Immunization of Macaca mulatta with aroA attenuated Salmonella typhimurium expressing the SIVp27 antigen

Area of Science:

• * Immunology
• * Microbiology
• * Vaccinology

Background:

• * Attenuated bacteria can elicit immune responses to foreign antigens.
• * Salmonella typhimurium is a potential vector for delivering antigens.
• * Simian immunodeficiency virus (SIV) p27 capsid protein is a target for vaccine development.

Purpose of the Study:

• * To evaluate the safety and stability of attenuated Salmonella typhimurium expressing SIV p27 in rhesus macaques.
• * To assess the antigen delivery capacity of the recombinant bacteria.

Main Methods:

• * Juvenile rhesus macaques were inoculated with varying doses of aroA attenuated S. typhimurium expressing SIV p27.
• * Bacterial shedding, clinical signs, and in vivo stability of the bacteria and expression cassette were monitored.
• * In vitro analysis quantified the amount of p27 delivered per dose.

Main Results:

• * The bacterial infection was self-limiting with no clinical signs observed.
• * Salmonella was shed for approximately five days and retained its attenuating mutation and SIVp27 expression cassette.
• * A minimum of 7.2 microg of p27 was delivered per oral dose.

Conclusions:

• * Oral administration of attenuated S. typhimurium expressing SIV p27 is safe in rhesus macaques.
• * The recombinant bacteria are genetically stable in vivo.
• * This approach shows potential for oral delivery of SIV antigens for vaccine strategies.