Involvement of CD8⁺T Cells in Delayed-type Hypersensitivity Responses against Bovine Leukemia Virus (BLV) Induced in Sheep Vaccinated with Recombinant Vaccinia Virus Expressing BLV Envelope Glycoprotein

Abstract

Delayed-type hypersensitivity responses against bovine leukemia virus (BLV) envelope glycoprotein (gp60) were induced in the skin of sheep vaccinated with recombinant vaccinia virus (RVV) expressing BLV glycoprotein. The lesions were characterized by marked infiltration of lymphocytes, slight migration of neutrophils, eosinophils, and macrophages in the dermis to hypodermis, and partial intercellular edema in the reticular layer. Immunohistochemical analysis with monoclonal antibodies demonstrated that the lymphocytic infiltrates consisted mainly of CD8+ T cells (53.7-55.8% at 48 hours post-challenge of BLV), CD4+ T cells (24.7-26.7%), and B cells (11.5-16.9%). The role of CD4+ and CD8+ T cells in suppressing BLV growth in RVV-vaccinated animals is discussed.

Bovine leukemia virus: current perspectives

“…[91][92][93] Vaccination of mice and sheep using the rVV coding for BLV gp51 (BLVgp51-rVV) resulted in protective immunity, with the characteristics of a type 1 response. [94][95][96][97][98] These observations are in agreement with the notion that animals that control the virus express higher levels of interleukin-12 and interferon-gamma and lower levels of interleukin-10.…”

Preventive and Therapeutic Strategies for Bovine Leukemia Virus: Lessons for HTLV

“…However, the BLV proviral loads were decreased in vaccinated sheep. An efficient immune response correlated with type 1 helper T cell proliferation and delayed hypersensitivity with predominant involvement of CD8 cytotoxic T lymphocytes [214,215,217]. In two other studies, similar RVV- env vaccines induced a strong humoral and CD4+ T cell response and protected against BLV challenge [209,210].…”

T cell proliferative response to bovine leukaemia virus (BLV): identification of T cell epitopes on the major core protein (p24) in BLV-infected cattle with normal haematological values

“…Callebaut et al (1993) reported the existence of helper T cell epitopes on the gp51 envelope glycoprotein in BLV-infected cattle. Ohishi et al (1991) and Okada et al (1993) observed the presence of CD4 ÷ and CD8 + T lymphocytes in delayedtype hypersensitivity skin reactions from sheep vaccinated with recombinant vaccinia virus expressing gp51 envelope protein and challenged intradermally with BLV virions. They suggest that CD4 ÷ T cells might be involved in the BLV growth suppression by releasing lymphokines such as interferon y.…”