The experimental QIV showed good immunogenicity and an acceptable safety profile.

Anthrax caused by Bacillus anthracis is a fatal zoonotic disease with a high lethality and poor prognosis. Inhalational anthrax is the most severe of the three forms of anthrax. The currently licensed commercial human anthrax vaccines require a complex immunization procedure for efficacy and have side effects that limit its use in emergent situations. Thus, development of a better anthrax vaccine is necessary. In this study, we evaluate the potency and efficacy of aerosolized intratracheal (i.t.) inoculation with recombinant protective antigen (rPA) subunit vaccines against aerosolized B. anthracis Pasteur II spores (an attenuated strain) challenge in a B10.D2-Hc0 mouse (deficient in complement component C5) model. Immunization of rPA in liquid, powder or powder reconstituted formulations via i.t. route conferred 100% protection against a 20× LD50 aerosolized Pasteur II spore challenge in mice, compared with only 50% of subcutaneous (s.c.) injection with liquid rPA. Consistently, i.t. inoculation of rPA vaccines induced a higher lethal toxin (LeTx) neutralizing antibody titer, a stronger lung mucosal immune response and a greater cellular immune response than s.c. injection. Our results demonstrate that immunization with rPA dry powder vaccine via i.t. route may provide a stable and effective strategy to improve currently available anthrax vaccines and B10.D2-Hc0 mice challenged with B. anthracis attenuated strains might be an alternative model for anthrax vaccine candidate screening.

Clarifying changes in the immune microenvironment caused by vaccination is crucial for the development and application of vaccines. In this study, we analyzed seroconversion of antibodies, 12 key cytokines, and 34 lymphocyte subsets at three time points (D-1, D14, and D42) around vaccination and differences between two inactivated vaccines (Sinopharm and Sinovas) to understand the immune response induced by inactivated vaccines in the real world. The results showed that 62.5% and 75% of the participants achieved neutralizing antibody seroconversion on D14 and D42, respectively. After vaccination, IL-5 and IL-6 increased, and INF-γ decreased. IL6, IL-1B, INF-γ, IL-8, and IL-12p70 showed statistical significance in the comparison of different groups. In terms of lymphocyte subsets, CD3 +, CD56 +, CD3 + CD8 +, CD8 + CD71 +, and CD56 + CD71 + showed upward trend, while CD19 +, CD4 + CD8 +, CD8 + CD45RA +, CD4 + HLA-DR +, CD8 + HLA-DR +, and CD8 + CD38 + showed downward trend. Additionally, we found certain differences between the two vaccines in neutralizing antibodies, cytokines, and lymphocyte subsets. This research is a clinical observation on the immune response after vaccination through detecting various immune indicators, which showed that the inactivated vaccines induced both humoral immunity by producing neutralizing antibodies and cellular immunity. The cellular immunity induced by these two vaccines was a Th2-biased response, and it may also lead to a mild Th1-type response.

HypervirulentKlebsiella pneumoniae(hvKp) can cause life-threatening community-acquired infections among healthy young individuals and is thus of concern for global dissemination. In this study, a mouse model of acute primary hvKp pneumonia was establishedviaaerosolized intratracheal (i.t.) inoculation, laying the foundation for conducting extensive studies related to hvKp. Subsequently, a time-course transcriptional profile was created of the lungs from the mouse model at 0, 12, 24, 48 and 60 hours post-infection (hpi) using RNA Sequencing (RNA-Seq). RNA-Seq data were analyzed with the use of Mfuzz time clustering, weighted gene co-expression network analysis (WGCNA) and Immune Cell Abundance Identifier for mouse (ImmuCellAI-mouse). A gradual change in the transcriptional profile of the lungs was observed that reflected expected disease progression. At 12 hpi, genes related to acute phase inflammatory response increased in expression and lipid metabolism appeared to have a pro-inflammatory effect. At 24 hpi, exacerbation of inflammation was observed and active IFN-γ suggested that signaling promoted activation and recruitment of macrophages occurred. Genes related to maintaining the structural integrity of lung tissues showed a sustained decrease in expression after infection and the decrease was especially marked at 48 hpi. TNF, IL-17, MAPK and NF-kB signaling pathways may play key roles in the immunopathogenesis mechanism at all stages of infection. Natural killer (NK) cells consistently decreased in abundance after infection, which has rarely been reported in hvKp infection and could provide a new target for treatment. GenesSaa1andSlpiwere significantly upregulated during infection. BothSaa1, which is associated with lipopolysaccharide (LPS) that elicits host inflammatory response, andSlpi, which encodes an antimicrobial protein, have not previously been reported in hvKp infections and could be important targets for subsequent studies. To t our knowledge, this paper represents the first study to investigate the pulmonary transcriptional response to hvKp infection. The results provide new insights into the molecular mechanisms underlying the pathogenesis of hvKp pulmonary infection that can contribute to the development of therapies to reduce hvKp pneumonia.

Pulmonary anthrax is the most fatal clinical form of anthrax and currently available injectable vaccines do not provide adequate protection against it. Hence, next-generation vaccines that effectively induce immunity against pulmonary anthrax are urgently needed. In the present study, we prepared an attenuated and low protease activity Bacillus anthracis strain A16R-5.1 by deleting five of its extracellular protease activity-associated genes and its lef gene through the CRISPR-Cas9 genome editing system. This mutant strain was then used to formulate a lethal toxin (LeTx)-free culture supernatant extract (CSE) anthrax vaccine, of which half was protective antigen (PA). We generated liquid, powder, and powder reconstituted formulations that could be delivered by aerosolized intratracheal inoculation. All of them induced strong humoral, cellular, and mucosal immune responses. The vaccines also produced LeTx neutralizing antibodies and conferred full protection against the lethal aerosol challenges of B. anthracis Pasteur II spores in mice. Compared to the recombinant PA vaccine, the CSE anthrax vaccine with equal PA content provided superior immunoprotection against pulmonary anthrax. The preceding results suggest that the CSE anthrax vaccine developed herein is suitable and scalable for use in inhalational immunization against pulmonary anthrax.