Poxvirus-induced immunostimulating effects on porcine leukocytes

Area of Science:

• Immunology
• Virology
• Veterinary Medicine

Background:

• Inactivated parapox ovis virus (Baypamun) prevents stress-mediated diseases in animals.
• The underlying immune activation mechanism of inactivated poxviruses is not well understood.

Purpose of the Study:

• To investigate the in vitro immune-stimulating capacity of inactivated poxviruses in porcine immune cells.
• To identify the specific immune cells targeted by inactivated poxviruses and their response.

Main Methods:

• Testing eight inactivated poxvirus strains from three genera (Orthopoxvirus, Avipoxvirus, Parapoxvirus) on porcine immune cells in vitro.
• Assessing phagocytosis, oxidative burst, natural killer cell activity, cytokine release (interleukin-2, alpha interferon, gamma interferon), and cell proliferation.
• Utilizing flow cytometry and cell sorting to identify responding cell populations.

Main Results:

• Poxviruses did not enhance phagocytosis, oxidative burst, or natural killer cell activity.
• Significant increases in interleukin-2, alpha interferon, and gamma interferon release were observed.
• Strong T-helper cell proliferation was detected, with activated cells showing a CD4(high) CD25(+) MHC class II-positive phenotype.

Conclusions:

• All tested inactivated poxviruses demonstrated immunostimulating capacity in vitro.
• T-helper cells are the primary responders to inactivated poxviruses, secreting key cytokines.
• In vitro immune effects provide a potential explanation for the in vivo efficacy of inactivated poxviruses.