Fowlpox Virus in Chicken’s Skin: Persistence and the Local Immune Response at the Site of Inoculation

Background: Fowlpox virus (FPV) has been used as a vector for many years. To date, surprisingly, very little data exist on the persistence of fowlpox vaccines in chicken tissues, or what kind of immune cells respond to vaccination at the site of inoculation. Although both humoral and cellular- mediated immunity (CMI) play a part in overall immunity against FPV, little is known regarding the cell-mediated immune responses to FPV infection. Aim: The main aim of this paper was to measure persistence of fowlpox vaccine in skin tissues following vaccination. Methods: One-day-old chicks were vaccinated with Fowlpox virus FP9. Skin samples were collected from the site of inoculation for several days following vaccination to assess the presence of for FPV, as well as other immune cells including macrophages, CD4+ T cells, CD8+ T cells, and B cells. Results: Results showed that FPV does not persist for long, and is cleared by 6 days post-vaccination (dpv). The response of immune cells (macrophages, B cells, CD4+ and CD8+ T cells) that infiltrated the site of vaccination was assessed. Conclusion: The results in this paper reflected the response at the site of inoculation following single vaccination, therefore, further studies regarding viral persistence and infiltration of immune cells at the site of inoculation after booster vaccination should be done.