Not AvailableClostridium chauvoei causes fatal black quarter infection in cattle and buffaloes. The quorum sensing (QS)
system, a bacterial cell to cell communication process, of the pathogen was characterized in the current
study. The results indicated that C. chauvoei lacked luxS (autoinducer-2) based quorum sensing as
detected by the sensor strain Vibrio harveyi BB170. This was supported by absence of luxS gene in C.
chauvoei genome. However, the genomic analysis indicated the presence of agrBD system in all three
genomes of C. chauvoei available at the NCBI database. The AgrD, which synthesizes QS messenger autoinducing
peptide, was a 44 amino acid protein which shared 59% identity and 75% similarity with AgrD of
C. perfringens strain 13 and 56% identity (20% coverage) with Staphylococcus aureus N315. The functional
cysteine amino acid was conserved in all the strains. The genomic organisation further suggests the
presence of diguanylate cyclase, a gene responsible for synthesis of secondary messenger cyclic di-GMP,
at 3β immediate downstream of agrD gene. The real time expression analysis for agrD gene indicated that
expression was better at 37 C (1.9e3.7 fold increase) compared to a higher temperature of 40 C.
However, stable expression was observed at different growth stages (log and early stationary phase) with
0.8e1.4 fold changes in expression pattern. The results indicate the presence of a constitutively expressed
agrBD quorum sensing system in C. chauvoei.Not Availabl