Humoral and cellular immune responses in mice against secreted and somatic antigens from a Corynebacterium pseudotuberculosis attenuated strain: Immune response against a C. pseudotuberculosis strain

Immune response of BALB/c mice infected with two strains of Corynebacterium pseudotuberculosis

This work evaluated aspects of the immune response of BALB/c mice infected with Corynebacterium pseudotuberculosis (T1 and C57). The fifteen BALB/c mice were euthanized after 70 days of infection and morphologically evaluated, also analyzing the innate and adaptive immune responses. The C57 strain induced more pronounced morphological changes than the T1 strain. There was an increase in CD4+ and CD8+ T cells identified during infection with the C57 strain. Cytokines of the inflammatory profile IL-1α and IL-6 and regulatory IL-13 and IL-10 presented significant differences. Cytokines IL-2, IL-4, INF-γ, IL-22, IL-21, and IL-27 did not differ significantly between groups. The obtained results contribute to a better understanding of the type of response and the immunological mechanisms involved during infection with different strains of C. pseudotuberculosis.

Comparative Characterization of Immune Response in Sheep with Caseous Lymphadenitis through Analysis of the Whole Blood Transcriptome

Caseous lymphadenitis (CL) is a chronic contagious disease that affects small ruminants and is characterized by the formation of pyogranulomas in lymph nodes and other organs. However, the pathogenesis of this disease and the response of the host genome to infection are not yet fully understood. This study aimed to investigate the whole blood transcriptome and evaluate differential gene expression during the later stages of CL in naturally infected ewes. The study included diseased, serologically positive (EP), exposed, serologically negative (EN) ewes from the same infected flock and healthy ewes (CN) from a different flock. RNA sequencing was performed using the Illumina NextSeq system, and differential gene expression was estimated using DESeq2 and Edge R approaches. The analysis identified 191 annotated differentially expressed genes (DEGs) in the EP group (102 upregulated and 89 downregulated) and 256 DEGs in the EN group (106 upregulated and 150 downregulated) compared to the CN group. Numerous immunoregulatory interactions between lymphoid and nonlymphoid cells were influenced in both EP and EN ewes. Immune DEGs were preferentially assigned to antigen presentation through the MHC complex, T lymphocyte-mediated immunity, and extracellular matrix interactions. Furthermore, the EP group showed altered regulation of cytokine and chemokine signaling and activation and recombination of B-cell receptors. Conversely, NF-kappa B signaling, apoptosis, and stress response were the main processes influenced in the EN group. In addition, statistically significant enrichment of the essential immune pathways of binding and uptake of ligands by scavenger receptors in EP and p53 signaling in the EN group was found. In conclusion, this study provides new insights into the disease course and host-pathogen interaction in naturally CL-infected sheep by investigating the blood transcriptome.

The Association of Bacterin and Recombinant Proteins Induces a Humoral Response in Sheep against Caseous Lymphadenitis

In this study, we investigated the capacity of the recombinant proteins SpaC, NanH, SodC, and PLD of C. pseudotuberculosis to trigger protective humoral and cellular immune responses against experimentally induced C. pseudotuberculosis infection in sheep. The antigens were produced in a heterologous system and were purified by affinity chromatography. Nine sheep were randomly divided into three groups, which were immunized as follows: Group 1 (control)—a mix of adjuvants composed of the inactivated T1 strain of C. pseudotuberculosis and commercial Montanide™ISA 61 VG (T1M); Group 2—rSpaC, rSodC, rPLD, and T1M; Group 3—rNanH, rSodC, rPLD, and T1M. All groups were immunized twice (on days 0 and 30) and challenged on day 90 of the experiment. Humoral and cellular immune responses were evaluated by Enzyme-Linked Immunosorbent Assay (ELISA) to quantify the IgG antibodies and interferon-gamma (IFN-y). Both vaccine formulations with recombinant proteins (groups 2 and 3) could induce a significant humoral IgG immune response in sheep. The proteins rSodC, rPLD, and rNanH were more immunogenic, inducing significant levels of IgG antibodies after the first dose of the vaccine or after the challenge, maintaining constant levels until the end of the experiment. However, it was not possible to differentiate between the cellular responses induced by the vaccines. This lack of effectiveness points toward the need for further studies to improve the efficacy of this subunit-based vaccine approach.

