Metabolic engineering of Salmonella vaccine bacteria to boost human Vγ2Vδ2 T cell immunity.

Abstract

Human Vγ2Vδ2 T cells monitor isoprenoid metabolism by recognizing foreign (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate (HMBPP), a metabolite in the 2-C-methyl-D-erythritol-4-phosphate pathway used by most eubacteria and apicomplexan parasites, and self isopentenyl pyrophosphate, a metabolite in the mevalonate pathway used by humans. Whereas microbial infections elicit prolonged expansion of memory Vγ2Vδ2 T cells, immunization with prenyl pyrophosphates or aminobisphosphonates elicit short-term Vγ2Vδ2 expansion with rapid anergy and deletion upon subsequent immunizations. We hypothesized that a live, attenuated bacterial vaccine that overproduces HMBPP would elicit long-lasting Vγ2Vδ2 T cell immunity by mimicking a natural infection. Therefore, we metabolically engineered the avirulent aroA(-) Salmonella enterica serovar Typhimurium SL7207 strain by deleting the gene for LytB (the downstream enzyme from HMBPP) and functionally complementing for this loss with genes encoding mevalonate pathway enzymes. LytB(-) Salmonella SL7207 had high HMBPP levels, infected human cells as efficiently as did the wild-type bacteria, and stimulated large ex vivo expansions of Vγ2Vδ2 T cells from human donors. Importantly, vaccination of a rhesus monkey with live lytB(-) Salmonella SL7207 stimulated a prolonged expansion of Vγ2Vδ2 T cells without significant side effects or anergy induction. These studies provide proof-of-principle that metabolic engineering can be used to derive live bacterial vaccines that boost Vγ2Vδ2 T cell immunity. Similar engineering of metabolic pathways to produce lipid Ags or B vitamin metabolite Ags could be used to derive live bacterial vaccine for other unconventional T cells that recognize nonpeptide Ags.

• Authors: Grefachew Workalemahu, Hong Wang, Kia-Joo Puan, Mohanad H Nada, Tomohisa Kuzuyama, Bradley D Jones, Chenggang Jin, Craig T Morita
• Journal: Journal of immunology (Baltimore, Md. : 1950) (J Immunol) Vol. 193 Issue 2 Pg. 708-21 (Jul 15 2014) ISSN: 1550-6606 [Electronic] United States
• PMID: 24943221 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.)

Chemical References

• 4-hydroxy-3-methyl-2-butenyl diphosphate
• Bacterial Proteins
• Organophosphates
• Receptors, Antigen, T-Cell, gamma-delta
• Salmonella Vaccines
• Mevalonic Acid

Topics

• Animals
• Bacterial Proteins (genetics, immunology, metabolism)
• Cell Proliferation
• Cells, Cultured
• Gene Deletion
• Humans
• Immunization
• Lymphocyte Activation (immunology)
• Macaca mulatta (immunology)
• Metabolic Engineering (methods)
• Metabolic Networks and Pathways (genetics, immunology)
• Mevalonic Acid (metabolism)
• Organophosphates (metabolism)
• Receptors, Antigen, T-Cell, gamma-delta (immunology, metabolism)
• Salmonella Vaccines (immunology)
• Salmonella typhimurium (genetics, immunology, metabolism)
• T-Lymphocytes (immunology, metabolism)