ABSTRACT
Langat (LGT) virus, initially isolated in 1956 from ticks in Malaysia, is a naturally occurring nonpathogenic virus with a very close antigenicity to the highly pathogenic tick-borne encephalitis (TBE) Western subtype virus and TBE Far Eastern subtype virus. NS3, the second largest viral protein of LGT virus, is highly conserved among flaviviruses and contains a characteristic protease moiety (NS3 pro). NS3 pro represents an attractive target for anti-protease molecules against TBE virus. We report herein a purification method specially designed for NS3 pro of LGT using a strategy for proper refolding coupled with the enzymatic characterisation of the protein. Different p-nitroanilide substrates, defined on canonic sequences for their susceptibility to Ser-protease, were applied to the proteolytic assays of the protein. The highest values were obtained from substrates containing an Arg or Lys (amino acid) residue at the P1 position. This purification method will facilitate the future development of reliable testing procedures for anti-proteases directed to NS3 proteins.
Subject(s)
Encephalitis Viruses, Tick-Borne/enzymology , Serine Endopeptidases/metabolism , Viral Nonstructural Proteins/metabolism , Amino Acid Sequence , Animals , Chromogenic Compounds/metabolism , Encephalitis, Tick-Borne/enzymology , Encephalitis, Tick-Borne/virology , Malaysia , Molecular Sequence Data , Protease Inhibitors/therapeutic use , Protein Folding , RNA Helicases , Sequence Alignment , TicksABSTRACT
In many insect species, adult emergence spreads over several years because of the existence of prolonged diapause in certain individuals. From stochastic models, we show that diversified bet-hedging strategies (mixed strategies with emergence after 1 or 2 yr) are more fit than simple diapause strategy (emergence after 1 yr) or fixed prolonged diapause strategy (emergence after 2 yr) in isolated chestnut weevil populations. This conclusion applies to a large range of survival rates in prolonged diapause and is insensitive to initial conditions, magnitude of temporal autocorrelation, distribution of demographic parameters, and quoted values of population size limitation. However, the shape of the fitness distribution as a function of prolonged diapause frequency changes greatly in the absence of population size limitation. Whatever the survival rate during prolonged diapause, we find that there is no genotypic advantage to extending diapause for all chestnut weevil larvae to more than 1 yr. Our models predict selection of bet-hedging strategies over a large range of prolonged diapause frequencies. This result is consistent with the existence of several mixed strategies in a population. Emergences after 3 yr are not crucial for selection or for the dynamics of mixed strategies in the chestnut weevil.
