adapted BA71V strain genome appeared in right terminal variable region of the genome.

Analysis of the African Swine Fever Virus Immunomodulatory Proteins

Molecular epidemiology of viral infections traditionally based on the analysis of changes in individual genes or genetic markers. The analysis of the African swine fever virus (ASFV) genes encoding immunomodulatory proteins is an important tool for studying the diversity and evolution of the virus. In this work, we carried out a structural and phylogenetic analysis of the ASF virus immunomodulatory proteins 5EL (A238L gene), I14L (Dp71L gene), K11L (I329L gene). The degree of nucleotide substitutions of the ASFV concatenated genes A238L, I329L and Dp71L revealed purifying (stabilizing) selection at the nucleotide sequences level. The variability characteristic of the selected group of ASFV genes is of great interest for the genetic differences search in immunomodulatory proteins. The sequencing results of the A238L, I329L and Dp71L genes and their phylogenetic analysis showed that these genes are conservative among a large group of ASFV genes. The I329L gene is a genetic marker of common origin. The East African strains (Genotype X) of Dp71L gene have two forms: a long (184 amino acids) and a short (from 70 to 72 amino acids) and is formed by fusion of the 13L and 14L. All ASF virus Russian isolates isolated in 2016–2017 were identical to the reference strain ASFV/Georgia/wb/2007. Characterization of variability 5EL protein, I14L, K11L may be serve to identify target sites in the ASFV genome and to develop vaccines. The obtained data allow to evaluate the genetic diversity of the ASFV immunomodulatory proteins and the dynamics of their evolution, to predict the possible participation of the A238L, I329L and Dp71L genes in the virulence of various ASFV strains.

Rynek mięsa wieprzowego w Polsce w obliczu afrykańskiego pomoru świń (ASF)

Celem badania jest ocena oddziaływania wirusa afrykańskiego pomoru świń ASF (African Swine Fever) na rozwój i funkcjonowanie rynku mięsa wieprzowego w Polsce. Wirus ten pojawił się w Polsce w lutym 2014 roku u dzików, a następnie w lipcu 2014 roku u świń. Badanie obejmuje lata 2014-2018, czyli okres występowania wirusa ASF w Polsce. Do końca lipca 2018 roku odnotowano 182 przypadki ASF u świń i ponad 2,6 tysiąca u dzików w czterech województwach wschodniej i centralnej Polski, a największe skupisko tej choroby zlokalizowane jest w województwie lubelskim. Pojawienie się wirusa ASF negatywnie wpłynęło na rynek mięsa wieprzowego w Polsce, skutkując ograniczeniami w eksporcie tego mięsa, kosztami likwidacji ognisk choroby i bioasekuracji. Mimo tych trudności produkcja mięsa wieprzowego w Polsce w latach 2014-2018 odznaczała się tendencją wzrostową, a eksport jedynie w pierwszym roku występowania ASF obniżył się, w kolejnych latach, w związku z dywersyfikacją rynków zbytu, odnotowano jego wzrost. Do badania zastosowano metodę opisową i proste analizy statystyczne.

Biological Properties and Molecular-Genetic Characteristics of African Swine Fever Virus Isolated in Various Regions of Russia in 2016–2017

African swine fever virus (ASFV) isolated in 2016–2017 from domestic pigs and wild boars in eight regions of the Russian Federation has comparable biological characteristics: it is virulent, causes the death of animals with signs of acute and overactive forms without the manifestation of a complete symptom complex of clinical and pathologic symptoms, possesses hemadsorption and accumulates in the initial (swine leukocytes, SBM) and transplantable (A4C2/9k) cell cultures in titres 5.5–7.5 and 3.5–5.25 log HAU/50cm3, respectively. The studied isolates belong to the eighth serotype and the second genotype. According to these indicators, the ASF virus is comparable with the virus isolates circulating in Russia since 2007.

