Migration of simian virus 40 from the vascular system into the glomerular mesangial region

The behavior of simian virus 40 (SV40) injected into the vascular system was investigated in the rat glomerulus. The kidney was perfused via the abdominal aorta with a serum-free culture medium for 5 min, with PBS solution containing SV40 and then with the same medium for 15 min at 37 degrees C. In the glomeruli, SV40 particles were detected in the lumen of the capillaries, fenestrations of endothelial cells and lamina rara interna of the glomerular basement membrane. They were also found in the mesangial matrix and mesangial cells. Invaginations of their membrane were observed on several surface areas where SV40 particles were localized close to the surface. Similarly, when the particles were injected into the tail vein, they were detected in the lamina rara interna, the mesangial matrix, and in vacuoles of mesangial cells at 2 h after the injection. These results indicate that SV40 particles migrate from the vascular system into the mesangial matrix, and are then endocytosed in vivo by mesangial cells.