STRUCTURAL AND ULTRA-STRUCTURAL ORGANIZATION OF LYMPH GLANDS OF WILD PIGS IN CONDITIONS OF AFRICAN SWINE FEVER (EXPERIMENTAL STUDY)

The authors presents data on the structural and ultra-structural organization of the immune system organs (lymph glands) of wild pigs in terms of experimental reproduction of the African Swine Fever (ASF) with highly virulent field isolate of the second genotype ASF virus circulating on the Russian Federation territory

African Swine Fever Virus, Siberia, Russia, 2017.

African swine fever (ASF) is arguably the most dangerous and emerging swine disease worldwide. ASF is a serious problem for the swine industry. The first case of ASF in Russia was reported in 2007. We report an outbreak of ASF in Siberia, Russia, in 2017

Identification of T-cell epitopes in African swine fever virus CD2v and C-type lectin proteins.

African swine fever (ASF) is an emerging disease threat for the swine industry worldwide. No ASF vaccine is available, and progress is hindered by lack of knowledge concerning the extent of ASF virus (ASFV) strain diversity and the viral antigens conferring type-specific protective immunity in pigs. Previously, we demonstrated that ASFV serotype-specific proteins CD2v (EP402R) and/or C-type lectin (EP153R) are important for protection against homologous ASF infection. Here, we identified six discrete T-cell epitope regions present on CD2v and C-type lectin using IFN-γ ELISpot assay and PBMCs from ASF immune animals, indicating cellular reactivity to these proteins in the context of ASFV infection and protective immunity. Notably, three of the epitope regions map to previously described serotype-specific signature regions of these proteins. Improved understanding of ASFV protective antigens, relevant epitopes and their diversity in nature will facilitate ASFV subunit vaccine design and development

Seroimmunotyping of African swine fever virus

The extreme genetic and immunobiological heterogeneity exhibited by the African swine fever virus (ASFV) has been a significant impediment in the development of an efficacious vaccine against this disease. Consequently, the lack of internationally accepted protocols for the laboratory evaluation of candidate vaccines has become a major concern within the scientific community. The formulation of such protocols necessitates the establishment of a consensus at the international level on methods for the determination of homologous and heterologous isolates/strains of ASFV. The present article provides a comprehensive description of biological techniques employed in the classification of ASFV by seroimmunotypes. These techniques involve a holistic evaluation of ASFV isolates/strains based on their antigenic properties as determined by the hemadsorption inhibiting test (HAdI) using type-specific sera and an immunological test (IT) conducted on pigs inoculated with attenuated strains. The article outlines the methods for setting up the HAdI test, an IT on pigs, and the processes involved in the acquisition of type-specific serums for the HAdI test. It is pertinent to note that the definitive classification of seroimmunotype can only be ascertained after conducting an IT on pigs. The findings from the HAdI test or the phylogenetic analysis of the EP402R gene should be considered preliminary in nature

Identifying climate-sensitive infectious diseases in animals and humans in Northern regions.

BACKGROUND: General knowledge on climate change effects and adaptation strategies has increased significantly in recent years. However, there is still a substantial information gap regarding the influence of climate change on infectious diseases and how these diseases should be identified. From a One Health perspective, zoonotic infections are of particular concern. The climate in Northern regions is changing faster than the global average. This study sought to identify climate-sensitive infectious diseases (CSIs) of relevance for humans and/or animals living in Northern regions. Inclusion criteria for CSIs were constructed using expert assessments. Based on these principles, 37 potential CSIs relevant for Northern regions were identified. A systematic literature search was performed in three databases using an explicit stepwise approach to determine whether the literature supports selection of these 37 potential CSIs. RESULTS: In total, 1275 nominated abstracts were read and categorised using predefined criteria. Results showed that arthropod vector-borne diseases in particular are recognised as having potential to expand their distribution towards Northern latitudes and that tick-borne encephalitis and borreliosis, midge-borne bluetongue and the parasitic infection fasciolosis can be classified as climate-sensitive. Many of the other potential CSIs considered are affected by extreme weather events, but could not be clearly classified as climate-sensitive. An additional literature search comparing awareness of climate influences on potential CSIs between 1997-2006 and 2007-2016 showed an increase in the number of papers mentioning effects of climate change. CONCLUSIONS: The four CSIs identified in this study could be targeted in a systematic surveillance programme in Northern regions. It is evident that climate change can affect the epidemiology and geographical range of many infectious diseases, but there were difficulties in identifying additional CSIs, most likely because other factors may be of equal or greater importance. However, climate-ecological dynamics are constantly under change, and therefore diseases may fall in or out of the climate-sensitive definition over time. There is increasing awareness in the literature of the effects of climate change on infectious diseases over time

Genetic and antigenic diversity of African swine fever virus.

