MODULATION OF IMMUNE CELL-POPULATIONS AND ACTIVATION MARKERS IN THE PATHOGENESIS OF AFRICAN SWINE FEVER VIRUS-INFECTION

African swine fever (ASF) virus induces immune cell alterations that m ay be detected by changes in peripheral blood cells phenotypic antigen s and activation markers which were examined by flow cytometry, analyz ing both cell proportion and/or expression intensity of superficial an tigens. These studies were conducted in pigs with experimental acute o r chronic ASF infection to determine whether changes among important s urface activation markers and phenotypic antigens, and their correlati ve lymph node status, reflected similar or disparate aspects of immune pathology. In acute infection produced by virulent viruses, macrophag e and B lymphocyte populations decreased in peripheral blood after a s hort activation period at the beginning of the infection. A significat ive decrease of interleukin 2 receptor (IL 2R) expression was also obs erved in those pigs. These variations correlated with lymph node cell depletion due to an intense lymphoid cell death by apoptosis, affectin g mainly the B lymphocyte subpopulation as determined by immunohistoch emistry. Nevertheless, pigs infected with an attenuated isolate underg oing chronic persistent infection, presented a distinct pattern of mod ification, according with a different clinicopathological evolution. C hanges consisted in systemic immune activation coincident with the hig hest viremia titer, with an augmentation in CD8(+) T lymphocyte, macro phage, and B cell populations, and MHC (major histocompatibility compl ex) antigens. Percentage elevation of circulating immune subpopulation s was accompanied by cell accumulation with lymphoid hyperplasia but a conserved distribution of B lymphocytes in lymphoid organs of chronic ally infected pigs. (C) 1997 Elsevier Science B.V.