ABSTRACT
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.
ABSTRACT
The facultative intracellular pathogen Listeria monocytogenes is of major veterinary importance in small ruminants. Nevertheless, details of L. monocytogenes interactions with cells of small ruminants are not fully established. To study the potential of L. monocytogenes to infect sheep cells, we used the finite sheep kidney cell line (shKEC), which was infected with the wild-type L. monocytogenes strain EGDe. The invasion efficiency was 0.015 ± 0.004%. The invasion factor InlB was critically important for invasion, and inlB gene deletion almost prevented L. monocytogenes invasion into shKEC cells. Comparison of the potential of phylogenetically defined InlB isoforms to restore the invasive phenotype of the EGDeΔinlB strain demonstrated that although all InlB isoforms restored invasion of the EGDeΔinlB strain into shKEC cells, the InlB isoforms typical of highly virulent ruminant strains of the clonal complexes CC1 and CC7 were more efficient than isoforms typical of CC2 and CC9 strains (which are less virulent toward ruminants) in supporting invasion. Listeria monocytogenes effectively multiplied with a doubling of time in about 90 min after they entered the sheep cells. Intracellular bacteria moved using the well-known actin polymerization mechanism. Cell-to-cell spreading was restricted to the infection of a few tens of neighboring cells for 7 days. Overall, the obtained results demonstrated that (i) InlB is required for invasion into sheep cells, (ii) InlB isoforms might be important for hypervirulence of certain clonal groups toward ruminants, and (iii) L. monocytogenes effectively multiplies in ovine cells once entered.
ABSTRACT
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.
