Evaluation of the Association of Recombinant Proteins NanH and PknG from Corynebacterium pseudotuberculosis Using Different Adjuvants as a Recombinant Vaccine in Mice.

Caseous lymphadenitis is a chronic contagious disease that causes economic losses worldwide. Treatments are ineffective, thus demonstrating the importance of vaccination. In this study, rNanH and rPknG proteins from Corynebacterium pseudotuberculosis were associated with saponin or aluminum hydroxide adjuvants. Three experimental groups (10 animals each) were immunized with sterile 0.9% saline solution (G1), rNanH + rPknG + Saponin (G2), rNanH + rPknG + Al(OH)3 (G3). The mice received two vaccine doses 21 days apart. Animals were challenged 21 days after the last immunization and evaluated for 50 days, with endpoint criteria applied when needed. The total IgG production levels of the experimental groups increased significantly on day 42 when compared to the control (p < 0.05). When tested against rNanH, G2 had a better rate of anti-rNanH antibodies compared to G3. In the anti-rPknG ELISA, the levels of total IgG, IgG1, and IgG2a antibodies were higher in G2. The vaccines generated partial protection, with 40% of the animals surviving the challenge. The association of recombinant NanH and PknG proteins led to promising protection rates in mice, and although using different adjuvants did not interfere with the survival rate, it influenced the immune response generated by the vaccine formulations.

In vitro and in silico trichomonacidal activity of 2,8-bis(trifluoromethyl) quinoline analogs against Trichomonas vaginalis.

Trichomoniasis is a great public health burden worldwide and the increase in treatment failures has led to a need for finding alternative molecules to treat this disease. In this study, we present in vitro and in silico analyses of two 2,8-bis(trifluoromethyl) quinolines (QDA-1 and QDA-2) against Trichomonas vaginalis. For in vitro trichomonacidal activity, up to seven different concentrations of these drugs were tested. Molecular docking, biochemical, and cytotoxicity analyses were performed to evaluate the selectivity profile. QDA-1 displayed a significant effect, completely reducing trophozoites viability at 160 µM, with an IC50 of 113.8 µM, while QDA-2 at the highest concentration reduced viability by 76.9%. QDA-1 completely inhibited T. vaginalis growth and increased reactive oxygen species production and lipid peroxidation after 24 h of treatment, but nitric oxide accumulation was not observed. In addition, molecular docking studies showed that QDA-1 has a favorable binding mode in the active site of the T. vaginalis enzymes purine nucleoside phosphorylase, lactate dehydrogenase, triosephosphate isomerase, and thioredoxin reductase. Moreover, QDA-1 presented a level of cytotoxicity by reducing 36.7% of Vero cells' viability at 200 µM with a CC50 of 247.4 µM and a modest selectivity index. In summary, the results revealed that QDA-1 had a significant anti-T. vaginalis activity. Although QDA-1 had detectable cytotoxicity, the concentration needed to eliminate T. vaginalis trophozoites is lower than the CC50 encouraging further studies of this compound as a trichomonacidal agent.

In silico analyses and design of a chimeric protein containing epitopes of SpaC, PknG, NanH, and SodC proteins for the control of caseous lymphadenitis.

Caseous lymphadenitis (CLA) is an infectious disease that affects goats and sheep causing drastic impacts on milk and meat production and is caused by Corynebacterium pseudotuberculosis. The disease can be prevented through vaccination but currently, vaccines demonstrate limited efficacy consequently leading to a need for the development of new ones. Here, we described the in silico development of a new chimeric protein constructed with epitopes identified from the sequences of the genes nanH, pknG, spaC, and sodC, previously described as potential vaccinal targets against C. pseudotuberculosis. The chimera was expressed, purified, and its immunogenicity was evaluated using sera of immunized mice. Results indicate the chimeric protein was able to stimulate antibody production. Additionally, analysis using serum from naturally infected goats showed that the protein is recognized by sera from these animals, indicating the possibility for using this chimera in new diagnostic methods. KEY POINTS: • The chimera was expressed with 52 kDa and a yield of 7 mg/L after purification. • The chimera was recognized by the sera of animals immunized with this formulation. • Chimera reacted with the serum of goats naturally infected with C. pseudotuberculosis.

Cell viability analysis of Toxocara cati larvae with LIVE / DEAD® Viability/Cytotoxicity kit.

