03668naa a2200373 a 450000100080000000500110000800800410001902400480006010000220010824501520013026000090028252025860029165000210287765000150289865000150291365000180292865000260294665000190297265000190299165000190301065000170302965000110304665300210305765300210307865300240309970000210312370000150314470000180315970000110317770000180318870000190320670000180322577300510324315293322023-08-25       1996    bl uuuu     u00u1 u    #d7 ahttps://doi.org/10.1006/viro.1996.01532DOI1 aMERTENS, P. P. C.  aEnhanced infectivity of modified bluetongue virus particles for two insect cell lines and for two Culicoides vector species.h[electronic resource]  c1996  aPrevious studies{Mertens et al., Vico/ogyJ57,375-386, 1987) have shown that removal of the outer capsid layer from bluetongue virus (BTV) significantly reduces (approximately x 10-4) the infectivity of the resultant core particle for mammalian cells (BHK 21 cells). In contrast, the studies reported here, using a cell line (KC cells) derived from a species of Culicoides that can act as a vector for BTV (Culicoides variipennis), demonstrated a much higher infectivity of core particles than that in mammalian cells (approximately x 103). This increase resulted in a specific infectivity for cores that was only 20-fold less than that of purified desegregated virus particles (stored in the presence of 01% sodium-N-lauroylsarcosine (NLS)) Removal of this detergent causedintact virus particle aggregation and (as previously reported) resulted in an approximately 1 logo drop in the specific infectivity of those virus particles which remained in suspension. In consequence the specific infectivity of core particles for the KC cells was directly comparable to that of the intact but aggregated virus. These data are compared with the results from oral infectivity studies using two vector species (C. variipennis and Culicoides nubecu/osus), which showed similar infection rates at comparable concentrations of purified cores, or of the intact but aggregated virus particles (NLS was toxic to adult flies). The role of the outer core proteins (VP7) in cell attachment and penetration, as an alternative route of initiation of infection, is discussed Previous studies (Mertens et a/., Virology 157, 375-386,1987) also showed that the outer capsid layer of BTV can be modified by proteases (including trypsin or chymotrypsin), thereby generating infectious subviral particles (ISVP). The specific infectivity of ISVP for mammalian cells (BHK21 cells) was shown to be similar to that of desegregated virus particles. In contrast, we report a significantly higher specific infectivity of ISVP but not of the intact virus (approximately x 100) for two insect cell lines (KC cells and C6/36 mosquito cells (derived from Aedes albopictus) In oral infection studies with adults of the two vector species, ISVP produced the same infection rate at approximately 100-fold lower concentrations than either core particles or the intact but aggregated virus particles. The importance of mammalian host serum proteases, or insect gut proteases, in modification of the intact virus particle to form ISVP and their role in initiation of infection and the vector status of the insect is discussed.  aBluetongue virus  aCell lines  aCricetinae  aPathogenicity  aProteinase inhibitors  aSheep diseases  aViral proteins  aDoença Animal  aLíngua Azul  aVírus  aCulicoides vetor  aLinhagem celular  aProtease Inhibitors1 aBURROUGHS, J. N.1 aWALTON, A.1 aWELLBY, M. P.1 aFU, H.1 aO'HARA, R. S.1 aBROOKES, S. M.1 aMELLOR, P. S.  tVirologygv. 217, n. 2, p. 582-593, Mar. 1996.