COUNTERMEASURES TO PREVENT THE PORCINE RESPIRATORY DISEASE COMPLEX (PRDC)
Location: Virus and Prion Research Unit
Title: G-CSF Analogue Treatment Increases Peripheral Neutrophil Numbers in Pigs - a Potential Alternative for In-Feed Antibiotics
Submitted to: Research Workers in Animal Diseases Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: October 15, 2010
Publication Date: December 5, 2010
Citation: Loving, C.L., Brockmeier, S.L., Bayles, D.O., Greenlee, J.J., Lager, K.M., Kehrli, Jr., M.E. 2010. G-CSF analogue treatment increases peripheral neutrophil numbers in pigs - a potential alternative for in-feed antibiotics. Conference of Research Workers in Animal Diseases. Paper No. 140.
Immunomodulators is a promising area for therapeutic, prophylactic, and metaphylactic use to prevent and combat infectious disease during periods of peak disease incidence. Granulocyte colony-stimulating factor (G-CSF) enhances neutrophil production and release from the bone marrow and is already licensed for use in humans for treatment of neutropenia and prevention of postoperative infections. Its prophylactic use has been experimentally shown to reduce the incidence of coliform and staphylococcal mastitis in cows. However, a limitation of cytokines as immunomodulators is their short half-life thus limiting their usefulness as a one-time injectable in production animal medicine. Here we report on a porcine G-CSF analogue created on the basis of previous findings of two point mutations in human G-CSF that resulted in increased in vitro potencies and increased ligand half-life. Our initial investigations were on the effects of G-CSF to induce and sustain a neutrophilia and leukocytosis in pigs. The G-CSF products tested included both the human product Neulasta (pegfilgrastim) as a subcutaneous injection and a mutated form of porcine G-CSF delivered via a replication-defective human adenovirus 5 vector (Ad5/G-CSF). Pigs given a single subcutaneous injection of Neulasta at 5 ug/kg, 25 ug/kg, 50 ug/kg or 100 ug/kg had a dose-dependent peak neutrophilia by 1 day post injection that ranged from an average of a 4-, 7-, 10- or 16-fold increase in neutrophil counts, respectively. Neutrophil counts following Neulasta treatment remained elevated compared to pretreatment values for 4-7 days, again in a dose-dependent manner. By comparison, pigs given one injection of the Ad5/G-CSF intramuscularly (10**10 PFU) also had a neutrophilia (>2-fold increase) by 1 day post injection, however, the neutrophil counts peaked between days 3 to 11 post-treatment with a range of 6- to 8-fold increases in peak neutrophil counts. Neutrophil counts remained elevated compared to pretreatment values for >14 days. Studies examining the effectiveness of G-CSF treatment on the prevention of disease with common swine pathogens are ongoing. G-CSF has the potential to eliminate or reduce the need for antibiotic usage for the prevention or treatment of infectious disease, especially during typical times of stress and pathogen exposure such as post-weaning and post partum.