Dengue virus (DENV) has become a global health threat with about half of the world’s population at risk of infection. Although the disease caused by DENV is self-limiting in the first infection, the antibody-dependent enhancement (ADE) effect increases the mortality in the second infection with a heterotypic virus. Since there is no specific efficient medicine in treatment, it is urgent to develop vaccines to prevent infection and disease progression. Currently, only a live attenuated vaccine, chimeric yellow fever 17D—tetravalent dengue vaccine (CYD-TDV), has been licensed for clinical use in some countries, and many candidate vaccines are still under research and development. This review discusses the progress, strengths, and weaknesses of the five types of vaccines including live attenuated vaccine, inactivated virus vaccine, recombinant subunit vaccine, viral vectored vaccine, and DNA vaccine.

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Background The entomopathogenic fungus Beauveria bassiana has been widely used to kill mosquito larvae and adults in the laboratory and field. However, its slow action of killing has hampered its widespread application. In our study, the B . bassiana fungus was genetically modified to express the Bacillus thuringiensis (Bt) toxin Cyt2Ba to improve its efficacy in killing mosquitoes. Methodology/Principal findings The efficacy of the wild type (WT) of B . bassiana and a transgenic strain expressing Cyt2Ba toxin ( Bb -Cyt2Ba) was evaluated against larval and adult Aedes mosquitoes ( Aedes aegypti and Aedes albopictus ) using insect bioassays. The Bb -Cyt2Ba displayed increased virulence against larval and adult Aedes mosquitoes compared with the WT: for Ae . aegypti adults, the median lethal time (LT 50 ) was decreased by 33% at the concentration of 1× 10 8 conidia/ml, 19% at 1× 10 7 conidia/ml and 47% at 1× 10 6 conidia/ml. The LT 50 for Ae . albopictus adults was reduced by 20%, 23% and 29% at the same concentrations, respectively. The LT 50 for Ae . aegypti larvae was decreased by 42% at 1× 10 7 conidia/ml and 25% at 1× 10 6 conidia/ml, and that for Ae . albopictus larvae was reduced by 33% and 31% at the same concentrations, respectively. In addition, infection with Bb -Cyt2Ba resulted in a dramatic reduction in the fecundity of Aedes mosquitoes. Conclusions/Significance In conclusion, our study demonstrated that the virulence of B . bassiana against mosquitoes can be significantly improved by introducing the Bt toxin gene Cyt2Ba into the genome to express the exogenous toxin in the fungus. The transgenic strain Bb -Cyt2Ba significantly reduced the survival and fecundity of Ae . aegypti and Ae . albopictus compared with the WT strain, which suggested that this recombinant B . bassiana has great potential for use in mosquito control.

Terpene synthases (TPSs) are essential for forming terpenes, which play numerous functional roles in attracting pollinators, defending plants, and moderating the interaction between plants. TPSs have been reported in some orchids, but genome-wide identification of terpenes in Cymbidium faberi is still lacking. In this study, 32 putative TPS genes were classified in C. faberi and divided into three subfamilies (TPS-a, TPS-b, and TPS-e/f). Motif and gene structure analysis revealed that most CfTPS genes had the conserved aspartate-rich DDxxD motif. TPS genes in the TPS-a and TPS-b subfamilies had variations in the RRX8W motif. Most cis-elements of CfTPS genes were found in the phytohormone responsiveness category, and MYC contained most of the numbers associated with MeJA responsiveness. The Ka/Ks ratios of 12/13 CfTPS gene pairs were less than one, indicated that most CfTPS genes have undergone negative selection. The tissue-specific expression patterns showed that 28 genes were expressed in at least one tissue in C. faberi, and TPS genes were most highly expressed in flowers, followed by leaves and pseudobulbs. In addition, four CfTPS genes were selected for the real-time reverse transcription quantitative PCR (RT-qPCR) experiment. The results revealed that CfTPS12, CfTPS18, CfTPS23, and CfTPS28 were mainly expressed in the full flowering stage. CfTPS18 could convert GPP to β-myrcene, geraniol, and α-pinene in vitro. These findings of CfTPS genes of C. faberi may provide valuable information for further studies on TPSs in orchids.

Androctonus australis Hector insect toxin (AaIT), an insect-selective toxin, was identified in the venom of the scorpion Androctonus australis. The exclusive and specific target of the toxin is the voltage-gated sodium channels of the insect, resulting in fast excitatory paralysis and even death. Because of its strict toxic selectivity and high bioactivity, AaIT has been widely used in experiments exploring pest bio-control. Recombinant expression of AaIT in a baculovirus or a fungus can increase their virulence to insect pests and diseases vectors. Likewise, transgenic plants expressing AaIT have notable anti-insect activity. AaIT is an efficient toxin and has great potential to be used in the development of commercial insecticides.