Chemokine production induced by Corynebacterium pseudotuberculosis in a murine model

Corynebacterium pseudotuberculosis is the etiological agent of caseous lymphadenitis. The main clinical sign of this disease is the development of granulomas, especially in small ruminants; however, the pathways that are involved in the formation and maintenance of these granulomas are unknown. Cytokines and chemokines are responsible for the migration of immune cells to specific sites and tissues; therefore, it is possible that chemokines participate in abscess formation. This study aimed to evaluate the induction of chemokine production by two C. pseudotuberculosis strains in a murine model. A highly pathogenic (VD57) and an attenuated (T1) strain of C. pseudotuberculosis, as well as somatic and secreted antigens derived from these strains, was used to stimulate murine splenocytes. Then, the concentrations of the chemokines CCL-2, CCL-3, CCL-4, and CCL-5 and the cytokines IL-1 and TNF were measured in the culture supernatants. The VD57 strain had a higher ability to stimulate the production of chemokines when compared to T1 strain, especially in the early stages of stimulation, which can have an impact on granuloma formation. The T1 lysate antigen was able to stimulate most of the chemokines studied herein when compared to the other antigenic fractions of both strains. These results indicate that C. pseudotuberculosis is a chemokine production inducer, and the bacterial strains differ in their induction pattern, a situation that can be related to the specific behavior of each strain.

Saponin-adjuvanted recombinant vaccines containing rCP00660, rCP09720 or rCP01850 proteins against Corynebacterium pseudotuberculosis infection in mice

PURPOSE

rCP01850, rCP09729 and rCP00660 proteins from Corynebacterium pseudotuberculosis, predicted as the three best targets to be used in vaccines against Caseous Lymphadenitis in mature epitope density (MED) analysis were tested as vaccinal targets in association to saponin as adjuvant.

METHODOLOGY

rCP00660, rCP09720 and rCP01850 were expressed in E. coli and purified for immunization assay. Balb/c mice were divided into five groups of sixteen animals each. G1 was injected with saline solution (0.9% NaCl), G2 with saponin, G3, G4 and G5 with, respectively, rCP00660, rCP09720 and rCP01850 added by saponin. Two doses were administered within a 21-days interval, and blood samples were collected for IgG quantification. Twenty-one days after the last immunization, ten mice in each group were challenged with virulent C. pseudotuberculosis MIC-6 strain, and mortality was recorded for 40 days. Meanwhile six mice in each group were used for cytokine quantification by qPCR.

RESULTS

G2, G3, G4 and G5 presented protection rates of 10, 30, 40 and 60%, respectively. In spite of levels of total IgG were higher in G4 and G5, production of IgG2a was higher than IgG1 for G5. G3, G4 and G5 presented significant high IFN-γ levels, however, only G5 showed high TNF-α while G3 and G4 showed high IL-17.

CONCLUSION

rCP01850 added by saponin was able to protect efficiently mice against C. pseudotuberculosis challenge, and to induce high IgG, IFN-γ and TNF-α levels. In spite of rCP00660 and rCP09720 had not same adequate protection levels, significant IgG, IFN-γ, and IL-17 levels and further studies aiming to improve protection rates should be conducted.

Vaccines for caseous lymphadenitis: up-to-date and forward-looking strategies

Caseous lymphadenitis (CLA) is an infectious chronic disease responsible for economic losses in sheep and goat breeding worldwide. CLA has no effective treatment, evidencing the vaccination schedule as the best control strategy. Although some commercial vaccines have been available, none of them provides total protection, which is sometimes insufficient and does not reach the same efficiency when compared in sheep and goats. They also have questionable safety levels and side effects. In light of this, several experimental vaccines are in development in order to improve safety, reproducibility, and protective immune response against the etiologic agent of CLA, Corynebacterium pseudotuberculosis. In this review, we discussed aspects as antigen, adjuvant, routes of administration, protection level, and animal models used in CLA vaccine development, as well the challenges and future perspectives. KEY POINTS: Caseous lymphadenitis (CLA) does not have an appropriate commercial vaccine. Different experimental vaccines are in development aiming to protect against Corynebacterium pseudotuberculosis. An ideal vaccine for CLA is necessary for the disease control.

The combination of Corynebacterium pseudotuberculosis recombinant proteins rPLD, rCP01850 and rCP09720 for improved detection of caseous lymphadenitis in sheep by ELISA

Corynebacterium pseudotuberculosis is the causative agent of caseous lymphadenitis (CLA), a chronic disease of sheep and goats. Current methods for CLA diagnosis cannot identify all infected animals; therefore, the development of an improved diagnosis is essential. We evaluated recombinant phospholipase D (rPLD) protein individually or combined with rCP01850 or rCP09720 proteins for the detection of CLA in sheep. A total of 40 positive and 25 negative sera samples were analysed by ELISA using the recombinant proteins. ELISA using rPLD (E1), rPLD+rCP01850 (E2) and rPLD+rCP09720 (E3) showed 90, 92.5 and 97.5 % sensitivity and 92, 72 and 92 % specificity, respectively. The area under the receiver operating characteristic curves for E1, E2 and E3 was 0.925, 0.882 and 0.990, respectively. ELISA using rPLD +rCP09720 demonstrated the best sensitivity and specificity. Thus, the combination of these recombinant proteins in indirect ELISA has the potential for the diagnosis of CLA in sheep.

