Ovine balanoposthitis: observations on the microbiome and immunoglobulin response

The incidence of ulcerative balanoposthitis (UB) in rams contributes to significant economic losses in the national sheep population. Understanding the immune response in the reproductive tract can aid in developing preventive measures. This study aimed to characterise the immunoglobulin profiles and microbial diversity in the reproductive tract of rams affected by UB, providing insight into the immune responses to this disease. Serum and glans tissue samples from healthy and UB-affected rams were analysed using an ELISA approach to quantify IgG, IgA, and IgM levels. The microbial diversity in nasal, penile swabs, and smegma samples was assessed using an ARISA approach. Significant differences (p ≤ 0.001) were observed between the systemic and localised immune responses. UB-affected rams exhibited higher IgG and IgM levels but lower IgA levels in both serum and glans tissue compared to healthy rams. The study confirmed UB-induced shifts in the microbiome, with significant differences in microbial diversity indices in nasal, penile, and smegma samples. Specifically, there were changes in the nasal fungi Shannon (p = 0.047) and Simpson (p = 0.038) indices, the penile Shannon (p = 0.015) and Simpson (p = 0.006) bacterial indices, and the smegma bacterial species number index (p = 0.042). Correlations between microbial populations and immunoglobulin profiles indicated an interactive immune response in different health statuses. This study highlights the need to understand the immune system of the lower reproductive tract and its interaction with commensal organisms to develop therapeutic immunomodulators for preventing UB in sheep.