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

Assessment of rSodC, rPknG, rNanH, and rSpaC as Antigens for Diagnostic Tools Against Caseous Lymphadenitis

Corynebacterium pseudotuberculosis is a bacillus that causes caseous lymphadenitis in small ruminants, leading to great losses to rural producers; thus, an efficient diagnosis is necessary for using disease control measures. This study aimed to evaluate the antigenic potential of four C. pseudotuberculosis recombinant proteins (rSodC, rPknG, rNanH, and rSpaC) against sera of goat and sheep experimentally infected with one of three different C. pseudotuberculosis strains. Goats were infected with CAP76 or CAP21 strain (n = 10), sheep with VD57 strain (n = 6), and a group of not-infected animals (goats and sheep) were kept as a healthy control (healthy n = 12). Sera were collected at 0, 14, 60, 90, 180, or 190 days after inoculation for antigenicity testing using Western blotting and enzyme-linked immunosorbent assay (ELISA) techniques. Cross-reactivity tests with recombinant proteins were performed in goat serum experimentally vaccinated with Nocardia sp. or Rhodococcus equi bacterin. The rSodC protein showed discriminatory antigenic reactivity with a statistically significant difference against three different C. pseudotuberculosis strains evaluated in goats and sheep samples, while rPknG showed statistical significance only against two C. pseudotuberculosis strains evaluated in goats. rSodC was proved to be a strong candidate as a tool for diagnosis of C. pseudotuberculosis infection, once it was able to recognize antibodies against all strains evaluated in goats and sheep.

A journey through the Corynebacterium pseudotuberculosis proteome promotes insights into its functional genome

Background

Corynebacterium pseudotuberculosis is a Gram-positive facultative intracellular pathogen and the etiologic agent of illnesses like caseous lymphadenitis in small ruminants, mastitis in dairy cattle, ulcerative lymphangitis in equines, and oedematous skin disease in buffalos. With the growing advance in high-throughput technologies, genomic studies have been carried out to explore the molecular basis of its virulence and pathogenicity. However, data large-scale functional genomics studies are necessary to complement genomics data and better understating the molecular basis of a given organism. Here we summarize, MS-based proteomics techniques and bioinformatics tools incorporated in genomic functional studies of C. pseudotuberculosis to discover the different patterns of protein modulation under distinct environmental conditions, and antigenic and drugs targets.

Methodology

In this study we performed an extensive search in Web of Science of original and relevant articles related to methods, strategy, technology, approaches, and bioinformatics tools focused on the functional study of the genome of C. pseudotuberculosis at the protein level.

Results

Here, we highlight the use of proteomics for understating several aspects of the physiology and pathogenesis of C. pseudotuberculosis at the protein level. The implementation and use of protocols, strategies, and proteomics approach to characterize the different subcellular fractions of the proteome of this pathogen. In addition, we have discussed the immunoproteomics, immunoinformatics and genetic tools employed to identify targets for immunoassays, drugs, and vaccines against C. pseudotuberculosis infection.

Conclusion

In this review, we showed that the combination of proteomics and bioinformatics studies is a suitable strategy to elucidate the functional aspects of the C. pseudotuberculosis genome. Together, all information generated from these proteomics studies allowed expanding our knowledge about factors related to the pathophysiology of this pathogen.

rSodC is a potential antigen to diagnose Corynebacterium pseudotuberculosis by enzyme-linked immunoassay

Caseous lymphadenitis (CL) is a chronic infectious disease that affects sheep and goats. Many serological tests have been developed to detect the disease; one of the most widely used is the enzyme-linked immunosorbent assay (ELISA), due to its advantages, which include acceptable cost-effectiveness, applicability, sensitivity and specificity. ELISA formulations using recombinant proteins can exhibit significant sensitivity and specificity when using a single purified antigen. DTxR, Trx, TrxR, LexA, SodC, SpaC, NanH, and PknG recombinant proteins can be considered target proteins for ELISA development due to its extracellular or on the cell surface location, which allows a better recognition by the immune system. Therefore, the objectives of this study were to evaluate the antigenic reactivity of Corynebacterium pseudotuberculosis recombinant proteins in goat and sheep serum. Of eight proteins evaluated, rSodC was selected for validation assays with small ruminant serum samples from the semiarid region of the state of Bahia, Brazil. Validation assays with goat serum samples showed that ELISA-rSodC presented sensitivity and specificity of 96% and 94%, respectively. Validation assays with sheep serum showed that ELISA-rSodC exhibited sensitivity and specificity of 95% and 98%, respectively. Analysis of 756 field serum samples showed that rSodC identified 95 positive samples (23%) in goats and 75 positive samples (21%) in sheep. The ELISA with recombinant SodC protein developed in this study discriminated positive and negative serum samples with high levels of sensitivity and specificity. This formulation is promising for epidemiological surveys and CL control programs.

Trial registration AEC No 4958051018. 12/18/2018, retrospectively registered