Nonspecific factors in monkey tissues and serum causing inhibition of plaque formation and hemagglutination by dengue viruses.

Normal monkey serum and the supernatant fluid from different triturated monkey tissues have been studied for the presence of nonspecific arbovirus hemagglutination and plaque forming inhibitors of dengue viruses types 1, 2, 3, and 4. Hemagglutination inhibition (HI) activity was present in most tissue specimens and demonstrated a significant gradient of effectiveness starting with, respectively, serum, spleen, adrenal, and lung having a high degree of activity, whereas skin, heart, muscle, brain, and liver demonstrated low HI titers. A slightly reversed gradient of effectiveness was obtained for the case of dengue virus inhibition of plaque formation with bile, liver, thymus, spleen, and adrenal giving high 50% plaque reduction titers and heart, muscle, serum, skin, and fat demonstrating little or no activity. Analysis by Sephadex G-200 chromatography and sucrose density gradient centrifugation suggests that HI and plaque formation inhibition are independent activities of normal serum or tissue constituents or both. Also, in addition to the physical methods of characterization, chemical treatment by absorption with kaolin or acetone extraction indicate both phenomena to be the result of the action of lipids or lipoproteins.