Modulation of splenic macrophages, and swine leukocyte antigen (SLA) and viral antigen expression following African swine fever virus (ASFV) inoculation

Abstract

Expression of viral and major histocompatibility complex (MHC) antigens and localization of T cells and macrophages was studied in frozen tissue sections of spleens taken from normal pigs or from pigs inoculated with highly virulent Lisbon 60 (L60), or with moderately virulent Dominican Republic 1978 (DR-II), African swine fever virus (ASFV) isolates. Splenic sections from L60 inoculated pigs exhibited a large decrease in macrophage staining, whereas DR-II infected animals appeared more intensely stained in the macrophage sheath arteries. Class I and class II MHC expression was decreased in spleens from pigs infected with either isolate at 3 day post inoculation (DPI). This was reversed in DR-II inoculated pigs at 4 DPI. Splenic tissue sections from L60 inoculated pigs exhibited only a marginal increase in SLA expression at a later time, 6 DPI. We suggest that the recovery of SLA expression during infection of pigs with ASFV is associated with survival or replacement of macrophages in the spleen leading to an effective immune response against the virus.

African swine fever: A re-emerging viral disease threatening the global pig industry

“…ASFV mainly replicates in myeloid lineage cells, especially antigen presenting cells (APCs) such as monocytes/macrophages and dendritic cells ( Malmquist and Hay, 1960 , Wardley and Wilkinson, 1977 , Gonzalez-Juarrero et al, 1992b , Carrillo et al, 1994 , Gregg et al, 1995a , Gregg et al, 1995b , Sánchez-Cordón et al, 2008 ). There is evidence of modulation of major histocompatibility class II expression in the spleen of pigs infected with a virulent strain of ASFV ( Gonzalez-Juarrero et al, 1992a ). Differences in cytokine secretion following infection of monocytes and macrophages have been reported following infection with attenuated and virulent ASFV ( Franzoni et al, 2017 ).…”

Porcine major histocompatibility complex

“…Regarding the biology of the SLA complex in virally infected swine, the expression in spleen of SLA class I and II antigens was followed in Yorkshire pigs which were inoculated with either a highly virulent or a less virulent African swine fever virus (ASFV) isolate (21). Spleen staining with specific anti-SLA class I and anti class II monoclonals revealed a general decrease of SLA molecule expression at three days post inoculation.…”

Nomenclature for factors of the swine leukocyte antigen class II system, 2005

“…Expression of SLA class II genes helps to differentiate myeloid dendritic cells (DCs) from natural interferonproducing cells or plasmacytoid DCs (5,6). SLA class II genes also control infectious disease responses and influence vaccine efficacy and specificity (1,(7)(8)(9)(10)(11)(12). SLA class II matching is required for acceptance of bone marrow cell and solid organ allografts (13)(14)(15).…”