Nabi Biopharmaceuticals announced that the U.S. Patent and Trademark Office has issued U.S. Patent No. 6,537,559 entitled "Staphylococcus aureus antigen-containing whole cell vaccine." This patent covers the composition of a S. aureus vaccine, the method of vaccine preparation, immunotherapy and its use as a therapeutic or prophylactic agent to protect animals against infection. The Staphylococcus aureus vaccine, as detailed in the patent, specifically covers the incorporation of whole cells, cell lysate, cell derivatives and antigens obtained from the three significant bacterial strains (types 5, 8, and 336) that comprise nearly all of the S. aureus isolates found in infected animals in North America and Europe.

The Gram-positive bacterium, Staphylococcus aureus is the most frequent cause of mastitis, one of the most common and costly diseases affecting dairy, and beef cattle. This disease results in significantly higher costs for producers of dairy and beef products due to discarded milk, decreased productivity, treatment expense, and the inability of infected cows to suckle calves. The U.S. National Mastitis Council estimates that the annual losses to the dairy industry amount to $1.8 to $2 billion dollars. Losses due to discarded milk alone are thought to amount to $1 billion.

In a preliminary study, Nabi Biopharmaceuticals has demonstrated the ability of the trivalent vaccine to clear chronic Staphylococcus aureus intramammary infections in dairy cows. If shown to be efficacious in field trials, this vaccine should help to limit the spread of the disease within herds and alleviate the usage of antibiotics. David Gury, chairman and chief executive officer said, "This newest patent adds further strength to our portfolio of potential products aimed at preventing and treating serious Staphylococcus aureus infections. We intend to out-license this technology to a company with a significant animal health product portfolio to maximize the potential of this veterinary vaccine."

The technology represented in this patent is an extension of the StaphVAXs (S. aureus polysaccharide conjugate vaccine) technology being developed by Nabi Biopharmaceuticals to prevent and treat staphylococcal infections in humans. The company is currently preparing to initiate a second Phase III trial of StaphVAX for the prevention of S. aureus bacteremia in humans. The first Phase III trial of StaphVAX showed a 57% decrease in S. aureus bacteremia in end-stage renal disease patients over a 10-month period. A further booster clinical trial demonstrated increased concentration of serum antibodies against S. aureus, when StaphVAX was re-administered an average of 960 days after the first dose.