Virus da lingua azul : estudo do antigeno viral, produzido a partir do soro tipo 4, para fins de diagnostico sorologico

AUTOR(ES)
DATA DE PUBLICAÇÃO

1990

RESUMO

In the present study a strain of Bluetongue virus, serotype 4 (BTV-S4), when adapted to BHK 21, clone 13 and to VERO cell lines has shown a distinctive cytophatic effect between 72 h and 96 h after inoculation, with titres ranging from 10 POT. 3.6 to 10 POT. 3.6 DICT 50%/ml. After a high speed centrifugation of the packed infected cells the viral particles were purified by ultracentrifugation using CsCIgradient, showing density around 1.38 g/cm POT. 3 . In the electron microscope, two types of spherical particles were observed one with a mean diameter of 54.99 + ou - 0,12 run corresponding to the virion and the other of 49.68 + ou - 0,08 nm, corresponding to the nucleocapsid. The electrophoretic profiles of the RNAextracted from BTV-S4 showed ten segments with MW between 2.96 x 10 POT. 6 d (segment 1) to 0.49 X 10 POT. 6 d (aegment 10). With regard to the atructural proteina, the MW a180 varied from 103.69 X 10 POT. 3 d (VP1) to 30.24 x 10 POT. 3 d (VP7). The aoluble antigen (SA) produced from culture supernatanta of BTV-infected VERO cells and concentrated by aequential ultrafiltration with membranes with cut-off values 10.000 and 25.000, when compared with the antigens produced by by the agar gel the NADC and commercially, showed total identity immunodiffusion (AGID) test forming a nitid and confluent precipitation line without any spur. The electrophoretic protein profile of the 3 antigens was quite ainÜlar suggesting an identical antigen preparation. A semiquantitative evaluation of thia antigen by aingle radial immune diffusion test showed a relative potency slightly higher than the NADC and equal to the commercial one. Furthermore checking block titration revealed that routine dilution of this antigen to be used in AG1D for the serological diagnosis of BT should be 1/2. The proteie eomponent of the AS. main responsible for the IDGA reaction, showed a MW around 60.00 x 10 POT. 3 d suggesting that this might be, probably, the NS1 (P5a) protein or the VP5. The indireet immunofluorescent technique (IIFT) carried out with BTVinfected VERO cells using bovine and ovine sera and anti-1gG conjugates showed a granular intracytoplasmatie fluorescenee and in some cells this fluorescence was observed only on cellular membranes. Sera from 190 bovine and 72 ovine were examined by AG1D and 11FT. In the AG1D 134 samples were positive for BTV antibodies and 128 were negative, whereas in the 11FT 137 sera were positive for BTV antibodies and 125 were negative. Statistical analysis of these data showed close agreement between the two techniques, regardless of the kind of sera examined. 1n the 11FT, high sensitivity, specificity and predictable values for positive and negative results were found compared with the 1DGA, which means, that both techniques can routinely be used in epidemiologic evaluation studies of BT in our country. The 11FT offers an additional advantage as it may be used to detect viral antigens in BT-infected cell lines.

ASSUNTO(S)

virologia veterinaria lingua azul (veterinaria)

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