CLONING OF GENES ENCODING TRANSMEMBRANE PROTEINS AND PROTEINS RESPONSIBLE FOR AFRICAN SWINE FEVER VIRUS VIRULENCE

Results of cloning X69R, A179L, E248R, I215L and DP96R genes of ASF virus Krasnodar 07/17 isolate and analysis of their nucleotide sequences are presented. Obtained clones were added to the previously constructed clone library comprising clones of 8 genes of Krasnodar 06/12 isolate. Clones containing X69R, A179L, E248R, I215L and DP96R genes of ASF virus Krasnodar 07/17 isolate will be used for recombinant protein obtaining and testing for their effect on in vitro virus reproduction and their role in the virus infectivity, level of clinical manifestations and virulence. Prokaryotic vector, pJET1.2/ blunt, was used. Thus, the clone library available at the FGBI “ARRIAH” Reference Laboratory for African swine fever was supplemented by pJET1.2-X69R, pJET1.2-A179L, pJET1.2-E248R, pJET1.2-I215L and pJET1.2-DP96R plasmid constructions containing 5 genes of ASF virus Krasnodar 07/17 isolate. Proportion of cloned virus genes was 3.01% of Krasnodar 07/17 isolate genome, hence, total amount of the clone library has reached 7.82%.

CLONING OF GENES ENCODING TRANSMEMBRANE PROTEINS AND PROTEINS RESPONSIBLE FOR AFRICAN SWINE FEVER VIRUS VIRULENCE

Results of cloning X69R, A179L, E248R, I215L and DP96R genes of ASF virus Krasnodar 07/17 isolate and analysis of their nucleotide sequences are presented. Obtained clones were added to the previously constructed clone library comprising clones of 8 genes of Krasnodar 06/12 isolate. Clones containing X69R, A179L, E248R, I215L and DP96R genes of ASF virus Krasnodar 07/17 isolate will be used for recombinant protein obtaining and testing for their effect on in vitro virus reproduction and their role in the virus infectivity, level of clinical manifestations and virulence. Prokaryotic vector, pJET1.2/ blunt, was used. Thus, the clone library available at the FGBI “ARRIAH” Reference Laboratory for African swine fever was supplemented by pJET1.2-X69R, pJET1.2-A179L, pJET1.2-E248R, pJET1.2-I215L and pJET1.2-DP96R plasmid constructions containing 5 genes of ASF virus Krasnodar 07/17 isolate. Proportion of cloned virus genes was 3.01% of Krasnodar 07/17 isolate genome, hence, total amount of the clone library has reached 7.82%.

POLUDANUM’S INFLUENCE ON REPRODUCTIVE AND RESPIRATORY SYNDROME, TRANSMISSIBLE GASTROENTERITIS AND AFRICAN SWINE FEVER VIRUSES IN PRIMARY AND CONTINUOUS CELL CULTURES

Today studies of the influence of interferon synthesis inducer on human and animal body is a topical issue. Interferon synthesis inducers are substances of natural or artificial origin stimulating production of body’s own interferon. One of the synthetic inducers of interferon is Poludanum. It is used for stimulation of cell immunity which is capable of preventing infection and disease development and has antiviral and immunomodulatory effect. Poludanum mainly stimulates induction of α-interferon and, to a lesser extent, β- and γ-interferon in cells and tissues which prevent virus reproduction in a cell. The paper presents results of poludanum’s influence on reproduction of some porcine viruses in primary and continuous cell cultures by induction of interferon synthesis and other cytokines lowering the level of cell infection. As a result of performed tests it was found out that there is a link between introduction of interferon inducer and change in the PRRS, TGE, ASF virus reproduction. There was detected a high level of Poludanum’s interferon inducing activity in pig testicular primary cell cultures and spleen compared to the continuous pig embryo kidney (SPEV) and rhesus monkey kidney (MARC-145) cell lines. Poludanum’s interferon inducing activity was moderate for MARC-145 cells and it was not determined for SPEV.

