A new vaccine based on siderophore receptor and porin (SRP) technology is showing considerable promise in reducing klebsiella mastitis in dairy cows, based on data from an Iowa State University trial shared at the recent Academy of Veterinary Consultants spring conference in Dallas, Texas.

Dr. Patrick Gorden, clinical professor of veterinary diagnostic and production animal medicine at Iowa State, said the Klebsiella pneumoniae bacterial extract vaccine (Kleb-SRP) reduced the prevalence of klebsiella mastitis by 71% in the vaccinated half of the herd. The Iowa State dairy herd was chosen for the trial due to an ongoing klebsiella mastitis problem, which had persisted despite using multiple doses of Escherichia coli core antigen vaccine annually.

In addition to prevalence reduction, the Kleb-SRP vaccine also reduced mastitis incidence -- which accounts for recurring infections in a single dairy cow -- by 76%. Milk production increased in Kleb-SRP vaccinated cows by 2 lb. per cow per day, and somatic cell count was reduced by 42% compared to the non-vaccinated half of the herd.

"Production losses from klebsiella mastitis, as well as deaths or culling that result from severe mastitis infections, are a significant challenge for the dairy industry," Gorden said. "A different approach to controlling klebsiella mastitis is sorely needed."

The Kleb-SRP vaccine is currently offered as an autogenous product by AgriLabs, in partnership with Epitopix. AgriLabs is working to license the vaccine with the U.S. Department of Agriculture, and the Iowa State study is part of the efficacy trial work associated with the licensing process.

Sean O'Hare, executive vice president of AgriLabs, said results from the Iowa State trial align with field results with the autogenous product. "Klebsiella mastitis is a frustrating production challenge for dairy producers, and we're seeing considerable potential for the Kleb-SRP vaccine to reduce production losses, deaths and culls," he said.

The vaccine technology is fundamentally different from other options because it utilizes SRP technology. Disease-causing bacteria such as klebsiella require iron for growth and survival. When vaccinated with SRP, the cow's immune system is stimulated to make antibodies against the targeted siderophore receptors and porins, located in the outer wall of the bacteria. SRP vaccine-induced antibodies bind and block the transfer of iron and nutrients through bacterial cell wall pores, starving bacteria of needed nutrients, specifically iron.