CHRONIC STAPHYLOCOCCAL MASTITIS: ERADICATION OF PATHOGENS THAT RESIDE INTRACELLULARLY
Animal Biosciences and Biotechnology Laboratory
2013 Annual Report
1a.Objectives (from AD-416):
Test the ability of a fusion protein [lysostaphin fusion to the HIV TAT protein transduction domain] to cure chronic mastitis in cattle.
1b.Approach (from AD-416):
Field trial with chronically infected cows.
Significant progress was made on Component 2: Understanding, Improving, and Effectively Using Animal Genetic and Genomic Resources. Progress on this project focuses on Problem Statement 2E: Improved Techniques for Genetic Modification and Genetic Engineering of Food Animals. There has been significant advancement on this project to help cure chronic mastitis, an infection of the mammary gland. Mastitis is a costly disease for dairy farming in the United States with over $2 billion in losses to the industry annually. Progress has been made in developing a system for analyzing the eradication of bacterial pathogens residing within cultured bovine mammary gland cells. Antimicrobial enzymes harboring three unique activities that degrade the bacterial cell wall in three unique regions have been created and were fused to 11 different protein fragments (protein transduction domains) that facilitate transport of the antimicrobial enzymes across the cell wall. These triple-acting enzyme fusions were tested and optimal fusions for eradicating pathogens from within mammary cells in culture were identified. Due to solubility problems, the optimal triple-acting enzyme was not able to be produced in sufficiently high amounts and concentrations for injection into the teat canal of cattle infected with the mastitis causing bacteria Staphylococcus aureus. Thus, a suboptimal triple-acting enzyme was introduced into the infected glands; however it was inadequate for eradicating chronic bacterial infections. This work has helped to identify solubility, activity and concentration requirements when creating antimicrobials to cure chronic multi-drug resistant pathogens and other drug resistant Staphylococcus aureus infections, such as osteomyelitis (bone infections) in humans.