Biological properties of African swine fever virus Odintsovo 02/14 isolate and its genome analysis

We performed analysis of the biological properties of African swine fever virus (ASF) isolate Odintsovo 02/14. Domestic pigs were inoculated with 50 (low) or 5000 (high) hemadsorbing doses (HAD) of the virus via intranasal (IN) or intramuscular (IM) routes, to investigate the pathogenesis of ASF virus Odintsovo 02/14 isolate. Our results indicated that filtered 10% spleen suspension of ASFV isolate Odintsovo 02/14 induced an acute disease in pigs, resulting in 100% mortality rate. For cultural viral suspension (3rd passage), produced in a PBM cells mortality rate was 85.7%. We also present an analysis of the complete genome of African swine fever virus (ASF) Odintsovo 02/14 isolate. It is 189 333 nucleotide long and contains more than 160 open reading frames (ORFs). Complete nucleotide sequence of the genome of Odintsovo 02/14 isolate was obtained using pyrosequencing method and used to determine differences between the nucleotide sequences in the genomes of Odintsovo 02/14 and Georgia 01/2007. The genome of ASF virus Odintsovo 02/14 contains substitutions, insertions and deletions in genes encoding structural, membrane, and regulatory proteins, DNA reparation enzymes, host immune response evasion proteins, and MGF genes. The intergenic region I73R/I329L of Odintsovo 02/14 isolate contains 10-nucleotide long tandem repeat sequence, missing in Georgia 01/2007.

Effect of gamma radiation on the course of African swine fever infection

This report analyzes some data on the effect of management of animals γ-irradiated with doses causing mild, moderate, or severe acute radiation sickness and pigs being the carriers of some virulent ASF virus pathogens of serotypes I and IV (namely, strains 0–77 and Diamang) as observed 2 h or 3 to 34 days after the irradiation procedure had started. When the animals were radiated combined with their infection with virulent ASF virus strains, a more severe course of the infection was observed, whereas the infection development with a background of radiation injury made the radiation sickness more violent. The ASF virus accumulation levels in blood, organs, and/or tissues of the irradiated animals were reliably higher (namely, by approximately 1.0 to 1.5 log HAU50/cm3) than those for nonirradiated ones.

Африканська чума свиней в Україні

The spread of African swine fever in Ukraine is analyzed. During the period of 2012–2017, the disease cases of domestic and wild pigs were registered in the territory of 131 administrative districts of 23 regions. Wild pigs are not the primary source of spreading the ASF virus. Within four years (2008–2011), the ASF, through the southern and central territories of Russia, reached the northeastern regions of Ukraine. However, the first case of the disease in the Zaporizhye region (2012) showed that the cause of the African swine fever in the territory of Ukraine was not wild pigs, but humans. The ASF was found at a considerable distance from the area of the spread of the disease. In the north-eastern regions of Ukraine, the disease was detected only in 2014. This disease could result from penetration of infected wild pigs from the territory of the neighboring state into Ukraine, in particular into Luhansk-, Chernihiv-, and Sumy regions. Evidence of this is the fact that of the 16 cases in 2014 – 12 cases were recorded in wild pigs and four – in the private sector. As of April 2017, out of 208 detected cases, only 14% was identified among wild pigs due to the small number of the species in Ukraine compared to other European countries. In 16.7% of 478 administrative districts of Ukraine, wild pigs are not found in game hunting grounds; in 2.7% of the districts area, the density of animals is less than 0.1 individual per 1000 ha, and in 65.0% of the area it is insignificant: from 0.1 to 1.4 individuals. Intense hunting (13–22% harvesting of the game stock) during 2015–2016 led to a decrease in the numbers by 33.8% in 2017. As of 2017, the number of wild pigs is more than 40 thousand individuals. Most cases with fever were recorded in the period from July to March. More than 18% of cases of pig disease were detected in August. In general, in summer, about 30% of diseases were recorded, during the autumn – about 27%, in winter – 34%, in spring – only 9%. Wild pigs were most often infected in the autumn-winter period, not recorded – in April, June and September. Over 65% of animal disease cases were detected during the hunting season. The major cause of the spread of African swine fever are humans. Localization of the disease among wild pigs can be achieved through rational use and management of the species population.

