Toxoplasma gondii is one of the most widespread obligatory parasitic protozoa and infects nearly all warm-blooded animals, leading to toxoplasmosis. The therapeutic drugs currently administered, like the combination of pyrimethamine and sulfadiazine, show high rates of toxic side effects, and drug resistance is encountered in some cases. Resveratrol is a natural plant extract with multiple functions, such as antibacterial, anticancer, and antiparasite activities. In this study, we evaluated the inhibitory effects of resveratrol on tachyzoites of the Toxoplasma gondii RH strain extracellularly and intracellularly. We demonstrate that resveratrol possesses direct antitoxoplasma activity by reducing the population of extracellularly grown tachyzoites, probably by disturbing the redox homeostasis of the parasites. Moreover, resveratrol was also able to release the burden of cellular stress, promote apoptosis, and maintain the autophagic status of macrophages, which turned out to be regulated by intracellular parasites, thereby functioning indirectly in eliminating T. gondii. In conclusion, resveratrol has both direct and indirect antitoxoplasma effects against RH tachyzoites and may possess the potential to be further evaluated and employed for toxoplasmosis treatment.

The global outbreak of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) urgently requires an effective vaccine for prevention. In this study, 66 epitopes containing pentapeptides of SARS‐CoV‐2 spike protein in the IEDB database were compared with the amino acid sequence of SARS‐CoV‐2 spike protein, and 66 potentially immune‐related peptides of SARS‐CoV‐2 spike protein were obtained. Based on the single‐nucleotide polymorphisms analysis of spike protein of 1218 SARS‐CoV‐2 isolates, 52 easily mutated sites were identified and used for vaccine epitope screening. The best vaccine candidate epitopes in the 66 peptides of SARS‐CoV‐2 spike protein were screened out through mutation and immunoinformatics analysis. The best candidate epitopes were connected by different linkers in silico to obtain vaccine candidate sequences. The results showed that 16 epitopes were relatively conservative, immunological, nontoxic, and nonallergenic, could induce the secretion of cytokines, and were more likely to be exposed on the surface of the spike protein. They were both B‐ and T‐cell epitopes, and could recognize a certain number of HLA molecules and had high coverage rates in different populations. Moreover, epitopes 897‐913 were predicted to have possible cross‐immunoprotection for SARS‐CoV and SARS‐CoV‐2. The results of vaccine candidate sequences screening suggested that sequences (without linker, with linker GGGSGGG, EAAAK, GPGPG, and KK, respectively) were the best. The proteins translated by these sequences were relatively stable, with a high antigenic index and good biological activity. Our study provided vaccine candidate epitopes and sequences for the research of the SARS‐CoV‐2 vaccine.

The present work aimed to evaluate 16S rRNA, khe and rpoB gene sequencing for the identification of Klebsiella pneumoniae in comparison with phenotypic methods. Fifteen clinical isolates were examined, which were initially identified as K. pneumoniae subsp. pneumoniae using the automated VITEK 32 system in two hospitals in Enshi City, China. Their identity was further supported by conventional phenotypic methods on the basis of morphological and biochemical characteristics. Using Bayesian phylogenetic analyses and haplotypes network reconstruction, 13 isolates were identified as K.pneumoniae, whereas the other two isolates (K19, K24) were classified as Shigella sp. and Enterobacter sp., respectively. Of the three genes, 16S rRNA and khe gene could discriminate the clinical isolates at the genus level, whereas rpoB could discriminate Klebsiella at the species and even subspecies level. Overall, the gene tree based on rpoB is more compatible with the currently accepted classification of Klebsiella than those based on 16S rRNA and khe genes, showing that rpoB can be a powerful tool for identification of K. pneumoniae isolates. Above all, our study challenges the utility of khe as a species-specific marker for identification of K. pneumoniae.Electronic supplementary material The online version of this article

Visceral leishmaniasis (VL) is the most fatal form of leishmaniasis if left untreated and 50,000 to 90,000 new cases of VL occur worldwide each year. Although various vaccines had been studied in animal models, none of them was eligible to prevent human from infections. In this study, according to the silico analysis of Leishmania Amastin, Kmp-11 and Gp63 protein, dominant epitope sequences of these proteins were selected and linked to construct dominant multi-epitopes DNA and protein vaccines (Amastin-Kmp-11, Amastin-Gp63 and Kmp-11-Gp63) against VL. BALB/c mice were immunized with a DNA prime-protein boost immunization strategy and challenged with a new Leishmania parasite strain isolated from a VL patient. After immunization, the results including specific antibody titers, IL-4 and TNF-α levels, and CD4 and CD8 T cell proportion suggested the potent immunogenicity of the three vaccines. After infection, the results of spleen parasite burdens in the three vaccine groups were significantly lower than those of control groups, and the parasite reduction rates of Amastin-Kmp-11, Amastin-Gp63 and Kmp-11-Gp63 groups were 89.38%, 91.01% and 88.42%, respectively. Spleen smear observation and liver histopathological changes showed that all vaccine groups could produce significant immunoprotection against VL and Amastin-Gp63 vaccine was the best. In conclusion, our work demonstrated that the three dominant multi-epitopes Amastin-Kmp-11, Amastin-Gp63 and Kmp-11-Gp63 DNA primeprotein boost vaccines might be new vaccine candidates for VL, and the Amastin-Gp63 vaccine have best efficacy.

Background Leishmaniasis caused by protozoan parasite Leishmania is a neglected disease which is endemic in the northwest of China. Reptiles were considered to be the potential reservoir hosts for mammalian Leishmaniasis, and Leishmania had been detected in lizards from the epidemic area in the northwest of China. To date, few studies are focused on the natural infection of snakes with Leishmania . Methods In this study, 15 snakes captured from 10 endemic foci in the northwest of China were detected Leishmania spp. on the base of mitochondrial cytochrome b , heat shock protein 70 gene and ribosomal internal transcribed spacer 1 regions, and identified with phylogenetic and network analyses. Result In total, Leishmania gene was found in 7 snakes. The phylogenetic inference trees and network analysis suggests that the species identification was confirmed as Leishmania donovani , L . turanica and L . ( Sauroleishmania ) sp. Conclusion Our work is the first time to investigate the natural Leishmania spp. infection of snakes in the northwest of China. Mammalian Leishmania ( L . donovani and L . turanica ) was discovered in snakes and the reptilian Leishmania ( Sauroleishmania sp.) was closely related to the clinical strains both prompt the importance of snakes in the disease cycle. To indicate the epidemiological involvement of snakes, a wide sample size in epidemic area and the pathogenic features of reptilian Leishmania promastigotes are recommended in the future research.