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Clostridium perfringens is an anaerobic bacterium that produces several toxins. Of these, the alpha, beta, and epsilon toxins are responsible for causing the most severe C. perfringens-related diseases in farm animals. The best way to control these diseases is through vaccination. However, commercially available vaccines are based on inactivated toxins and have many production drawbacks, which can be overcome through the use of recombinant antigens. In this study, we produced recombinant alpha, beta, and epsilon toxins in Escherichia coli to formulate a trivalent vaccine. Its effectiveness was evaluated through a potency test in rabbits, in which the vaccine generated 9.6, 24.4, and 25.0 IU/mL of neutralizing antibodies against the respective toxins. Following this, cattle, sheep, and goats received the same formulation, generating, respectively, 5.19 ± 0.48, 4.34 ± 0.43, and 4.70 ± 0.58 IU/mL against alpha toxin, 13.71 ± 1.17 IU/mL (for all three species) against beta toxin, and 12.74 ± 1.70, 7.66 ± 1.69, and 8.91 ± 2.14 IU/mL against epsilon toxin. These levels were above the minimum recommended by international protocols. As such, our vaccine was effective in generating protective antibodies and, thus, may represent an interesting alternative for the prevention of C. perfringens-related intoxications in farm animals.

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Electrochemical sensors and biosensors are useful techniques for fast, inexpensive, sensitive, and easy detection of innumerous specimen. In face of COVID-19 pandemic, it became evident the necessity of a rapid and accurate diagnostic test, so the impedimetric immunosensor approach can be a good alternative to replace the conventional tests due to the specific antibody-antigen binding interaction and the fast response in comparison to traditional methods. In this work, a modified electrode with electrosynthesized PEDOT and gold nanoparticles followed by the immobilization of truncated nucleoprotein (N aa160-406aa) was used for a fast and reliable detection of antibodies against COVID-19 in human serum sample. The method consists in analyzing the charge-transfer resistance (R CT ) variation before and after the modified electrode comes into contact with the positive and negative serum sample for COVID-19, using [Fe(CN) 6 ] 3-/4− as a probe. The results show a linear and selective response for serum samples diluted in a range of 2.5 × 10 3 to 20 × 10 3 . Also, the electrode material was fully characterized by Raman spectroscopy, transmission electron microscopy and scanning electron microscopy coupled with EDS, indicating that the gold nanoparticles were well distributed around the polymer matrix and the presence of the biological sample was confirmed by EDS analysis. EIS measurements allowed to differentiate the negative and positive samples by the difference in the R CT magnitude, proving that the material developed here has potential properties to be applied in impedimetric immunosensors for the detection of SARS-CoV-2 antibodies in about 30 minutes.

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Leptospirosis is a zoonotic disease that occurs worldwide and is caused by pathogenic bacteria of the genus Leptospira. Clinical manifestations of leptospirosis are similar to other febrile illnesses and this fact frequently retards the beginning of antibiotic therapy. Thus, early and accurate diagnosis is a prerequisite for proper treatment of leptospirosis. Antigen and DNA-based detection tests offer potential advantage over tests based on antibody detection for early diagnosis of leptospirosis since antibodies only reach detectable levels several days after the onset of the infection. This work describes a method for detection of pathogenic Leptospira that associates an immunoseparation step with a PCR assay and uses an internal amplification control (IAC) to ensure accuracy of the test. The immunoseparation was performed with protein A-magnetic beads in house coated with an MAb specific for LipL32, the major outer membrane protein of pathogenic Leptospira; PCR was performed using lipL32 specific primers. The IMS-PCR method enhanced detection of Leptospira in experimentally contaminated human sera and urine when compared to PCR performed alone. IMS-PCR was able to detect 10(2) Leptospira cells per mL of human sera and urine, corresponding to 25 genomic copies per PCR reaction.