Biogenic Silver Nanoparticles as a Post-surgical Treatment for Corynebacterium pseudotuberculosis Infection in Small Ruminants

Caseous lymphadenitis (CL) is an infectious and zoonotic disease characterized by the development of granulomas in the lymph nodes and internal organs of small ruminants. The etiological agent of this disease is Corynebacterium pseudotuberculosis, a Gram-positive and facultative intracellular bacterium. The conventional treatment for CL consists of drainage and chemical cauterization of the lesions using a 10% iodine solution. However, this type of treatment is not effective, due to iodine's cytotoxic profile and low antibacterial activity. Currently, silver nanoparticles (AgNPs) can be seen as an alternative treatment for CL due to their antimicrobial activity and wound healing effects. Therefore, the present study aimed to evaluate AgNPs as a post-surgical treatment for CL. Twenty-nine goats and sheep with clinical signs of CL were selected. Surgical intervention was performed to excise the caseous lesions. To treat the lesions, an ointment formulation based on AgNP mixed with natural waxes and oils was used in the experimental group, and the conventional treatment with 10% iodine was used in the control group. Bacteria were isolated from the excised caseous material. The animals were observed for 8 weeks after the surgical treatment, and blood samples were taken weekly. The surgical wounds of sheep treated with AgNP healed faster, and the surgical wound area was smaller during the observation period; the latter effect was also observed in goats. AgNP-treated animals also had less purulent discharge and less moisture in the surgical wounds. The AgNP-treated animals had lower leukocyte counts and lower titers of anti-C. pseudotuberculosis antibodies. There was no statistically significant difference between the groups with regard to the hemogram results. The results of the susceptibility testing of C. pseudotuberculosis strains (T1, 1002, FRC41, and VD57 strains) and clinical isolates to AgNPs showed growth inhibition, even at low concentrations. It can be concluded that post-surgical treatment of CL using the AgNP-based ointment may be a promising tool in the control of CL, through faster healing, decreased wound contamination, and no apparent toxic effects.

Recombinant M. bovis BCG expressing the PLD protein promotes survival in mice challenged with a C. pseudotuberculosis virulent strain

The aim of this study was to evaluate the survival of mice inoculated with M. bovis BCG Pasteur recombinant expressing the PLD protein and challenged with a C. pseudotuberculosis virulent strain. Four groups were immunized with a sterile 0.9% saline solution (G1), 10⁶ CFU of M. bovis BCG Pasteur (G2), 10⁶ CFU of M. bovis BCG/pld (G3) or 10⁶ CFU of M. bovis BCG/pld with a booster with rPLD (G4) and challenged with 10⁴ CFU of C. pseudotuberculosis MIC-6 strain. The highest survival rate of 88% was observed in G4, followed by 77% in G3 and 66% in G2. A significant statistical difference was observed in the levels of cytokines IFN-γ and IL-10 in vaccinated groups (G3 and G4) when compared with the control group (G1) (p < 0.05). The results seem promising as the recombinant vaccine elicited a cellular immune response and provided significant survival after a high virulent challenge.

Evaluation of specific and non-specific immune response of four vaccines for caseous lymphadenitis in sheep challenged

Background

Caseous lymphadenitis (CLA) is a serious disease affects sheep and goat, caused by Corynebacterium pseudotuberculosis. Due to it is non-treatable disease, so the effective preventive vaccines are considered a significant way to combat the disease. All strains of C. pseudotuberculosis have several virulence factors that associated with their cell invasion, survival, and proliferation such as phospholipase D (PLD), outer lipid coat, and secreted proteases.

Aim

The present study was directed to perform a comparative innate and acquired immune response assessment of different four vaccine formulas to evoke protection against induced (CLA) challenge in sheep.

Materials and Methods

Negative ELISA (free of CLA) 15 local breed male (Balady) sheep were divided into five groups, each has received a different vaccine while the control has received saline buffer. The first vaccine composed of toxoid PLD alone the second composed of toxoid PLD with bacterin (formalinkilled bacteria), the third vaccine composed of toxoid PLD plus covaccine 8, while the fourth one composed of toxoid PLD plus locally produced polyvalent clostridial vaccine. The specific immune response was evaluated through lymphocyte proliferation assay using ELISA BrdU kit, while the non-specific response was estimated by superoxide anion production and lysozyme activity assays.

