L. monocytogenes is a widespread facultative intracellular pathogen. The range of natural hosts that supporting L. monocytogenes persistence in the environment has not been fully established yet. In this study, we were interested in the potential of L. monocytogenes to infect cells of bats, which are being increasingly recognized as a reservoir for microorganisms that are pathogenic to humans and domestic animals. A stable epithelial cell line was developed from the kidneys of Pipistrellus nathusii, a small bat widely distributed across Europe. The wild-type L. monocytogenes strain EGDe infected this cell line with an invasion efficiency of 0.0078 ± 0.0009%. Once it entered bat cells, L. monocytogenes doubled within about 70 minutes. When L. monocytogenes lacked either of the major invasion factors, InlA and InlB, invasion efficiency decreased by a factor of 10 and 25 respectively (p < 0.000001). The obtained results suggest that bat epithelial cells are susceptible to L. monocytogenes infection and that L. monocytogenes invasion of bat cells depends on the major invasion factors InlA and InlB. These results constitute the first report on in vitro studies of L. monocytogenes infection in bats.

African swine fever virus causes hemorrhagic disease in swine. Attenuated strains are reported in Africa, Europe, and Asia. Few studies on the diagnostic detection of attenuated ASF viruses are available. Two groups of pigs were inoculated with an attenuated ASFV. Group 2 was also vaccinated with an attenuated porcine reproductive and respiratory syndrome virus vaccine. Commercially available ELISA, as well as extraction and qPCR assays, were used to detect antibodies in serum and oral fluids (OF) and nucleic acid in buccal swabs, tonsillar scrapings, OF, and blood samples collected over 93 days, respectively. After 12 dpi, serum (88.9% to 90.9%) in Group 1 was significantly better for antibody detection than OF (0.7% to 68.4%). Group 1′s overall qPCR detection was highest in blood (48.7%) and OF (44.2%), with the highest detection in blood (85.2%) from 8 to 21 days post inoculation (dpi) and in OF (83.3%) from 1 to 7 dpi. Group 2′s results were not significantly different from Group 1, but detection rates were lower overall. Early detection of attenuated ASFV variants requires active surveillance in apparently healthy animals and is only reliable at the herd level. Likewise, antibody testing will be needed to prove freedom from disease.

The African swine fever virus (ASFV) is the cause of a recent pandemic that is threatening the global pig industry. The virus infects domestic and wild pigs and manifests with a variety of clinical symptoms, depending on the strain. No commercial vaccine is currently available to protect animals from this virus, but some attenuated and recombinant live vaccine candidates might be effective against the disease. This article describes the immunobiological characteristics of one such candidate—the laboratory-attenuated ASFV strain, Katanga-350—which belongs to genotype I. In this study, we assessed clinical signs and post-mortem changes, the levels of viremia and the presence of viral DNA caused by injection of ASF virus strains Katanga-350, Lisbon-57, and Stavropol 08/01. Intramuscular injection of this strain protected 80% of pigs from a virulent strain of the same genotype and seroimmunotype (Lisbon-57). At least 50% of the surviving pigs received protection from subsequent intramuscular infection with a heterologous (genotype II, seroimmunotype VIII) virulent strain (Stavropol 08/01). Virus-specific antibodies were detectable in serum and saliva samples between 8–78 days after the first inoculation of the Katanga-350 strain (the observational period). The results suggested that this strain could serve as a basis for the development of a recombinant vaccine against ASF viruses belonging to seroimmunotype I.

A b s t r a c tLumpy skin disease is an economically significant transmissible infectious disease with mortatity rate from 4 to 95 %. Purebred animals are more susceptible to this infection, most seriously the disease occurs in young animals, not enough well-fed individuals, lactating cows. In Russia, the disease is registered since 2015. To eradicate this infection, it is necessary to study all components of the epizootic process. Currently, the studies on the pathogenicity of lumpy skin disease virus for sheep and goats and wild ruminants are insufficient to assess the role of such animals in the transmission of the virus. We estimated for the first time that lumpy skin disease virus isolated from cattle in the Republic of North Ossetia-Alania in 2015 is pathogenic for sheep. The causative agent was identified by sequencing the GPCR gene. In the experiment with 1.5-month-old lambs (n = 4), intravenous and intradermal administration of the suspension of the biopsy samples from sick cows caused the formation of nodules on the skin at the sites of virus inoculation. Nodules were benign in nature, after two weeks it formed the scabs and separated from the skin. On the skin in places of formation nodules there were small scars. The genome of lumpy skin disease virus was detected by real-time PCR in blood samples collected from 9 to 17 days post infection, and in the oral swabs collected from 17 to 27 days post infection. The duration of viremia in lambs ranged from 3 to 8 days. The presence of infectious virus was confirmed by isolation of virus on continuous cell culture of sheep kidney. The clinical signs of the disease corresponded to 2 points calculated in accordance with clinical scoring system within the range from 0 («no visible response») to 10 points («severe generalization, requiring slaughter»). After euthanasia the samples of the liver, popliteal lymph node, lungs and spleen were collected to test for the presence of the viral genome. The genome of the virus was detected only in the lung and lymph nodes. So, our results confirm literature data about pathogenicity of lumpy skin disease virus for sheep. Potentially, sheep can be involved in the epizootic process of lumpy skin disease as source of virus transmitted by blood feeding arthropods.

This article presents the results of a study on the susceptibility of laboratory animals to the lumpy skin disease virus (LSDV). Mice weighing 15–20 g, hamsters weighing 40–60 g, guinea pigs weighing 600–1200 g, and rabbits weighing 2.5–3 kg were used in this study. Nodules were observed on the skin of rabbits and hamsters at the sites of inoculation. The virus was isolated from the affected skin areas in cell culture and examined using real-time PCR, indicating its tropism for animal skin. The production of anticapripoxvirus antibodies was detected using the neutralization reaction, starting from 10 days after infection in mice, 27 days in rabbits, and 14 days in hamsters. Some laboratory animals exhibited multiple skin nodules. This indicates that these animal species may play a role in maintaining the epizootic process.