African swine fever virus specific porcine cytotoxic T cell activity

Abstract

African swine fever virus (ASFV) specific, cytotoxic T lymphocyte (CTL) activity has been studied in a protection model in which SLA inbred miniature swine are experimentally inoculated with a naturally occurring, non-fatal ASFV isolate (NHV). Peripheral blood mononuclear cells (PBMC) from such infected swine show significant activity in CTL assays, using cultured ASFV-infected porcine blood derived macrophages as target cells. This CTL activity is elicited from PBMC by in vitro restimulation of effector cells with low doses (multiplicity of infection = 0.1) of the homologous virus isolate for 48 to 72 h. For SLAc/c effectors, this CTL activity appears to be SLA class I restricted because (1) blocking target cell antigens with monoclonal antibodies (mAb) against SLA class I antigens causes a major reduction in CTL activity; (2) there is preferential lysis of SLA class I matched, ASFV infected targets; and (3) depletion of effector cells with CD8 specific mAb and complement causes a reduction in CTL activity. The CTL activity is ASFV specific for all pigs tested in that infected macrophages are preferentially lysed as compared to normal (non-infected) cultured macrophages or macrophages infected with hog cholera virus (HCV). Lysis of macrophages infected with different ASFV isolates revealed that there is marked lysis of macrophages infected with the virulent L60 isolate but less lysis of macrophages infected with the DR-II and Tengani isolates. In summary, our data show that ASFV specific CTL activity is triggered in swine infected with the NHV ASFV isolate.

Classical swine fever virus-specific cytotoxic T lymphocytes and identification of a T cell epitope

“…The exclusive lysis of autologous but not of heterologous target cells as well as the blocking of virus specific lysis by monoclonal antibodies against CD8 or MHC class I antigen indicated that the recognition of virus-infected targets by CSFV-specific CTL is a classical MHC class Irestricted process. Although inhibition with MAb 2.27.3a (anti-MHC class I) was only partial, the result is consistent with previously described inhibition of CTL activity in other studies (Martins et al, 1993). The virusspecific CTL described here belong to the CD4-CD6+CD8 + T lymphocyte subpopulation as demonstrated in chromium release assays with separated effector cell populations.…”

“…Therefore antigen presentation to CD4 + T lymphocytes does not occur under these conditions. Interestingly, the effector cells showed a high nonspecific lysis of non-infected target cells which has been previously described in conjunction with other viral infections of swine (Martins et al, 1993). This nonspecific lysis may be due to either non-specific activity of the effector cells or lymphokine-activated killer cells (LAK).…”

Membrane markers of the immune cells in swine: an update

“…Specific identification of the various subpopulations of leukocytes enables improved investigations of the immune response to various porcine infections such as Actinobacillus pleuropneumoniae, African swine fever virus, classical swine fever virus, porcine reproductive and respiratory syndrome virus (PRRSV) and Aujeszky disease virus [6, 41,76,110,116,127,137,213]. An understanding of these interactions is essential for the development of new generations of vaccines.…”

Humoral and cell-mediated immune responses of d/d histocompatible pigs against classical swine fever (CSF) virus

“…However, in some instances where neutralizing antibodies were not detectable, a relative protection was observed suggesting a possible protective role for T cells [21]. Cellular immune responses, especially virus-specific cytotoxic T lymphocytes (CTL), have been shown to represent an important defense mechanism against African Swine Fever Virus (ASFV) infection in pigs [13]. These mechanisms have also been demonstrated for the Pestiviruses bovine viral diarrhea virus [3] and border disease virus [34].…”