In this task, you're given a paragraph from the research paper and your task is to generate a suitable title for the research paper based on the given paper. Under 100 words is a good title length.

Quinone-methide triterpenes, celastrol (1), pristimerin (2), tingenone (3), and iguesterin (4) were isolated from Triterygium regelii and dihydrocelastrol (5) was synthesized by hydrogenation under palladium catalyst. Isolated quinone-methide triterpenes (1-4) and 5 were evaluated for SARS-CoV 3CL pro inhibitory activities and showed potent inhibitory activities with IC 50 values of 10.3, 5.5, 9.9, and 2.6 lM, respectively, whereas the corresponding 5 having phenol moiety was observed in low activity (IC 50 = 21.7 lM). As a result, quinone-methide moiety in A-ring and more hydrophobic E-ring assist to exhibit potent activity. Also, all quinone-methide triterpenes 1-4 have proven to be competitive by the kinetic analysis.
SARS-CoV 3CL pro inhibitory effects of quinone-methide triterpenes from Tripterygium regelii

With sharp increasing in biological sequences, the traditional sequence alignment methods become unsuitable and infeasible. It motivates a surge of fast alignment-free techniques for sequence analysis. Among these methods, many sorts of feature vector methods are established and applied to reconstruction of species phylogeny. The vectors basically consist of some typical numerical features for certain biological problems. The features may come from the primary sequences, secondary or three dimensional structures of macromolecules. In this study, we propose a novel numerical vector based on only primary sequences of organism to build their phylogeny. Three chemical and physical properties of primary sequences: purine, pyrimidine and keto are also incorporated to the vector. Using each property, we convert the nucleotide sequence into a new sequence consisting of only two kinds of letters. Therefore, three sequences are constructed according to the three properties. For each letter of each sequence we calculate the number of the letter, the average position of the letter and the variation of the position of the letter appearing in the sequence. Tested on several datasets related to mammals, viruses and bacteria, this new tool is fast in speed and accurate for inferring the phylogeny of organisms. Published: xx xx xxxx OPEN www.nature.com/scientificreports/ 2 Scientific RepoRts | 7: 12226 |
A novel fast vector method for genetic sequence comparison OPEN

The nucleoprotein (NP) of Newcastle disease virus (NDV) functions primarily to encapsidate the virus genome for the purpose of RNA transcription, replication, and packaging. This conserved multifunctional protein is also efficient in inducing NDV-specific antibody in chickens. Here, we localized a conserved B-cell immunodominant epitope (IDE) spanning residues 447 to 455 and successfully generated a recombinant NDV lacking the IDE by reverse genetics. Despite deletion of NP residues 443 to 460 encompassing the NP-IDE, the mutant NDV propagated in embryonated specific-pathogen-free chicken eggs to a level comparable to that of the parent virus. In addition, a B-cell epitope of the S2 glycoprotein of murine hepatitis virus (MHV) was inserted in-frame to replace the NP-IDE. Recombinant viruses properly expressing the introduced MHV epitope were successfully generated, demonstrating that the NP-IDE not only is dispensable for virus replication but also can be replaced by foreign sequences. Chickens immunized with the hybrid recombinants produced specific antibodies against the S2 glycoprotein of MHV and completely lacked antibodies directed against the NP-IDE. These marked-NDV recombinants, in conjunction with a diagnostic test, enable serological differentiation of vaccinated animals from infected animals and may be useful tools in ND eradication programs. The identification of a mutation-permissive region on the NP gene allows a rational approach to the insertion of protective epitopes and may be relevant for the design of NDV-based cross-protective marker vaccines.

Newcastle Disease Virus (NDV) Marker Vaccine: an Immunodominant Epitope on the Nucleoprotein Gene of NDV Can Be Deleted or Replaced by a Foreign Epitope