title: A natural genetic variant of granzyme B confers lethality to a common viral infection.
abstract: Many immune response genes are highly polymorphic, consistent with the selective pressure imposed by pathogens over evolutionary time, and the need to balance infection control with the risk of auto-immunity. Epidemiological and genomic studies have identified many genetic variants that confer susceptibility or resistance to pathogenic micro-organisms. While extensive polymorphism has been reported for the granzyme B (GzmB) gene, its relevance to pathogen immunity is unexplored. Here, we describe the biochemical and cytotoxic functions of a common allele of GzmB (GzmBW) common in wild mouse. While retaining 'Asp-ase' activity, GzmBW has substrate preferences that differ considerably from GzmBP, which is common to all inbred strains. In vitro, GzmBW preferentially cleaves recombinant Bid, whereas GzmBP activates pro-caspases directly. Recombinant GzmBW and GzmBP induced equivalent apoptosis of uninfected targets cells when delivered with perforin in vitro. Nonetheless, mice homozygous for GzmBW were unable to control murine cytomegalovirus (MCMV) infection, and succumbed as a result of excessive liver damage. Although similar numbers of anti-viral CD8 T cells were generated in both mouse strains, GzmBW-expressing CD8 T cells isolated from infected mice were unable to kill MCMV-infected targets in vitro. Our results suggest that known virally-encoded inhibitors of the intrinsic (mitochondrial) apoptotic pathway account for the increased susceptibility of GzmBW mice to MCMV. We conclude that different natural variants of GzmB have a profound impact on the immune response to a common and authentic viral pathogen.
authors.affiliation: Immunology and Virology Program, Centre for Ophthalmology and Visual Science, The University of Western Australia, Crawley, Western Australia, Australia; Centre for Experimental Immunology, Lions Eye Institute, Nedlands, Western Australia, Australia.
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Andoniou
authors.affiliation: Cancer Immunology Program, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia; Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Vivien R
authors.initials: VR
authors.lastname: Sutton
authors.affiliation: Immunology and Virology Program, Centre for Ophthalmology and Visual Science, The University of Western Australia, Crawley, Western Australia, Australia; Centre for Experimental Immunology, Lions Eye Institute, Nedlands, Western Australia, Australia.
authors.forename: Matthew E
authors.initials: ME
authors.lastname: Wikstrom
authors.affiliation: Immunology and Virology Program, Centre for Ophthalmology and Visual Science, The University of Western Australia, Crawley, Western Australia, Australia; Centre for Experimental Immunology, Lions Eye Institute, Nedlands, Western Australia, Australia.
authors.forename: Peter
authors.initials: P
authors.lastname: Fleming
authors.affiliation: Cancer Immunology Program, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia; Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Kevin Y T
authors.initials: KY
authors.lastname: Thia
authors.affiliation: Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Monash University, Clayton, Victoria, Australia.
authors.forename: Antony Y
authors.initials: AY
authors.lastname: Matthews
authors.affiliation: Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Monash University, Clayton, Victoria, Australia.
authors.forename: Dion
authors.initials: D
authors.lastname: Kaiserman
authors.affiliation: Immunology and Virology Program, Centre for Ophthalmology and Visual Science, The University of Western Australia, Crawley, Western Australia, Australia; Centre for Experimental Immunology, Lions Eye Institute, Nedlands, Western Australia, Australia.
authors.forename: Iona S
authors.initials: IS
authors.lastname: Schuster
authors.affiliation: Immunology and Virology Program, Centre for Ophthalmology and Visual Science, The University of Western Australia, Crawley, Western Australia, Australia; Centre for Experimental Immunology, Lions Eye Institute, Nedlands, Western Australia, Australia.
authors.forename: Jerome D
authors.initials: JD
authors.lastname: Coudert
authors.affiliation: Infection and Immunity Group, Department of Immunology, The John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital Territory, Australia.
authors.forename: Preethi
authors.initials: P
authors.lastname: Eldi
authors.affiliation: Infection and Immunity Group, Department of Immunology, The John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital Territory, Australia.
authors.forename: Geeta
authors.initials: G
authors.lastname: Chaudhri
authors.affiliation: Infection and Immunity Group, Department of Immunology, The John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital Territory, Australia.
authors.forename: Gunasegaran
authors.initials: G
authors.lastname: Karupiah
authors.affiliation: Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Monash University, Clayton, Victoria, Australia.
authors.forename: Phillip I
authors.initials: PI
authors.lastname: Bird
authors.affiliation: Cancer Immunology Program, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia; Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Trapani
authors.affiliation: Immunology and Virology Program, Centre for Ophthalmology and Visual Science, The University of Western Australia, Crawley, Western Australia, Australia; Centre for Experimental Immunology, Lions Eye Institute, Nedlands, Western Australia, Australia.
authors.forename: Mariapia A
authors.initials: MA
authors.lastname: Degli-Esposti
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis; D018414:CD8-Positive T-Lymphocytes / Q000473:pathology / Q000821:virology; D020169:Caspases / Q000378:metabolism; D004195:Disease Models, Animal; D014644:Genetic Variation / Q000235:genetics*; D053804:Granzymes / Q000032:analysis / Q000172:deficiency / Q000235:genetics*; D006566:Herpesviridae Infections / Q000276:immunology* / Q000401:mortality* / Q000473:pathology; D007113:Immunity, Innate / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D018146:Muromegalovirus / Q000276:immunology*; D014777:Virus Diseases / Q000276:immunology* / Q000401:mortality* / Q000473:pathology
chemical_list: D053804:Granzymes; D020169:Caspases