Optical technologies can be developed as practical tools for monitoring plant health by providing unique spectral signatures that can be related to specific plant stresses. Signatures from thermal and fluorescence imaging have been used successfully to track pathogen invasion before visual symptoms are observed. Another approach for non-invasive plant health monitoring involves elucidating the manner with which light interacts with the plant leaf and being able to identify changes in spectral characteristics in response to specific stresses. To achieve this, an important step is to understand the biochemical and anatomical features governing leaf reflectance, transmission and absorption. Many studies have opened up possibilities that subtle changes in leaf reflectance spectra can be analyzed in a plethora of ways for discriminating nutrient and water stress, but with limited success. There has also been interest in developing transgenic phytosensors to elucidate plant status in relation to environmental conditions. This approach involves unambiguous signal creation whereby genetic modification to generate reporter plants has resulted in distinct optical signals emitted in response to specific stressors. Most of these studies are limited to laboratory or controlled greenhouse environments at leaf level. The practical translation of spectral cues for application under field conditions at canopy and regional levels by remote aerial sensing remains a challenge. The movement towards technology development is well exemplified by the Controlled Ecological Life Support System under development by NASA which brings together technologies for monitoring plant status concomitantly with instrumentation for environmental monitoring and feedback control.

The NS2B cofactor is critical for proteolytic activation of the flavivirus NS3 protease. To elucidate the mechanism involved in NS2B-mediated activation of NS3 protease, molecular dynamic simulation, principal component analysis, molecular docking, mutagenesis, and bioassay studies were carried out on both the dengue virus NS3pro and NS2B-NS3pro systems. The results revealed that the NS2B-NS3pro complex is more rigid than NS3pro alone due to its robust hydrogen bond and hydrophobic interaction networks within the complex. These potent networks lead to remodeling of the secondary and tertiary structures of the protease that facilitates cleavage sequence recognition and binding of substrates. The cofactor is also essential for proper domain motion that contributes to substrate binding. Hence, the NS2B cofactor plays a dual role in enzyme activation by facilitating the refolding of the NS3pro domain as well as being directly involved in substrate binding/interactions. Kinetic analyses indicated for the first time that Glu92 and Asp50 in NS2B and Gln27, Gln35, and Arg54 in NS3pro may provide secondary interaction points for substrate binding. These new insights on the mechanistic contributions of the NS2B cofactor to NS3 activation may be utilized to refine current computer-based search strategies to raise the quality of candidate molecules identified as potent inhibitors against flaviviruses.The spectrum of clinical manifestations caused by the dengue virus, namely, dengue fever, dengue hemorrhagic fever, and dengue shock syndrome, are increasing in severity and present major threats to global health. In the tropics and subtropical regions, the fatality rate ranges between 1 and 10% of more than 1 million cases of dengue hemorrhagic fever every year. With exacerbation of disease infection rates aided by global warming, growing urbanization, and rapid expansion of international trade and travel, the virus is now endemic in more than 100 countries and threatens more than a quarter of the world's population. Currently, there is no vaccine or effective therapeutic agent available to protect against or cure acute dengue viral infections.Dengue viruses are members of the Flaviviridae family. They are small, enveloped positive-sense RNA viruses transmitted by Aedes aegypti and Aedes albopictus mosquitoes (6). Dengue virus type 2 (DEN2), the most prevalent of the four serotypes, contains a single-stranded RNA and encodes a large single polyprotein precursor of 3,391 amino acid residues which consists of three structural proteins (C, prM, and E) and seven nonstructural proteins (NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5) (16). Processing of the polyprotein precursor to release mature viral proteins is mediated co-and posttranslationally by host proteases and the virus-encoded two-component protease NS2B-NS3pro (8). Thus, the essential role of NS2B-NS3pro for viral replication makes it an attractive target for the development of effective antiviral drug inhibitors with therapeutic applications against dengue hemorrhagic feve...

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