Toxocara spp. are responsible for causing toxocariasis, a zoonotic disease of global significance. In some countries of South America, toxocariasis is considered the most prevalent human helminthic infection. The objective of this study was to evaluate LIVE/DEAD® Viability/Cytotoxicity kit as an alternative method to analyze the viability of Toxacara cati larvae. Two control groups were used to confirm the usage of this methodology: 100 untreated T. cati larvae as a negative control (G1) and 100 T. cati larvae killed by thermal shock as a positive control (G2). Subsequently, the viability of T. cati larvae was assessed by the exclusion of the trypan blue dye and by LIVE/DEAD® Viability/Cytotoxicity kit, as well as observation of motility and morphology. In order to confirm the larvicidal effect, T. cati larvae G1 and G2 were inoculated in mice to evaluate their progression in vivo. As expected, G1 showed negative staining by Trypan blue and was stained green by LIVE/DEAD® Viability/Cytotoxicity kit in all the exposure periods. Moreover, G1 presented 100% of relative motility (RM) (score of 5). G2 group was stained blue by Trypan blue and red by LIVE/DEAD® Viability/Cytotoxicity kit, and had 0% RM (score zero) in 24 h of incubation period. In mice, G2 was not viable and, therefore, was not able to infect the animals. In mice inoculated with G1, however, larvae were recovered from all the evaluated organs, except eyes. These results demonstrate that the viability of T. cati larvae was accurately obtained by the LIVE/DEAD® Viability/Cytotoxicity kit, making it an alternative method for viability evaluation.

Antiparasitic activity of furanyl N-acylhydrazone derivatives against Trichomonas vaginalis: in vitro and in silico analyses.

BACKGROUND: Trichomonas vaginalis is the causative agent of trichomoniasis, which is one of the most common sexually transmitted diseases worldwide. Trichomoniasis has a high incidence and prevalence and is associated with serious complications such as HIV transmission and acquisition, pelvic inflammatory disease and preterm birth. Although trichomoniasis is treated with oral metronidazole (MTZ), the number of strains resistant to this drug is increasing (2.5-9.6%), leading to treatment failure. Therefore, there is an urgent need to find alternative drugs to combat this disease. METHODS: Herein, we report the in vitro and in silico analysis of 12 furanyl N-acylhydrazone derivatives (PFUR 4, a-k) against Trichomonas vaginalis. Trichomonas vaginalis ATCC 30236 isolate was treated with seven concentrations of these compounds to determine the minimum inhibitory concentration (MIC) and 50% inhibitory concentration (IC50). In addition, compounds that displayed anti-T. vaginalis activity were analyzed using thiobarbituric acid reactive substances (TBARS) assay and molecular docking. Cytotoxicity analysis was also performed in CHO-K1 cells. RESULTS: The compounds PFUR 4a and 4b, at 6.25 µM, induced complete parasite death after 24 h of exposure with IC50 of 1.69 µM and 1.98 µM, respectively. The results showed that lipid peroxidation is not involved in parasite death. Molecular docking studies predicted strong interactions of PFUR 4a and 4b with T. vaginalis enzymes, purine nucleoside phosphorylase, and lactate dehydrogenase, while only PFUR 4b interacted in silico with thioredoxin reductase and methionine gamma-lyase. PFUR 4a and 4b led to a growth inhibition (< 20%) in CHO-K1 cells that was comparable to the drug of choice, with a promising selectivity index (> 7.4). CONCLUSIONS: Our results showed that PFUR 4a and 4b are promising molecules that can be used for the development of new trichomonacidal agents for T. vaginalis.

2'-Hydroxychalcones as an alternative treatment for trichomoniasis in association with metronidazole.

The treatment for trichomoniasis, based on 5'-nitroimidazol agents, has been presenting failures related to allergic reactions, side effects, and the emergence of resistant isolates. There are no alternative drugs approved for the treatment of these cases; thus, the search for new active molecules is necessary. In this scenario, chalcones have been extensively studied for their promising biological activities. Here, we presented the synthesis of three hydroxychalcones (3a, b, and c), in vitro and in silico analyses against Trichomonas vaginalis. The in vitro biological evaluation showed that hydroxychalcone 3c presented anti-T. vaginalis activity, with complete death in 12 h of incubation at minimum inhibitory concentration (MIC) of 100 µM. 3c showed a dose-dependent cytotoxicity against mammalian VERO cell line, but the association of 3c at 12.5 µM and metronidazole (MTZ) at 40 µM showed 95.31% activity against T. vaginalis trophozoites after 24 h of exposure and did not affect the VERO cell growth, appearing to be a good alternative. In silico analysis by molecular docking showed that 3c could inhibit the activity of TvMGL (methionine gamma-lyase), TvLDH (lactate dehydrogenase), and TvPNP (purine nucleoside phosphorylase) affecting the T. vaginalis survival and also suggesting a different mechanism of action from MTZ. Therefore, these results propose that hydroxychalcones are promising anti-T. vaginalis agents and must be considered for further investigations regarding trichomoniasis treatment.