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United States Department of Agriculture

Agricultural Research Service

Research Project: EVALUATION OF GENETICALLY ENGINEERED CATTLE AND REFINING TECHNIQUES FOR PRODUCING THEM

Location: Animal Biosciences and Biotechnology Laboratory

Title: A Novel Use of a Bacteriophage Lysin, PlyC, as a Disinfectant against Streptococcus equi

Authors
item Donovan, David
item Hoopes, J - UNIV OF MD
item Stark, Caren - UNIV OF MD
item Kim, Han - UNIV OF MD
item Sussman, Daniel - COLUMBIA MD
item Nelson, Daniel - UNIV OF MD

Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 24, 2008
Publication Date: March 1, 2009
Citation: Hoopes, J.T., Stark, C.J., Kim, H.A., Sussman, D.J., Donovan, D.M., Nelson, D.C. 2009. A Novel Use of a Bacteriophage Lysin, PlyC, as a Disinfectant against Streptococcus equi. Applied and Environmental Microbiology. 75(5):1388-94.

Interpretive Summary: Interpretive Summary: C. Problem— Streptococcus equi is the causative agent of a purulent infection in horses known as equine strangles and is transmitted through shedding of live bacteria from nasal secretions and abscess drainage. Disease prevention methods include quarantine of infected animals and disinfection of equipment, stalls, and the environment. While currently approved disinfectants are effective against S. equi, there are issues of inactivation by detergents, hard water, or organic load, possible damage to equipment, and toxicity concerns for horses. Vaccines also exist, but are of poor quality, low efficacy, and include the risk of conferring the disease on the animal. A disinfectant that is less caustic and less damaging to materials associated with horse care and maintenance is essential. C. Accomplishment— Here we investigate the ability of one lysin, PlyC, to be used as a narrow-spectrum disinfectant against S. equi. This enzyme was active against >20 clinical isolates of S. equi, including both subspecies equi and zooepidemicus. Significantly, PlyC was 1000x more active on a w/v basis than Virkon-S®, a common disinfecting agent, at killing 108 cfu/ml S. equi in 30 min. Results indicate that soluble PlyC when aerosolized can eradicate or significantly reduce (>1000X) the S. equi load on a variety of materials found on common stall and horse-related equipment. Additionally it was shown to retain full activity under conditions that mimic a horse barn, i.e. in the presence of non-ionic detergents, EDTA, hard water, and a 10% organic load. C. Contribution of Accomplishment to Solving the Problem— We feel that we have identified a protein disinfectant that is active when solubilized following lyophilization, is more effective against S. equi than conventional disinfectants, is less damaging to horse related equipment and might eventually be used to treat the horses directly as an antimicrobial for equine strangles.

Technical Abstract: Streptococcus equi is the causative agent of a purulent infection in horses known as equine strangles and is transmitted through shedding of live bacteria from nasal secretions and abscess drainage. There are no accepted cures for equine strangles with conventional antibiotics being only partially effective. Disease prevention methods are limited to quarantine of infected animals, disinfection of equipment and stalls, and a low efficacy vaccine, for which the documentation warns of the risk of conferring the disease on an otherwise healthy animal. While approved disinfectants are effective against S. equi, there are concerns of inactivation by detergents, hard water, or organic load, possible damage to equipment, and toxicity toward the horses. Bacteriophage lysins (cell wall hydrolases) have gained interest as therapeutic enzymes for their ability to cause lysis in susceptible Gram-positive organisms. Here we investigate the ability of one lysin, PlyC, to be used as a narrow-spectrum disinfectant against S. equi. This enzyme was active against >20 clinical isolates of S. equi, including both subspecies equi and zooepidemicus. Significantly, PlyC was 1000x more active on a w/v basis than Virkon-S®, a common disinfecting agent, at killing 108 cfu/ml S. equi in 30 min. PlyC was subjected to a standard battery of tests published by the Association of Official Analytical Chemists, including the Use-Dilution Methods for Testing Disinfectants and the Germicidal Spray Products Test. It is known that PlyC retains near full activity when resuspended following lyophilization. Results indicate that soluble PlyC when aerosolized can eradicate or significantly reduce (>1000X) the S. equi load on a variety of materials found on common stall and horse-related equipment. Additionally it was shown to retain full activity under conditions that mimic a horse barn, i.e. in the presence of non-ionic detergents, EDTA, hard water, and a 10% organic load. We propose PlyC as the first protein-based, narrow-spectrum disinfectant against S. equi.

Last Modified: 9/2/2014
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