Development and antigen specificity of the lymphoproliferation responses of pigs to pseudorabies virus: dichotomy between secondary B- and T-cell responses.
To better understand the contribution of T cells to the immunity of pigs to pseudorabies virus (PRV), we examined the lymphoproliferation response to this virus. Depletion studies demonstrated that both CD2+CD8+ and CD2+CD4+ cells contributed to lymphoproliferation, but to varying degrees upon stimulation with live and ultraviolet (UV) light-inactivated PRV. Flow cytometric analysis revealed the emergence of both CD2+CD8+ and CD2+CD4+ lymphoblastoid cells. To examine the contribution of specific viral proteins, we prepared immortalized porcine B cells of haplotype d/d that stably expressed a single PRV protein, and used these cells for in vitro stimulation of lymphocytes from PRV-immune miniature pigs of the same haplotype. Cells expressing PRV gB or gC induced proliferation. An immunization/challenge experiment showed that the lymphoproliferation response was stronger upon immunization with the virulent NIA-3 strain than with the attenuated Bartha strain. Upon challenge inoculation, the NIA-3-immunized pigs were almost completely immune, in contrast to the Bartha-immunized pigs. Such poorly protected pigs showed secondary B- and T-cell immune responses upon challenge. In contrast, the better protected NIA-3-immunized pigs did not show a secondary B-cell response. However, they developed a secondary lymphoproliferation response, which was quicker and stronger than in the Bartha-immunized pigs. This dichotomy between secondary B- and T-cell responses indicates that an effective T-cell memory response is able to quickly eliminate challenge virus in immune pigs, so preventing a secondary B-cell response.
Kimman
T G
TG
Department of Mammalian Virology, Institute for Animal Science and Health (ID-DLO), Lelystad, The Netherlands.
De Bruin
T M
TM
Voermans
J J
JJ
Peeters
B P
BP
Bianchi
A T
AT
D000818:Animals; D000917:Antibody Formation; D001402:B-Lymphocytes / Q000276:immunology*; D018801:CD2 Antigens / Q000276:immunology; D015704:CD4 Antigens / Q000276:immunology; D016827:CD8 Antigens / Q000276:immunology; D000939:Epitopes / Q000276:immunology*; D007111:Immunity, Cellular; D008212:Lymphocyte Depletion; D011557:Pseudorabies / Q000276:immunology*; D013552:Swine / Q000276:immunology*; D013556:Swine, Miniature / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*
D018801:CD2 Antigens; D015704:CD4 Antigens; D016827:CD8 Antigens; D000939:Epitopes