title: Pasteurella pneumotropica evades the human complement system by acquisition of the complement regulators factor H and C4BP.
abstract: Pasteurella pneumotropica is an opportunist Gram negative bacterium responsible for rodent pasteurellosis that affects upper respiratory, reproductive and digestive tracts of mammals. In animal care facilities the presence of P. pneumotropica causes severe to lethal infection in immunodeficient mice, being also a potential source for human contamination. Indeed, occupational exposure is one of the main causes of human infection by P. pneumotropica. The clinical presentation of the disease includes subcutaneous abscesses, respiratory tract colonization and systemic infections. Given the ability of P. pneumotropica to fully disseminate in the organism, it is quite relevant to study the role of the complement system to control the infection as well as the possible evasion mechanisms involved in bacterial survival. Here, we show for the first time that P. pneumotropica is able to survive the bactericidal activity of the human complement system. We observed that host regulatory complement C4BP and Factor H bind to the surface of P. pneumotropica, controlling the activation pathways regulating the formation and maintenance of C3-convertases. These results show that P. pneumotropica has evolved mechanisms to evade the human complement system that may increase the efficiency by which this pathogen is able to gain access to and colonize inner tissues where it may cause severe infections.
authors.affiliation: Departamento de Microbiología e Inmunología, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Mexico City, Mexico.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Sahagún-Ruiz
authors.affiliation: Departamento de Imunologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Adriana Patricia
authors.initials: AP
authors.lastname: Granados Martinez
authors.affiliation: Departamento de Imunologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Leandro Carvalho Dantas
authors.initials: LC
authors.lastname: Breda
authors.affiliation: Departamento de Imunologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Tatiana Rodrigues
authors.initials: TR
authors.lastname: Fraga
authors.affiliation: Departamento de Imunologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Mónica Marcela
authors.initials: MM
authors.lastname: Castiblanco Valencia
authors.affiliation: Laboratório de Bacteriologia, Instituto Butantan, São Paulo, Brazil.
authors.forename: Angela Silva
authors.initials: AS
authors.lastname: Barbosa
authors.affiliation: Departamento de Imunologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Lourdes
authors.initials: L
authors.lastname: Isaac
mesh_terms: D050577:Complement C3-C5 Convertases / Q000378:metabolism; D050716:Complement C4b-Binding Protein / Q000276:immunology*; D017242:Complement Factor H / Q000276:immunology*; D006801:Humans; D044142:Pasteurella pneumotropica / Q000276:immunology*
chemical_list: D050716:Complement C4b-Binding Protein; D017242:Complement Factor H; D050577:Complement C3-C5 Convertases