title: Complement activation is required for induction of a protective antibody response against West Nile virus infection.
abstract: Infection with West Nile virus (WNV) causes a severe infection of the central nervous system (CNS) with higher levels of morbidity and mortality in the elderly and the immunocompromised. Experiments with mice have begun to define how the innate and adaptive immune responses function to limit infection. Here, we demonstrate that the complement system, a major component of innate immunity, controls WNV infection in vitro primarily in an antibody-dependent manner by neutralizing virus particles in solution and lysing WNV-infected cells. More decisively, mice that genetically lack the third component of complement or complement receptor 1 (CR1) and CR2 developed increased CNS virus burdens and were vulnerable to lethal infection at a low dose of WNV. Both C3-deficient and CR1- and CR2-deficient mice also had significant deficits in their humoral responses after infection with markedly reduced levels of specific anti-WNV immunoglobulin M (IgM) and IgG. Overall, these results suggest that complement controls WNV infection, in part through its ability to induce a protective antibody response.
authors.affiliation: Department of Medicine, Molecular Microbiology, and Pathology & Immunology, Washington University School of Medicine, 660 South Euclid Ave., Box 8051, St. Louis, MO 63110, USA.
authors.forename: Erin
authors.initials: E
authors.lastname: Mehlhop
authors.forename: Kevin
authors.initials: K
authors.lastname: Whitby
authors.forename: Theodore
authors.initials: T
authors.lastname: Oliphant
authors.forename: Anantha
authors.initials: A
authors.lastname: Marri
authors.forename: Michael
authors.initials: M
authors.lastname: Engle
authors.forename: Michael S
authors.initials: MS
authors.lastname: Diamond
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood* / Q000276:immunology; D001921:Brain / Q000276:immunology / Q000821:virology; D002460:Cell Line; D003167:Complement Activation; D003176:Complement C3 / Q000235:genetics; D006224:Cricetinae; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D007075:Immunoglobulin M / Q000097:blood / Q000276:immunology; D051379:Mice; D009500:Neutralization Tests; D011951:Receptors, Complement / Q000235:genetics; D014901:West Nile Fever / Q000276:immunology* / Q000821:virology; D014902:West Nile virus / Q000276:immunology* / Q000472:pathogenicity*
chemical_list: D000914:Antibodies, Viral; D003176:Complement C3; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D011951:Receptors, Complement