Indrani Karunasagar

Prevalence of human pathogenic enteric viruses in bivalve molluscan shellfish and cultured shrimp in south west coast of India

The prevalence of human enteric viruses in bivalve molluscan shellfish and shrimp collected off the south west coast of India was studied to assess the extent of fecal pollution of coastal environment. Out of 194 samples analyzed, 37% of oyster, 46% of clam and 15% of shrimp samples were positive for enteroviruses (EV). Adenoviruses (ADV) were detected in 17% of oyster and 27% of clam samples. However, other enteric viruses such as noroviruses (NoV) and hepatitis A virus (HAV) were not detected in any of the samples. High prevalence of EV and ADV was noticed between May to December. Thirty four percent of oyster and 49% of clam samples showed fecal coliform values higher than the limit. MS-2 phage was detected in 57% of oyster and 73% of clam samples. The presence of MS-2 phage and human enteric viruses showed association while fecal coliforms and enteric viruses showed no association. However, 17 samples, which were positive for enteric viruses (EV and ADV), were negative for MS-2 phage.

In silico identification and characterization of novel drug targets and outer membrane proteins in the fish pathogen Edwardsiella tarda

The complete genome of the fish pathogen Edwardsiella tarda and the host Danio rerio (zebrafish) was subjected to subtractive genome analysis with the objective of identifying potential drug targets and vaccine candidates. The homologous proteins were excluded to prevent any chance of cytotoxic cross-reaction with the host. The nonparalogous proteins were analyzed for sequence homology with the Database of Essential Genes to determine the essentiality of the proteins for the bacteria. These essential proteins were further analyzed to predict the meta- bolic pathways in which they were involved. Cellular localization analysis was carried out to determine the possibility of the protein being present in the outer membrane. Outer membrane proteins may play an important role in the interaction with hosts and in bacterial pathogenicity. The study identified 171 of 3986 proteins as potential drug targets. The study also identified seven novel outer membrane proteins.

Draft Genome Sequence of Multidrug Resistant Salmonella enterica serovar Weltevreden Isolated from Seafood

Salmonella enterica subsp. enterica serovar Weltevereden is the most frequent serovar isolated from Asia. Here, we report a draft genome sequence of multidrug resistant Salmonella Weltevreden 9 isolated from seafood. Whole-genome of this isolate and annotation will help enhance the understanding of this pathogenic multidrug-resistant serovar.

Outer membrane protein secretin of type III secretion system of Vibrio vulnificus : structure prediction and orientation

correspondence: indrani Karunasagar Department of Fishery Microbiology, college of Fisheries, Karnataka Veterinary, Animal and Fisheries sciences University, Mangalore 575 002, india Tel +91 824 2246384 Fax +91 824 2246384 email karuna8sagar@yahoo.com; mircen@sancharnet.in Abstract: The marine organism Vibrio vulnificus causes seafood-borne infection and is a major cause of human mortality. Secretin, a major component of the type III secretion system (TTSS) virulence machinery, forms oligomeric rings in the outer membrane of many Gram-negative organisms. The secretin ring-shaped complexes possess pore-forming activity. The pores function as channels for transport of macromolecules across the complex. However, the TTSS secretin family has not been studied in V. vulnificus. The secretin of TTSS of V. vulnificus was identified and predicted to be homologous to secretin of Gram-negative organisms like Yersinia and Escherichia coli. It contained an amino-terminal signal peptide region for processing by the sec machinery. The homology model of secretin of V. vulnificus possessed the E. coli periplasmic domain specific to secretin of TTSS. Buried pore-lining residues in the homology model were identified by bioinformatics tools. Thus, secretin of V. vulnificus may function as channels to allow transport of molecules. The optimized pore axis with the biggest and longest cavity through the channel was detected which generated a guide to the orientation of secretin in V. vulnificus. Thus, the secretin of V. vulnificus has a conserved C-terminal domain enclosing a pore and a nonconserved lipolytic motif which may be involved in adherence to the chitinous surface.