病毒学报

<正> 牛白血病病毒(BLV)是一种致肿瘤的反转录病毒。在我国乳牛群中BLV的感染率很高,感染牛大多无临床表现,部分牛可引起持续性淋巴细胞增多症(PL),极少数牛可引起淋巴肉瘤(LS)。有不少研究者提出BLV的靶细胞是B淋巴细胞,LS的癌变细胞起源于BLV感染细胞等假设。但迄今还没有一种简易的直观方法能一次检测出外周血中T、E细胞的百分率,带BLV细胞类型和淋巴细胞的BLV感染率。本试验建立一种将B花环试验与放射自显影相结合的新技

A direct anti-surface immunoglobulin rosette test ( B-rosette test ) and an autoradiography technique were developed to identify T and B lymphocytes, and the existence of bovine leukemia virus ( BLV)in these lymphocytes of cows infected with enzootic bovine leukemia ( EBL ) , thus providing a visal method of determining the BLV target cells and calculating the rate of infection of these cells.Formalized sheep erythrocytes sensitized with rabbit anti-bovine Ig were used as indicator cells in B-rosette test, which was designed to determine the percentage of B lymphocytes. A solution of anti-BLV IgG F(ab')2 fragments labelled with 128I was dropped into the B-rosette smears, and autoradiograph was demonstrated with nucleoemulsion 4 to determine the type of BLV-infec-ted lymphocytes.The B-rosette formation rates of 16 immuno-diffusion negative cows and 7 immuno-diffusion-positive but non-PL ( persistent lymphocytosis ) cows, 12 PL cows and 1 LS ( lymphosarcoma ) cows were respectively as follows; 21.84± 4.02%, 33.86±4.15%, 37.54±6.32% and 60%.The B-rosette formation rates of immuno-diffusion-positive and PL cows were much higher than those of immuno-diffusion-negative cows, while that of the LS cow was the highest. This result showed that persistent lymphocytosis in BLV-infected cows is mainly due to increase in B lymphocytes.To demonstrate the BLV antigen on the membrane of BLV-infected lymphocytes, autoradiography were carried out with anti-BLV 125I-F ( ab' )2 preparation. F ( ab')2 fragment was used to avoid non-specific combination of IgG with Fc receptors on B cells. Lymphocyte samples of 32 cows, including 20 immuno-diffusion-positive and 12 immuno-diffusion-negative ones, were examined after they were cultured for 6, 24, 48 and 72 hours. A few black nucleoemulsion particles were observed in the infected cells cult ured for 6 hours, the infection rate of B cell being 6 ± 1.2%. After 24-48 hours of culture, increased numbers of such particles could be found on 30.13±2.159% of B-rosette-formed lymphocytes in positive cows, and no particle in negative samples. The result showed that bovine leukemia virus mainly infected B lymphocytes, a finding consistent with that of many other reports.