African swine fever virus (ASFV) is the only known DNA arbovirus, and the ability to replicate efficiently in both insect and mammalian cells is encoded in its viral genome. Despite having a relatively low overall genomic mutation rate, ASFV demonstrates genetic diversity in certain genes and complexity in gene content in other genomic regions, indicating that ASFV may exploit multiple mechanisms for diversification and acquire new phenotype characteristics. ASFV antigenic diversity is reflected in the ability to type cross-protective viruses together into serogroups, largely based on antibody-mediated inhibition of hemadsorption. Here we review ASFV genetic signatures of ASFV type specificity, genome variability, and the hemadsorption as a means of defining virus antigenic type, and how these may be used toward defining antigenic and phenotypic diversity that is problematic for development of vaccine solutions to ASF

Search for additional tests for immunobiological evaluation of the candidate vaccines against African swine fever.

The spread of African swine fever (ASF) in Eurasia has forced a return to the development of live vaccines based on naturally or experimentally attenuated strains of the virus including those resulting from genetic manipulations. This process includes evaluation of the immunomodulating properties of the vaccines. In this report we provide our assessment of two tests for immunobiological evaluation of a candidate live vaccine against ASF from the attenuated ASF virus (ASFV) strain KK-202: (i) investigation of the effect of the attenuated ASFV strain KK-202 on the protectiveness of the vaccine ASFV strain FK-32/135 and a vaccine against classical swine fever (CSF) from the strain LK-VNIIVViM; (ii) determination of the phagocytic activity of blood neutrophils in pigs inoculated with ASFV strains differing in virulence. A simultaneous or sequential inoculation of attenuated strain KK-202 (seroimmunotype II) and vaccine strain FK-32/135 (seroimmunotype IV) into pigs resulted in the loss of protection against the virulent strain France-32 (seroimmunotype IV). Following the simultaneous or sequential inoculations of the ASFV strain KK-202 and the CSF virus (CSFV) vaccine produced from the strain LK-VNIIVViM, the neutralizing antibody titers against the CSFV observed in the experimental groups (after vaccination and after the challenge infection with the virulent CSFV strain Shimen) were not different from those found in animals of the control group. The phagocytic activity of blood neutrophils was shown to increase from 30% in the norm to 50%-94% depending on the virulence of the ASFV strains inoculated into pigs. The results of this work demonstrate the ability of the attenuated ASFV strains to modulate the development of the cellular link of protective immunity without negative impact on the humoral immune response. The informative value of the described immunobiological tests in vivo and in vitro seems to be a more preferable alternative in comparison to the commonly used in vitro tests, which do not always correlate with the development of protection against ASF