A longitudinal survey of African swine fever in Uganda reveals high apparent disease incidence rates in domestic pigs, but absence of detectable persistent virus infections in blood and serum.

BackgroundAfrican swine fever (ASF) is a fatal, haemorrhagic disease of domestic pigs, that poses a serious threat to pig farmers and is currently endemic in domestic pigs in most of sub-Saharan Africa. To obtain insight into the factors related to ASF outbreaks at the farm-level, a longitudinal study was performed in one of the major pig producing areas in central Uganda. Potential risk factors associated with outbreaks of ASF were investigated including the possible presence of apparently healthy ASF-virus (ASFV) infected pigs, which could act as long-term carriers of the virus. Blood and serum were sampled from 715 pigs (241 farms) and 649 pigs (233 farms) to investigate presence of ASFV and antibodies, during the periods of June-October 2010 and March-June 2011, respectively. To determine the potential contribution of different risks to ASF spread, a questionnaire-based survey was administered to farmers to assess the association between ASF outbreaks during the study period and the risk factors.ResultsFifty-one (21 %) and 13 (5.6 %) farms reported an ASF outbreak on their farms in the previous one to two years and during the study period, respectively. The incidence rate for ASF prior to the study period was estimated at 14.1 per 100 pig farm-years and 5.6 per 100 pig farm-years during the study. Three pigs tested positive for ASFV using real-time PCR, but none tested positive for ASFV specific antibodies using two different commercial ELISA tests.ConclusionsThere was no evidence for existence of pigs that were long-term carriers for the virus based on the analysis of blood and serum as there were no seropositive pigs and the only three ASFV DNA positive pigs were acutely infected and were linked to outbreaks reported by farmers during the study. Potential ASF risk factors were present on both small and medium-scale pig farms, although small scale farms exhibited a higher proportion with multiple potential risk factors (like borrowing boars for sows mating, buying replacement from neighboring farms without ascertaining health status, etc) and did not implement any biosecurity measures. However, no risk factors were significantly associated with ASF reports during the study.

Эффективность различных методов выращивания вируса африканской чумы свиней в гемопоэтических клетках

For African swine fever virus (ASFV) reproduction little publications are available, in particular, those concerning cultivation technologies. Moreover, the range of effective cell systems for cultivation is limited too. This report highlights the development and comparative evaluation of methods for African swine fever virus (ASFV) growth in porcine bone marrow cell (PBM) and leukocyte (PL) cultures for their efficacy. We showed the possibility of using cell suspension prepared from porcine bone marrow after its 24-hour storage at 4 to 6 °С for ASFV culture. The virus grown in the PBM cell suspension after the abovementioned storage period for porcine bone marrow had expired did not reduce its infectious activity, and accumulated with titers of 7.25 to 7.50 lg TCID 50/cm 3. The conditions for ASF virus culture in hematopoietic cells using stationary devices like KASM (a cassette unit for monolayer culture), a technique for roll-bottle culture in a circular monolayer or in a cell suspension, and biological reactors (fermentors) for a suspension culture were analyzed. When using these culture methods, ASF virus steadily accumulated in the PBM or PL cells with high titers ranging from 7.25 to 8.00 lg HAU 50/cm 3. Nevertheless, ASF virus growth in hematopoietic cell suspensions using automated reactors was found to be the most effective, technologically advanced and productive technique. In this case, the virus titers were as high as 7.50 to 8.00 lg HAU 50/cm 3. Analyzing the results of the studies we concluded that the above methods were more efficient as compared to ASFV growth in a stationary cell culture using flasks, and could be used for large scale cultivation of this biological agent in vaccinology and diagnostics of African swine fever infection.

Тhe use of membrane filters in detection of the asf virus dna in the feed compound by RT-PCR

Тhe use of membrane filters in detection of the asf virus dna in the feed compound by RT-PCR