Inhibition of African swine fever virus infection by genkwanin.

African swine fever virus (ASFV) is the causative agent of an economically important disease of pigs for which no effective vaccines or antiviral drugs are available. Recent outbreaks in EU countries and China have highlighted the critical role of antiviral research in combating this disease. We have previously shown that apigenin, a naturally occurring plant flavone, possesses significant anti-ASFV activity. However, apigenin is practically insoluble in highly polar solvents and it occurs typically in derivative forms in plants. Here we screened several commercially available apigenin derivatives for their ability to inhibit ASFV Ba71V strain in Vero cells. Among them, genkwanin showed significant inhibition of ASFV, reducing viral titer from 6.5 ±â€¯0.1 to 4.75 ±â€¯0.25 log TCID/ml in a dose-dependent manner (IC50 = 2.9 µM and SI = 205.2). Genkwanin reduced the levels of ASFV early and late proteins, as well as viral DNA synthesis. Our further experiments indicated that genkwanin is able to inhibit ASFV infection at entry and egress stages. Finally, genkwanin displayed potent antiviral activity against highly virulent ASFV isolate currently circulating in Europe and China, emphasizing its value as candidate for antiviral drug development.

Genistein inhibits African swine fever virus replication in vitro by disrupting viral DNA synthesis.

African swine fever virus (ASFV) is the causal agent of a highly-contagious and fatal disease of domestic pigs, leading to serious socio-economic consequences in affected countries. Once, neither an anti-viral drug nor an effective vaccines are available, studies on new anti-ASFV molecules are urgently need. Recently, it has been shown that ASFV type II topoisomerase (ASFV-topo II) is inhibited by several fluoroquinolones (bacterial DNA topoisomerase inhibitors), raising the idea that this viral enzyme can be a potential target for drug development against ASFV. Here, we report that genistein hampers ASFV infection at non-cytotoxic concentrations in Vero cells and porcine macrophages. Interestingly, the antiviral activity of this isoflavone, previously described as a topo II poison in eukaryotes, is maximal when it is added to cells at middle-phase of infection (8 hpi), disrupting viral DNA replication, blocking the transcription of late viral genes as well as the synthesis of late viral proteins, reducing viral progeny. Further, the single cell electrophoresis analysis revealed the presence of fragmented ASFV genomes in cells exposed to genistein, suggesting that this molecule also acts as an ASFV-topo II poison and not as a reversible inhibitor. No antiviral effects were detected when genistein was added before or at entry phase of ASFV infection. Molecular docking studies demonstrated that genistein may interact with four residues of the ATP-binding site of ASFV-topo II (Asn-144, Val-146, Gly-147 and Leu-148), showing more binding affinity (-4.62 kcal/mol) than ATP4- (-3.02 kcal/mol), emphasizing the idea that this viral enzyme has an essential role during viral genome replication and can be a good target for drug development against ASFV.

Pathomorphology of the brain in the acute form of African swine fever

The brains of 10 infected pigs were examined for histopathology and presence of African swine fever virus (ASFV) DNA ASFV infection induces inflamed meninges, cerebral edema and vascular thrombosis, as well as subdural hematomas. Slight tension in the dura mater, flattening of the gyri and narrowing of the sulci were also observed at four days post infection (dpi). Enlarged perivascular spaces were detected for most vessels of the brain after three to four dpi. Considerable lymphocytic infiltration of the brain tissue was observed at the terminal stage of disease. ASFV was present in all investigated areas of brain beginning from three to four dpi. The isolated virus do not differ from the used in present study Georgia 2007 strain.

Evidence of hemolysis in pigs infected with highly virulent African swine fever virus.

AIM: The research was conducted to understand more profoundly the pathogenetic aspects of the acute form of the African swine fever (ASF). MATERIALS AND METHODS: A total of 10 pigs were inoculated with ASF virus (ASFV) (genotype II) in the study of the red blood cells (RBCs), blood and urine biochemistry in the dynamics of disease. RESULTS: The major hematological differences observed in ASFV infected pigs were that the mean corpuscular volume, mean corpuscular hemoglobin, and hematocrits were significantly decreased compared to controls, and the levels of erythropoietin were significantly increased. Also were detected the trends of decrease in RBC count at terminal stages of ASF. Analysis of blood biochemistry revealed that during ASF development, besides bilirubinemia significantly elevated levels of lactate dehydrogenase, and aspartate aminotransferase were detected. Analysis of urine biochemistry revealed the presence of bilirubinuria, proteinuria during ASF development. Proteinuria, especially at late stages of the disease reflects a severe kidney damage possible glomerulonefritis. CONCLUSION: The results of this study indicate the characteristics of developing hemolytic anemia observed in acute ASF (genotype II).