Molecular typing of Dichelobacter nodosus in ovine footrot and expression of its fimbrial biogenesis protein PilQ as a candidate footrot vaccine.

Abstract

Background: Footrot is a highly contagious disease of the feet in sheep and goats.

Aims: The study was conducted to determine the serogroup distribution of Dichelobacter nodosus in sheep affected by footrot on organized farms and flocks reared by farmers across four districts of the Kashmir Valley.

Methods: Sheep from randomly selected organized farms and flocks raised by farmers and the Bakerwal tribes were screened for footrot lesions based on clinical signs, particularly lameness. Two hundred sixty swab samples were collected from sheep exhibiting footrot lesions, and D. nodosus infection was confirmed using 16S rRNA-specific PCR. For serogroup subtyping, multiplex PCR was performed. Furthermore, we utilized the pET28a expression vector to clone and express the outer membrane fimbrial protein antigen, which was confirmed using SDS-PAGE and Western blot analysis.

Results: D. nodosus was detected in 149 samples by 16S rRNA-specific PCR. Serogroups B and E were detected in 85.9% and 10.74% of positive samples, respectively, while both serogroups were detected in 3.36% of the samples. The outer membrane domain containing the major antigenic epitopes of the pilQ gene of D. nodosus was successfully cloned into the pET28a expression vector.

Conclusion: The prevalence of ovine footrot was found to be low during the study period. Serogroup B of D. nodosus was found to be predominant, while serogroup E was detected exclusively in some isolated flocks reared by farmers. The pilQ gene was successfully expressed in Escherichia coli and purified to near homogeneity, making it suitable for further exploitation as a serogroup-independent vaccine candidate against footrot.