SEROTYPE-SPECIFIC AND HAEMADSORPTION PROTEIN OF THE AFRICAN SWINE FEVER VIRUS

This review presents comparative results of simultaneously conducted studies on proteins responsible for the haemadsorption and serotype-specific properties of African swine fever virus (ASFV). An ASFV gene EP402R (or LMW8-DR) encoding protein CD2v homologous to murine, human or porcine T-cell adhesive receptor was found. The CD2v was shown to be directly involved into a haemadsorption process, and expressed in ASFV-infected cells as a glycoprotein with a molecular weight of approximately 105-110 kDa. In the presence of a glycosylation inhibitor, tunicamycin, its molecular weight is about 42 kDa. In ASFV-infected cells labeled with 3H-glucosamine or 14C-sodium acetate, a virus-specific major glycoprotein with a molecular weight of 110-140 kDa (gp 110-140) was identified using radioimmunoprecipitation assay. Using ASFV reference strains belonging to seroimmunotypes I-IV and the corresponding antisera active in haemadsorption inhibition assay (HADIA), we determined that gp 110-140 defines the serotype specificity. Genotyping on the basis of the genetic locus encoding the CD2v and a C-type lectin protein also showed a concurrence with the grouping of ASFV isolates and strains based on their seroimmunotypes. Immunization of pigs with the gp 110-140 within liposomes, or a recombinant haemagglutinin (CD2v) protected 67 to 100% of animals from death due to their subsequent infection with homologous virulent ASFV strains. Based on the physico-chemical and biological characteristics of the gp 110-140 and CD2v it is suggested that they are one and the same virus-specific glycoprotein crucial for induction of the immunological protection against ASF. Key words: ASFV; seroimmunotypes; serotype; glycoproteins; gp 110-140; CD2v; protectivity   SEROTIPNO-SPECIFIČEN IN HEMADSORPCIJSKI PROTEIN VIRUSA AFRIŠKE PRAŠIČJE KUGE A.D Povzetek: Pregledni članek predstavlja primerjavo rezultatov sočasno izvedenih raziskav o beljakovinah, ki so pomembne za hemadsorpcijo in serotipno specifične lastnosti virusa afriške prašičje kuge (ASFV; iz angl. african swine fever virus). Pri virusu ASFV je bil odkrit gen EP402R (imenovan tudi LMW8-DR), ki kodira beljakovino CD2v, ki je homologna glodavskemu, človeškemu in prašičjemu T-celičnemu adhezivnemu receptorju. Pokazalo se je, da je CD2v neposredno vpletena v proces hemadsorpcije in je izražena v celicah, okuženih z ASFV kot glikoprotein z molekulsko maso okrog 105-110 kDa. V prisotnosti zaviralca glikozilacije tunicamicina je njegova molekulska masa približno 42 kDa. V celicah, okuženih z ASFV, označenih s 3H-glukozaminom ali 14C-natrijevim acetatom, je bil s testom radioimunoprecipitacije ugotovljen virusno specifični osrednji glikoprotein z molekulsko maso 110-140 kDa (gp 110-140). Z uporabo referenčnih sevov ASFV, ki pripadajo seroimunotipom I-IV, in ustreznim antiserumom, ki so bili aktivni pri preizkusu zaviranja hemadsorpcije (HADIA), smo ugotovili, da gp 110-140 določa specifičnost serotipa. Genotipizacija na osnovi genskega lokusa, ki kodira CD2v in C-tip lektinske beljakovine, je pokazala soizražanje s skupino izolatov in sevov ASFV na podlagi njihovih seroimunotipov. Imunizacija prašičev z gp 110-140 v liposomih ali z rekombinantnim hemaglutininom (CD2v) je zaščitila od 67 do 100 odstotkov živali pred smrtjo zaradi njihove naknadne okužbe z virulentnimi sevi ASFV. Na podlagi fizikalno-kemičnih in bioloških značilnosti beljakovin gp 110-140 in CD2v menimo, da gre za isti virusni glikoprotein, ki je ključnega pomena za vzpodbuditev imunološke zaščite pred ASF. Ključne besede: ASFV; seroimunotipi; serotip; glikoproteini; gp 110-140; CD2v; zaščita

The attenuated ASFV strains MK-200 and FK-32/135 as possible models for investigation of protective immunity by ASFV infection.

African swine fever (ASF) is an infectious disease of domestic and wild pigs of all breeds and ages, with the acute form of the disease being characterized by high fever, hemorrhages in the reticuloendothelial system and a high mortality rate. Registered safe and efficacious ASF vaccines are not available. The development of experimental ASF vaccines, particularly live attenuated, have considerably intensified in the last years. There is much variability in experimental approaches undertaken by laboratories attempting to develop first generation vaccines, rendering it difficult to interpret and make comparisons across trials. ASF virus (ASFV) genotyping does not fully correlate with available cross-protection data and may be of limited value in predicting cross-protective vaccine efficacy. Recently, ASFV strains were assigned to a respective nine groups by seroimmunotype (from I to IX): in vivo the grouping is based on results of cross protection of pigs survived after their infection with a virulent strain (bioassay), while in vitro this grouping is based on hemadsorption inhibition assay (HADIA) data. Here we demonstrate the antigenic and protective properties of two attenuated ASFV strains MK200 and FK-32/135. Pronounced differences in the HADIA and in immunological test in animals allow us to consider them and the corresponding reference virulent strains of the ASFV of Mozambique-78 (seroimmunotype III, genotype V) and France-32 (seroimmunotype IV, genotype I) as useful models for studying the mechanisms of protective immunity and evaluation of the candidate vaccines