Results

The study revealed that PLD toxoid could evoke the highest specific immune response, showing a stimulation index (9.12%). On the other hand, combined toxoid ↱PLD with bacterin followed by PLD toxoid showed a significant increase in the non-specific innate immune response.

Conclusion

The present study indicated that the toxoid PLD alone vaccine was most efficient and provided innate and acquired immune response in animals against CLA.

Association of Corynebacterium pseudotuberculosis recombinant proteins rCP09720 or rCP01850 with rPLD as immunogens in caseous lymphadenitis immunoprophylaxis

Caseous lymphadenitis (CLA) is a chronic disease responsible for significant economic losses in sheep and goat breeding worldwide. The treatment for this disease is not effective, and an intense vaccination schedule would be the best control strategy. In this study, we evaluated the associations of rCP09720 or rCP01850 proteins from Corynebacterium pseudotuberculosis with recombinant exotoxin phospholipase D (rPLD) as subunit vaccines in mice. Four experimental groups (10 animals each) were immunized with a sterile 0.9% saline solution (G1), rPLD (G2), rPLD + rCP09720 (G3), and rPLD + rCP01850 (G4). The mice received two doses of each vaccine at a 21-day interval and were challenged 21 days after the last immunization. The animals were evaluated daily for 40 days after the challenge, and mortality rate was recorded. The total IgG production level increased significantly in the experimental groups on day 42 after the first vaccination. Similarly, higher levels of specific IgG2a were observed in experimental groups G2, G3, and G4 compared to the IgG1 levels on day 42. G4 showed a significant (p < .05) humoral response against both antigens of the antigenic formulations. The cellular immune response induced by immunization was characterized by a significant (p < .05) production of interferon-γ compared to that in the control, while the concentrations of interleukin (IL)-4 and IL-12 were not significant in any group. A significant increase of tumor necrosis factor was observed only in G4. The survival rates after the challenge were 30% (rPLD), 40% (rPLD + rCP09720), and 50% (rPLD + rCP01850). Thus, the association of rCP01850 with rPLD resulted in the best protection against the challenge with C. pseudotuberculosis and induced a more intense type 1 T-helper cell immune response.

Insight of Genus Corynebacterium: Ascertaining the Role of Pathogenic and Non-pathogenic Species

This review gathers recent information about genomic and transcriptomic studies in the Corynebacterium genus, exploring, for example, prediction of pathogenicity islands and stress response in different pathogenic and non-pathogenic species. In addition, is described several phylogeny studies to Corynebacterium, exploring since the identification of species until biological speciation in one species belonging to the genus Corynebacterium. Important concepts associated with virulence highlighting the role of Pld protein and Tox gene. The adhesion, characteristic of virulence factor, was described using the sortase mechanism that is associated to anchorage to the cell wall. In addition, survival inside the host cell and some diseases, were too addressed for pathogenic corynebacteria, while important biochemical pathways and biotechnological applications retain the focus of this review for non-pathogenic corynebacteria. Concluding, this review broadly explores characteristics in genus Corynebacterium showing to have strong relevance inside the medical, veterinary, and biotechnology field.

Recombinant esterase from Corynebacterium pseudotuberculosis in DNA and subunit recombinant vaccines partially protects mice against challenge

PURPOSE

We tested the efficacy of the esterase encoded by cp1002_RS09720 from Corynebacteriumpseudotuberculosis in recombinant subunit and DNA caseous lymphadenitis (CLA) vaccines. This target was predicted as one of the best CLA vaccine candidates by mature epitope density analysis.

METHODOLOGY

Gene cp1002_RS09720 was cloned into two different vectors (pAE for subunit vaccine and pTARGET for DNA vaccine). Four groups of 15 mice each were immunized with the recombinant esterase rCP09720 associated with aluminium hydroxide adjuvant (G1), pTARGET/cp09720 DNA vaccine (G2), a naked pTARGET (G3) or PBS as a negative control (G4). Immunization occurred in two doses intercalated by a 21 day interval. Twenty-one days after the last dose administration, animals were challenged with a virulent C. pseudotuberculosis MIC-6 strain.

RESULTS

G1 showed high levels of IgG1 and IgG2a on days 21 and 42 post-immunization and a significant level of IFN-γ (P<0.05), suggesting a Th1 response. The protection levels obtained were 58.3 and 16.6 % for G1 and G2, respectively.

CONCLUSION

The subunit vaccine composed of the recombinant esterase rCP09720 and Al(OH)3 is a promising antigenic formulation for use against CLA.