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United States Department of Agriculture

Agricultural Research Service

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Gast, Richard K
Supervisory Microbiologist
Richard.Gast@ars.usda.gov
(706) 546-3445
South Atlantic Area
950 College Station Road
Athens GA 30605

Mission:
The mission of the Egg Safety and Quality Research Unit is to protect both the health of consumers and the marketability of eggs by conducting research to develop improved technologies for egg production and processing that reduce or eliminate microorganisms that can transmit disease to humans or cause spoilage. Among the specific objectives of this research are determining how microbial pathogens infect poultry and cause egg contamination, understanding how poultry production practices can influence such infections, developing effective methods for preventing infection of egg-laying poultry by pathogens and for testing to detect infected flocks and contaminated eggs, and improving egg processing practices to reduce microbial contamination while enhancing egg quality.

                                                             Intergenic Sequence Ribotype

Serotyping of Salmonella enterica species is the basis of national and international surveillance and communications.  It facilitates determining asscociations between the pathogen and sources and it gives some guidance in regards to preventing transmission.

The historic method used to serotype S. enterica is the antibody-based Kauffman-White (KW) scheme.  Postive results generate an antigenic formula based on structural details of the H-antigen of flagella and the O-antigen of lipopolysaccharide.

A major advantage of DNA analysis is that it is not impacted by variable expression of cell-surface antigens as are antibody-based agglutination assays like the KW scheme.  Major obstacles to genome typing of S. enterica becoming broadly available include expense, the need for highly specialized equipment, and, in some cases, sophisticated bioinformatics.  A discrete region within the S. enterica  has been shown to differentiate closely related serotypes.  The region of interest spans from the end of a ribosomal gene, across a 5S gene and includes the last base pair preceding a tRNA aspU ribosmal gene neighboring dkgB (previously yafB ).  This DNA-based method for assigning serotype to S. enterica at comparatively low cost and with readily accessible laboratory equipment commonly used for culturing and conducting the polymerase chain reaction (PCR) is described here.  Click on the link above to get more information.

                                                             Intergenic Sequence Ribotype

Serotyping of Salmonella enterica species is the basis of national and international surveillance and communications.  It facilitates determining asscociations between the pathogen and sources and it gives some guidance in regards to preventing transmission.

The historic method used to serotype S. enterica is the antibody-based Kauffman-White (KW) scheme.  Postive results generate an antigenic formula based on structural details of the H-antigen of flagella and the O-antigen of lipopolysaccharide.

A major advantage of DNA analysis is that it is not impacted by variable expression of cell-surface antigens as are antibody-based agglutination assays like the KW scheme.  Major obstacles to genome typing of S. enterica becoming broadly available include expense, the need for highly specialized equipment, and, in some cases, sophisticated bioinformatics.  A discrete region within the S. enterica  has been shown to differentiate closely related serotypes.  The region of interest spans from the end of a ribosomal gene, across a 5S gene and includes the last base pair preceding a tRNA aspU ribosmal gene neighboring dkgB (previously yafB ).  This DNA-based method for assigning serotype to S. enterica at comparatively low cost and with readily accessible laboratory equipment commonly used for culturing and conducting the polymerase chain reaction (PCR) is described here.  Click on the link above to get more information.

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