Interleukin-18 (IL-18) is an important cytokine involved in innate and acquired immunity. In this study, we cloned the fulllength chicken IL-18 (ChIL-18) gene from specific-pathogen-free (SPF) chicken embryo spleen cells and provided evidence that the ChIL-18 gene in a recombinant plasmid was successfully expressed in chicken DT40 cells. ChIL-18 significantly enhanced gamma interferon (IFN-␥) mRNA expression in chicken splenocytes, which increased IFN-␥-induced nitric oxide (NO) synthesis by macrophages. The potential genetic adjuvant activity of the ChIL-18 plasmid was examined in chickens by coinjecting ChIL-18 plasmid and inactivated Newcastle disease virus (NDV) vaccine. ChIL-18 markedly elevated serum hemagglutination inhibition (HI) titers and anti-hemagglutinin-neuraminidase (anti-HN)-specific antibody levels, induced the secretion of both Th1-(IFN-␥) and Th2-(interleukin-4) type cytokines, promoted the proliferation of T and B lymphocytes, and increased the populations of CD3؉ T cells and their subsets, CD3 ؉ CD4 ؉ and CD3 ؉ CD8 ؉ T cells. Furthermore, a virus challenge revealed that ChIL-18 contributed to protection against Newcastle disease virus challenge. Taken together, our data indicate that the coadministration of ChIL-18 plasmid and NDV vaccine induces a strong immune response at both the humoral and cellular levels and that ChIL-18 is a novel immunoadjuvant suitable for NDV vaccination. N ewcastle disease (ND) is a serious avian disease that causes substantial economic loss and remains a major threat to the poultry industry (1, 2). Outbreaks of ND among poultry occur worldwide, and the pathogenic form of the virus is a disease listed in the World Organization for Animal Health (OIE) Terrestrial Animal Health Code and must be reported to the OIE (3), which results in severe trade limitations (4, 5). Currently, vaccination is the major tool for controlling infection by Newcastle disease virus (NDV). The NDV vaccine strains LaSota, B1, Mukteswar, and V4 are used widely in China. However, virulent NDV strains are still frequently isolated in vaccinated birds, indicating that NDV remains an ongoing threat to commercial flocks of birds (6). Therefore, it is necessary to develop more efficacious vaccines to prevent NDV infection.Many techniques have been developed to increase the immunogenicity of vaccines. Among these, cytokines are effective immunomodulators in animal models or in clinical testing (7-10). Among the large number of cytokines, interleukin-18 (IL-18) is a strong stimulator of T helper type 1 (Th1) responses and activates natural killer (NK) cells, stimulates the synthesis of other immunoactive cytokines from Th1 cells, monocytes, and NK cells, and synergizes with IL-12 in the maturation of Th1 cells and the suppression of IgE synthesis by B cells (11-13). Thus, IL-18 functions as an adjuvant (14, 15). However, depending on the cytokine environment, IL-18 may also promote Th2-type responses (16,17) and antibody formation (18).The isolation and characterization of chicken IL-18 (ChIL-18) ...

Background Salmonella enterica is regarded as a major public health threat worldwide. Salmonella secretes the novel translocated effector protein K2 (SseK2), but it is unclear whether this protein plays a significant role in Salmonella enterica Typhimurium virulence. Results A Δ sseK2 mutant of S. Typhimurium exhibited similar growth curves, adhesion and invasive ability compared with wild-type (WT) bacteria. However, deletion of sseK2 rendered Salmonella deficient in biofilm formation and the early proliferative capacity of the Δ sseK2 mutant was significantly lower than that of the WT strain. In vivo, the LD 50 (median lethal dose) of the Δ sseK2 mutant strain was increased 1.62 × 10 3 -fold compared with the WT strain. In addition, vaccinating mice with the Δ sseK2 mutant protected them against challenge with a lethal dose of the WT strain. The ability of the Δ sseK2 mutant strain to induce systemic infection was highly attenuated compared with the WT strain, and the bacterial load in the animals’ internal organs was lower when they were infected with the Δ sseK2 mutant strain than when they were infected with the WT strain. Conclusions We conclude that sseK2 is a virulence-associated gene that plays a vital role in Salmonella virulence. Electronic supplementary material The online version of this article (10.1186/s12866-019-1543-2) contains supplementary material, which is available to authorized users.

The objectives of this study are to analyse the pollution status and spatial correlation of soil heavy metals and identify natural and anthropogenic sources of these heavy metals at different spatial scales. Two hundred and twenty-four soil samples (0-20 cm) were collected and analysed for eight heavy metals (Cd, Hg, As, Cu, Pb, Cr, Zn and Ni) in soils of different land-use types in the Yangtze River Delta of Eastern China. The multivariate methods and factorial Kriging analysis were used to achieve the research objectives. The results indicated that the human and natural effects of different land-use types on the contents of soil heavy metals were different. The Cd, Hg, Cu, Pb and Zn in soils of industrial area were affected by human activities, and the pollution level of these heavy metals in this area was moderate. The Pb in soils of traffic area was affected by human activities, and eight heavy metals in soils of residential area and farmland area were affected by natural factor. The ecological risk status of eight heavy metals in soils of the whole study area was light. The heavy metals in soils showed three spatial scales (nugget effect, short range and long range). At the nugget effect and short range scales, the Cd, Hg, Cu, Pb and Zn in soils were affected by human and natural factors. At three spatial scales, the As, Cr and Ni in soils were affected by soil parent materials.

Background: Salmonella enterica serovar Typhimurium (S. Typhimurium) is an important infectious disease pathogen that can survive and replicate in macrophages. Glycolysis is essential for immune responses against S. Typhimurium infection in macrophages, and is also associated with apoptosis. S. Typhimurium secreted effector K3 (SseK3) was recently identified as a novel translated and secreted protein. However, there is no study about the role of sseK3 in the relationship between apoptosis and glycolysis in cells infected with S. Typhimurium. It is unclear whether this protein exerts a significant role in the progress of apoptosis and glycolysis in S. Typhimurium-infected macrophages. Results: Macrophages were infected with S. Typhimurium SL1344 wild-type (WT), ΔsseK3 mutant or sseK3complemented strain, and the effects of sseK3 on apoptosis and glycolysis were determined. The adherence and invasion in the ΔsseK3 mutant group were similar to that in the WT and sseK3-complemented groups, indicating that SseK3 was not essential for the adherence and invasion of S. Typhimurium in macrophages. However, the percentage of apoptosis in the ΔsseK3 mutant group was much lower than that in the WT and sseK3complemented groups. Caspase-3, caspase-8, and caspase-9 enzyme activity in the ΔsseK3 mutant group were significantly lower than in the WT group and sseK3-complemented groups, indicating that sseK3 could improve the caspase-3, caspase-8, and caspase-9 enzyme activity. We also found that there were no significant differences in pyruvic acid levels between the three groups, but the lactic acid level in the ΔsseK3 mutant group was much lower than that in the WT and sseK3-complemented groups. The ATP levels in the ΔsseK3 mutant group were remarkably higher than those in the WT and sseK3-complemented groups. These indicated that the sseK3 enhanced the level of glycolysis in macrophages infected by S. Typhimurium. Conclusions: S. Typhimurium sseK3 is likely involved in promoting macrophage apoptosis and modulating glycolysis in macrophages. Our results could improve our understanding of the relationship between apoptosis and glycolysis in macrophages induced by S. Typhimurium sseK3.