Antigen for Vaccines Against Rickettsial Diseases Affecting Humans and Animals

Technology #15717

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Anthony F. Barbet
Francy L. Crosby
Managed By
John Byatt
Assistant Director 352-392-8929

Recombinant Protein Vaccine Protects Against Pathogenic Bacteria

This recombinant protein antigen will potentially lead to improved and more effective vaccines against a number of Rickettsial diseases and also may be useful for immunization against a number of other gram negative bacteria. Rickettsial diseases – such as R. typhi, R. prowazekii, R. rickettsii and R. conorii – have wide global incidence and pose potential biological threats. These diseases are generally incapacitating and sometimes life-threatening, because they are difficult to diagnose since symptoms of infection – fever, headache, myalgia, nausea, vomiting – could indicate any number of diseases. Epidemic typhus, caused by Rickettsia typhi, and Rocky Mountain spotted fever, caused by Rickettsia rickettsii, can reach up to 60 percent fatalities without effective antibiotic treatment. Available vaccine options include either a killed Rickettsial bacterium that offers incomplete protection or a live attenuated bacterium that initially offers strong immunity but may revert to virulence. Researchers at the University of Florida have identified a new antigen that can be used to create an improved vaccine against Rickettsia as well as other gram negative bacteria harmful to humans, pets, and livestock. The vaccine is based on a recombinant protein found in type 4 secretion systems common in gram negative bacteria, making the antigen applicable to vaccines against a number of pathogenic bacteria including Anaplasma and Ehrlichia.


Vaccine against Rickettsial diseases and other gram negative bacteria


  • Species-specific variants of the VirB10 protein found in type 4 secretion systems, can be used to generate vaccines for multiple different bacterial species


Type 4 secretion systems (T4SS) are used by many gram negative bacteria to secrete DNA and proteins that can increase or decrease enzyme activity, gene expression, or cell signaling across cell membranes. The T4SS comprises a complex of 12 proteins; one of which is VirB10. Recombinant VirB10, when used as a vaccine in mice, generated protection against infection by Anaplasma phagocytophilum, thus demonstrating that VirB10 can elicit a robust and protective immune response and potentially is the basis for improved vaccines against a number of pathogenic bacteria that have T4SS (e.g., Anaplasma sp., Ehrlichia sp., and Rickettsial sp.) and that can infect both people and animals.