Bovine recombinant interleukin-2 augments immunity and resistance to bovine herpesvirus infection.
The in vivo administration of bovine recombinant interleukin-2 (rIL-2) was evaluated in calves vaccinated and then challenged with bovine herpesvirus-1 (BHV-1). In Experiment 1, 24 calves were allotted to four groups: control; bovine rIL-2; BHV-1 vaccine (modified-live); and bovine rIL-2 + BHV-1 vaccine. Serum neutralizing antibody titers to BHV-1 were increased sixfold, and virus shedding was fourfold less in calves vaccinated and treated with rIL-2 (25 micrograms/kg, intramuscularly) when compared to calves that received vaccine only. Treatment with rIL-2 induced lymphokine-activated killer activity that was eliminated by pretreating effector cells with complement and a monoclonal antibody (B26A) specific for the sheep red blood cell receptor. The rIL-2 treatment in BHV-1-vaccinated calves increased the calves' ability to withstand a BHV-1 challenge. However, during treatment with rIL-2, calves developed diarrhea and mild fever that abated after IL-2 treatment was stopped. A second experiment was then conducted to determine a dose of rIL-2 that would enhance immunity to BHV-1 without causing adverse side effects. Twenty-five calves were allotted to five groups that received injections of rIL-2 at 0.0, 25.0, 2.5, 0.25, or 0.025 micrograms kg-1 day-1 for 5 days. All calves received a modified-live BHV-1 vaccine. Calves treated with 25.0 micrograms kg-1 day-1 showed similar adverse side effects as in the first experiment but all other calves were normal. Compared to control calves, those treated with 25.0, 2.5, and 0.25 micrograms kg-1 day-1 of rIL-2 had higher (P less than 0.05) serum antibody titers to BHV-1 and following challenge lower (P less than 0.05) BHV-1 titers in nasal secretions; additionally, clinical disease as evidenced by nasal and ocular discharge was less severe (P less than 0.05). In vitro cytotoxic responses against BHV-1-infected bovine kidney cells were increased (P less than 0.05) in calves treated with rIL-2 in a dose dependent manner. These data suggest that bovine rIL-2 at 2.5 to 0.25 micrograms/kg may be an effective adjuvant to immunization.
Reddy
P G
PG
Department of Anatomy, Kansas State University, Manhattan 66056.
Blecha
F
F
Minocha
H C
HC
Anderson
G A
GA
Morrill
J L
JL
Fedorka-Cray
P J
PJ
Baker
P E
PE
D000276:Adjuvants, Immunologic / Q000008:administration & dosage; D000818:Animals; D000914:Antibodies, Viral / Q000096:biosynthesis; D002417:Cattle; D003602:Cytotoxicity, Immunologic; D005069:Evaluation Studies as Topic; D007242:Herpesvirus 1, Bovine / Q000276:immunology; D007241:Infectious Bovine Rhinotracheitis / Q000097:blood / Q000276:immunology / Q000517:prevention & control*; D007376:Interleukin-2 / Q000008:administration & dosage / Q000494:pharmacology*; D007958:Leukocyte Count; D008213:Lymphocyte Activation; D014765:Viral Vaccines / Q000008:administration & dosage
D000276:Adjuvants, Immunologic; D000914:Antibodies, Viral; D007376:Interleukin-2; D014765:Viral Vaccines