title: Immune responses to an attenuated West Nile virus NS4B-P38G mutant strain.
abstract: The nonstructural (NS) proteins of West Nile virus (WNV) have been associated with participation in evasion of host innate immune defenses. In the present study, we characterized immune response to an attenuated WNV strain, which has a P38G substitution in the NS4B protein. The WNV NS4B-P38G mutant induced a lower level of viremia and no lethality in C57BL/6 (B6) mice following a systemic infection. Interestingly, there were higher type 1 IFNs and IL-1β responses compared to mice infected by wild-type WNV. NS4B-P38G mutant-infected mice also showed stronger effector and memory T cell responses. WNV specific antibody responses were not different between mice infected with these two viruses. As a consequence, all mice were protected from a secondary infection with a lethal dose of wild-type WNV following a primary infection with NS4B-P38G mutant. Moreover, NS4B-P38G mutant infection in cultured bone-marrow derived dendritic cells (DCs) were shown to have a reduced replication rate, but a higher level of innate cytokine production than wild-type WNV, some of which were dependent on Myd88 signaling. In conclusion, the NS4B-P38G mutant strain induces higher protective innate and adaptive immune response in mice, which results in a lower viremia and no lethality in either primary or secondary infection, suggesting a high potential as an attenuating mutation in a vaccine candidate.
authors.affiliation: Department of Microbiology & Immunology, The University of Texas Medical Branch, Galveston, TX 77555, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Welte
authors.forename: Guorui
authors.initials: G
authors.lastname: Xie
authors.forename: Jason A
authors.initials: JA
authors.lastname: Wicker
authors.forename: Melissa C
authors.initials: MC
authors.lastname: Whiteman
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.forename: Aparna
authors.initials: A
authors.lastname: Rachamallu
authors.forename: Alan
authors.initials: A
authors.lastname: Barrett
authors.forename: Tian
authors.initials: T
authors.lastname: Wang
mesh_terms: D019943:Amino Acid Substitution / Q000235:genetics*; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D016207:Cytokines / Q000378:metabolism; D004195:Disease Models, Animal; D007156:Immunologic Memory; D051379:Mice; D008810:Mice, Inbred C57BL; D020125:Mutation, Missense; D012376:Rodent Diseases / Q000517:prevention & control; D016019:Survival Analysis; D013601:T-Lymphocytes / Q000276:immunology; D014613:Vaccines, Attenuated / Q000009:adverse effects / Q000235:genetics / Q000276:immunology; D017361:Viral Nonstructural Proteins / Q000235:genetics*; D014766:Viremia; D014901:West Nile Fever / Q000401:mortality / Q000473:pathology / Q000517:prevention & control* / Q000821:virology; D053060:West Nile Virus Vaccines / Q000009:adverse effects* / Q000235:genetics / Q000276:immunology*; D014902:West Nile virus / Q000235:genetics / Q000472:pathogenicity*
chemical_list: D000914:Antibodies, Viral; D016207:Cytokines; C080107:NS4B protein, flavivirus; D014613:Vaccines, Attenuated; D017361:Viral Nonstructural Proteins; D053060:West Nile Virus Vaccines