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Dengue viruses are emerging mosquito-borne pathogens belonging to Flaviviridae family which are transmitted to humans via the bites of infected mosquitoes Aedes aegypti and Aedes albopictus. Because of the wide distribution of these mosquito vectors, more than 2.5 billion people are approximately at risk of dengue infection. Dengue viruses cause dengue fever and severe life-threatening illnesses as well as dengue hemorrhagic fever and dengue shock syndrome. All four serotypes of dengue virus can cause dengue diseases, but the manifestations are nearly different depending on type of the virus in consequent infections. Infection by any serotype creates life-long immunity against the corresponding serotype and temporary immunity to the others. This transient immunity declines after a while (6 months to 2 years) and is not protective against other serotypes, even may enhance the severity of a secondary heterotypic infection with a different serotype through a phenomenon known as antibody-depended enhancement (ADE). Although, it can be one of the possible explanations for more severe dengue diseases in individuals infected with a different serotype after primary infection. The envelope protein (E protein) of dengue virus is responsible for a wide range of biological activities, including binding to host cell receptors and fusion to and entry into host cells. The E protein, and especially its domain III (EDIII), stimulates host immunity responses by inducing protective and neutralizing antibodies. Therefore, the dengue E protein is an important antigen for vaccine development and diagnostic purposes. Here, we have provided a comprehensive review of dengue disease, vaccine design challenges, and various approaches in dengue vaccine development with emphasizing on newly developed envelope domain III-based dengue vaccine candidates.

Cysteine/histidine-dependent amidohydrolase/peptidase (CHAP) and amidase are known as catalytic domains of the bacteriophage-derived endolysin LysK and were previously reported to show lytic activity against methicillin-resistant Staphylococcus aureus (MRSA). In the current study, the in silico design and analysis of chimeric CHAP-amidase model was applied to enhance the stability and solubility of protein, which was achieved through improving the properties of primary, secondary and tertiary structures. The coding gene sequence of the chimeric CHAP-amidase was synthesized and subcloned into the pET-22(+) expression vector, and the recombinant protein was expressed in E. coli BL21 (DE3) strain. Subsequent affinity-based purification yielded ~12 mg soluble protein per liter of E. coli culture. Statistical analysis indicated that concentrations of ≥1 μg/mL of the purified protein have significant antibacterial activity against S. aureus MRSA252 cells. The engineered chimeric CHAP-amidase exhibited 3.2 log reduction of MRSA252 cell counts at the concentration of 10 μg/mL. A synergistic interaction between CHAP-amidase and vancomycin was detected by using checkerboard assay and calculating the fractional inhibitory concentration (FIC) index. This synergistic effect was shown by 8-fold reduction in the minimum inhibitory concentration of vancomycin. The chimeric CHAP-amidase displayed strong antibacterial activity against S. aureus, S. epidermidis, and enterococcus. However, it did not indicate any significant antibacterial activity against E. coli and Lactococcus lactis. Taken together, these findings suggest that our chimeric CHAP-amidase might represent potential to be used for the development of efficient antibacterial therapies targeting MRSA and certain Gram-positive bacteria.

The cyanobacteria and predominantly the genus Nostoc are known as producers of dozens pharmacologically active compounds, composed of abnormal amino acids, which have aided them to survive in varied and highly competitive ecological niches. Their function as antiviral, antitumour, antibacterial, anti‐HIV and a food additive has been well set up. This high degree of chemical diversity in bioactive compounds of cyanobacterial Nostoc species may thus create a prolific source of new entities leading to the development of new pharmaceuticals. This review provides the comprehensive overview of metabolites and novel bioactive natural products produced by cyanobacteria of the genus Nostoc, which present biological activity and can be used for the treatment of various human and animal disorders.

Bacterial mannitol 1-phosphate dehydrogenase (mtlD) gene was introduced into potato (Solanum tuberosum L.) by Agrobacterium tumefaciens-mediated transformation. Transgenic plants were selected on a medium containing 100 mg l -1 kanamycin and confirmed by polymerase chain reaction (PCR), Southern blotting, and RT-PCR analyses. All of the selected transformants accumulated mannitol, a sugar alcohol that is not found in wildtype potato. Experiments designed for testing salt tolerance revealed that there was enhanced NaCl tolerance of the transgenic lines both in vitro and in hydroponic culture. Compared to 0 mM NaCl, the shoot fresh weight of wildtype plants was reduced by 76.5% at 100 mM NaCl under hydroponic conditions. However, under the same condition, the shoot fresh weight of transgenic plants was reduced only by 17.3%, compared to 0 mM NaCl treatment. The improved tolerance of this transgenic line may be attributed to the induction and progressive accumulation of mannitol in the roots and shoots of the plants. In contrast to in vitro experiments, the mannitol content in the transgenic roots and shoots increased at 50 mM NaCl and decreased slightly at 75 and 100 mM NaCl, respectively. Overall, the amount of accumulated mannitol in the transgenic lines was too small to act as an osmolyte; thus, it might act as an osmoprotectant. However, the results demonstrated that mannitol had more contribution to osmotic adjustment in the roots (but not in shoots). Finally, we concluded that mtlD expression in transgenic potato plants can significantly increase the mannitol accumulation that contributes to the enhanced tolerance to NaCl stress. Furthermore, although this enhanced tolerance resulted mainly from an osmoprotectant action, an osmoregulatory effect could not be ruled out.