Cell-Mediated Immunity to Porcine Reproductive and Respiratory Syndrome Virus in Swine

Abstract

Cell-mediated immunity has been demonstrated to be a necessary component of immunity against viral infection. Methods to detect T-cell mediated immune responses to porcine reproductive and respiratory syndrome virus (PRRSV) infection were established both in vitro as lymphocyte proliferation and in vivo as delayed-type hypersensitivity response (DTH). Optimal conditions for detection of lymphocyte proliferation were determined by testing different antigen concentrations and various stimulation periods. The proliferation response to PRRSV was antigen-specific and dose-dependent. The kinetics of the T-cell proliferation response to PRRSV were analyzed after primary and secondary exposure to virus. Lymphocyte proliferation was first detected at four weeks post-infection (PI), peaked at 7 weeks PI, and declined after 11 weeks PI. The secondary response increased in magnitude. Experiments with blocking antibodies to porcine leukocyte antigens demonstrated that CD4+ T-cells were the major effector cells in the proliferation response. The in vivo response to PRRSV was shown by detection of a dose-dependent DTH reaction in infected pigs after intradermal challenge with UV-inactivated virus. These results demonstrate that pigs generate specific T-cell responses on PRRSV infection and provide a foundation for studying their role in protection.

Porcine Reproductive and Respiratory Syndrome Virus Subverts Repertoire Development by Proliferation of Germline-Encoded B Cells of All Isotypes Bearing Hydrophobic Heavy Chain CDR3

“…Thus, generalized polyclonal B cell activation characteristic of PRRS and LDV could generate autoantibodies to dsDNA, Golgi glycoproteins, and other autoantigens. The immune response to PRRSV is also characterized by a delay in responsiveness (45,46), a surprisingly weak inflammatory response in the lung (47,48), and the need for 150 days to clear the infection (4). This delay is believed to increase susceptibility to secondary infections that may also interfere with the effectiveness of vaccines (49 -51).…”

Passive Transfer of Maternal Mycoplasma hyopneumoniae -Specific Cellular Immunity to Piglets

“…Piglet blood was diluted 1:1 in sterile PBS to improve cell recovery yield. Colostral and blood lymphocytes were isolated by Ficoll density centrifugation as described previously (10,2). Cells were stained with the membrane stain carboxy fluorescein succinylimidyl ester (CFSE) (ICT, Bloomington, MN) to evaluate antigen-specific proliferation (11).…”

Antibody Repertoire Development in Fetal and Neonatal Piglets: XIX. Undiversified B Cells with Hydrophobic HCDR3s Preferentially Proliferate in the Porcine Reproductive and Respiratory Syndrome

“…An increase in the numbers of B cells and CD8 ϩ cells in bronchoalveolar lavage (BAL) can be seen as early as 5 dpi without effect on CD4 ϩ cells (26,27). PRRSVspecific T cell responses appear delayed and are not detected until 28 days dpi (28,29). Blocking studies indicate the delayed T cell response is largely due to a delayed response of CD4 ϩ T cells (28,29).…”

“…PRRSVspecific T cell responses appear delayed and are not detected until 28 days dpi (28,29). Blocking studies indicate the delayed T cell response is largely due to a delayed response of CD4 ϩ T cells (28,29). Depletion of CD8 ϩ cells had little effect on clinical symptoms and, not surprisingly, on PRRSV-specific Abs (30).…”