Abstract
Aim:Identification of different serogroups of Dichelobacter nodosus prevailing in the region and to understand the degree of genetic heterogeneities among the different isolates of D. nodosus.Materials and Methods:A total of 150 exudate samples of footrot lesions with a lesion score of 2-4 were collected from naturally infected sheep. The samples were screened by polymerase chain reaction (PCR) targeting D. nodosus specific 16srRNA. Of 150 samples screened, 70 samples were found to be positive. The positive samples were attempted for isolation of D. nodosus, out of which 16 isolates were recovered. All the isolates were subjected to serogrouping by multiplex PCR targeting fimA gene using A-I serogroup specific primers.Results:Of 16 isolates, 7 (43.75%) isolates were serogroup B, 4 (25.00%) isolates were serogroup A, 3 isolates (18.75%) were serogroup I and 2 (12.5%) isolates yielded both serogroup A and B. phylogenetic analysis was performed using neighbor-joining algorithm of the ClustelX2 software in order to study whether the serogroups isolated in the present investigation differed genetically from other published serogroups. The fimA gene sequence of present isolates of serogroups A, B, and I were segregated into three distinct groups with high bootstrap values. The serogroup B clustered with Australian isolate of serotype B1 suggesting high genetic similarity of the present isolate with serotype B1.Conclusions:The clinical samples were collected from suspected outbreaks of footrot and identified the prevalence of D. nodosus by PCR targeting 16srRNA gene. Identified serogroups A, B, and I from different districts of Andhra Pradesh. The phylogenetic analysis will help for the tentative identification of serotypes present in the serogroup and to understand the degree of genetic heterogeneities among the different isolates of D. nodosus.
Highlights
Footrot is a specific contagious disease of the feet of sheep and goats, it has been reported in cattle, horses, pigs and deer
The clinical samples were collected from suspected outbreaks of footrot and identified the prevalence of D. nodosus by polymerase chain reaction (PCR) targeting 16srRNA gene
The phylogenetic analysis will help for the tentative identification of serotypes present in the serogroup and to understand the degree of genetic heterogeneities among the different isolates of D. nodosus
Summary
Footrot is a specific contagious disease of the feet of sheep and goats, it has been reported in cattle, horses, pigs and deer. It is an infectious syndrome caused by the synergistic action of certain bacterial species, of which Dichelobacter nodosus is the main transmitting agent [1]. D. nodosus is an anaerobic, Gram-negative, rodshaped bacterium, with characteristic knobs at each end, and is often heavily fimbriated. Nodosus into 10 serogroups (A-I and M) based on K-type agglutination [2]. These serogroups are further divided into 19 serotypes based on cross-absorption tests
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