Effects of inactivated parapoxvirus ovis on the cumulative incidence of pneumonia and cytokine secretion in foals on a farm with endemic infections caused by Rhodococcus equi.

This research looks into whether injecting foals with inactivated parapoxvirus ovis (IPPVO) can reduce the chances of pneumonia and boost the production of certain immune cells. The study’s results show that there was no significant difference in the development of pneumonia between foals treated with IPPVO and those given a placebo, but treatment with IPPVO significantly increased the number of IFN-γ secreting cells in foals between 7 to 14 days old.

Research Methodology

• Fifty-nine foals were studies and randomly bucketed into two groups: one to be treated with IPPVO, the other to be given a placebo.
• Within the first 24-48 hours of life, the foals were given their assigned treatment via intramuscular injection, with follow-up injections at 24 hours and eight days later.
• The researchers tracked the quantity of IFN-γ- and IL-4-secreting cells by using a validated ELISPOT assay on blood mononuclear cells collected when the foals were between 1-14 days old.
• The foals’ health was monitored on a daily basis for signs of pneumonia, and lung lesions were checked biweekly via ultrasound.

Results and Findings

• No significant difference was found in the incidence of pneumonia between the foals treated with IPPVO (16 out of 28) and those given the placebo (14 out of 31).
• The number of IFN-γ- and IL-4-secreting cells were detected only in 22 and 15 foals respectively.
• A significant influence of the IPPVO treatment on the number of IFN-γ-secretion cells was noted in foals that were 7- to 14-days-old, but not in younger foals.
• No significant effects of IPPVO treatment were found on the number of IL-4-secreting cells.
• The odds of detecting IFN-γ (5.1; 95% CI: 1.5-15) and IL-4 (3.5; 95% CI: 1.1-12) were significantly higher in foals aged 7-14 days as compared to younger foals, irrespective of whether they were treated with IPPVO or the placebo.
• There was no significant association found between the early secretion of IFN-γ or IL-4 and the subsequent development of pneumonia.

Conclusion

The administration of IPPVO showed a significant impact on the number of IFN-γ-secretion cells, but not IL-4-secreting cells, in foals of certain ages, however it doesn’t have a significant effect on the incidence of pneumonia in the foals. In addition, early IFN-γ or IL-4 secretion is not linked with the development of pneumonia later in life.