ABSTRACT
Resumen El virus de la influenza A es el responsable de la gripe aviar, condición patológica que afecta principalmente aves, caballos y mamíferos marinos, sin embargo, el subtipo H5NI tiene la capacidad de infectar a los humanos de forma rápida, exponiéndolos a un posible evento pandémico. Por tanto, el objetivo de este estudio fue realizar el acoplamiento molecular y modelado tridimensional por homología de flavonoides derivados de amentoflavona con las neuraminidasas H1N1 y H5N1 del virus de gripe aviar. Inicialmente, se obtuvo por homología la estructura 3D de la neuraminidasa H1N1. Seguido, se realizó un acoplamiento molecular de H1N1 con seis ligandos (F36, Ginkgetin, 3S,3R, 5S,5R, 6S y 6R), y más adelante H5N1 y los ligandos F36, Ginkgetin, 5R y 6R. Finalmente, a los complejos obtenidos se les realizó un análisis de interacciones. Los resultados dejaron en evidencia una relación entre la actividad inhibitoria y las interacciones tipo puente de hidrógeno e hidrofóbicas formadas entre el sitio activo de las neuraminidasas y los ligandos. Además, se observó una mejora en la actividad inhibitoria de los ligandos para la estereoquímica tipo R y sustituyentes poco voluminosos. De ahí que se propongan la evaluación experimental de los ligandos 5R y 6R como potenciales inhibidores de H5N1.
Abstract The influenza A virus is responsible for bird flu; a pathological condition that mainly affects birds, horses, and marine mammals, however, the H5N' subtype can infect humans quickly; exposing them to a possible pandemic event. Therefore, the objective of this study was to carry out the molecular docking and three-dimensional homology modeling of flavonoids derived from amentoflavone with H'NI and H5NI neuraminidases of the avian influenza virus. Initially, the 3D structure of H1N1 neuraminidase was obtained by homology. Then, the molecular docking of H1N1 was carried out with six ligands (F36, Ginkgetin, 3S, 3R, 5S, 5R, 6S, and 6R), and subsequently H5N1 and F36, Ginkgetin, 5R, and 6R ligands. Finally, an interaction analysis of the proteinligand complex was performed. The results showed a relationship between the inhibitory activity of ligands and the hydrophobic and hydrogen bridge-type interactions. In addition, an improvement in the inhibitory activity of the ligands for R-type stereochemistry and small bulky substituents was observed. Thus, the experimental evaluation of the 5R and 6R ligands as potential H5N' inhibitors is proposed.
Resumo O vírus influenza A é responsável pela gripe aviária; condição patológica que afeta principalmente pássaros, cavalos e mamíferos marinhos, no entanto, o subtipo H5N' tem a capacidade de infectar humanos rapidamente; assim, expondo-os a um possível evento pandémico. Portanto, o objetivo deste estudo foi realizar o acoplamento e modelagem de homologia tridimensional de flavonóides derivados da amentoflavona com as neuraminidases H1N1 e H5N1 do vírus da influenza aviária. Inicialmente, a estrutura 3D da neuraminidase H1N1 foi obtida por homologia. Em seguida, o acoplamento molecular de H1N1 foi realizado com seis ligantes (F36, Ginkgetin, 3S, 3R, 5S, 5R, 6S e 6R) e, posteriormente, H5NI e os ligantes F36, Ginkgetin, 5R e 6R. Finalmente, uma análise de interação foi realizada nos complexos obtidos. Os resultados mostraram uma relação entre a atividade inibitória e as interações hidrofóbicas e do tipo ponte de hidrogénio formadas entre o sítio ativo das neuraminidases e os ligantes. Além disso, foi observada uma melhoria na atividade inibitória dos ligantes para a estereoquímica do tipo R e pequenos substituintes volumosos. Assim, é proposta a avaliação experimental dos ligantes 5R e 6R como potenciais inibidores do H5NI.
ABSTRACT
Objective To analyze the substitutions at amino acid residues of neuraminidases ( NAs) in influenza B virus strains isolated in Jiangsu province from 2010 to 2012 and to further understand the genetic evolution of NAs in those influenza B virus strains .Methods Forty strains of influenza B virus isolated in Jiangsu province from 2010 to 2012 were screened out for this study .A two-step reverse transcrip-tion PCR ( RT-PCR) was performed to amply the gene fragments encoding the neuraminidases of influenza B virus strains.The PCR products were purified and then sequenced in an ABI 3730XL Genetic Analyzer.The evolutionary characteristics of NA gene were analyzed by using DNAStar , Bioedit, MEGA 5.0 and BEAST 1.8.0 softwares.Results The phylogenetic tree analysis of the NA genes showed that the NAs of 28 Vic-toria strains were derived from the Yamagata lineage .There were reassortments between the Victoria lineage-HA and theYamagata lineage-NA.Some of the strains added a glycosylation site at position 462.No substitu-tion was found in important enzyme active sites and neuraminidase inhibitor resistant sites .The Bayesian MCMC analysis showed that the estimated mean evolutionary rate for NA gene was 1.74×10-3(95%HPD:1.46×10-3-2.06×10-3) substitutions/site/year.The dN/dS ratio (ω), an indicator of selective pressure, was 0.24.Conclusion The important amino acid sites of NA were relatively conservative and the evolution -ary rate for NA gene was low .The dN/dS ratio was less than one , indicating that the NA gene was under pu-rifying selection .
ABSTRACT
Theoretical investigations, using semi-empirical potential functions have been carried out to predict the favoured conformations of the terminal dissaccharide fragments of various sialyloligosaccharides. The proposed conformational similarity for these fragments has been correlated to the binding specificity of neuraminidases. These calculations predict that bacterial neuraminidases have a binding site which can accommodate only two sugar residues and virus neuraminidases have a binding site which can accommodate more than two sugar residues.