bioRxiv preprint doi: https://doi.org/10.1101/2020.06.26.174151; this version posted June 26, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. 1 Nfkbid is required for immunity and antibody responses to Toxoplasma gondii 2 3 Scott P Souza1, Samantha D Splitt1, Julia A Alvarez1, Safuwra Wizzard1, Jessica N Wilson1, 4 Zheng Luo2, Nicole Baumgarth2, Kirk DC Jensen1# 5 6 1School of Natural Sciences, University of California, Merced 7 2Center for Immunology & Infectious Diseases, and Department of Pathology, Microbiology and 8 Immunology, University of California, Davis 9 10 # Correspondence: Kirk D.C. Jensen,
[email protected] 11 12 ABSTRACT 13 No fully protective vaccine has yet been developed for any human parasite. We previously 14 reported that South American strains of Toxoplasma gondii are adept at immune evasion and 15 cause lethal secondary infections in chronically infected mice. Here we report that unlike 16 susceptible C57BL/6J mice, A/J mice were highly resistant to secondary infection. Mapping 17 immunity loci that segregated within a recombinant inbred panel of mice we identified Nfkbid, a 18 nuclear regulator of NF-κB that is required for B-1 cell development. Nfkbid-null mice (bumble) 19 were susceptible to secondary, but not primary infections and failed to generate parasite- 20 specific IgM and lacked robust parasite-specific IgG. In resistant mice, B-1 cells bore evidence 21 for Nfkbid-dependent responses, including Ighg expression, and were partially responsible for 22 the immunity defect in bumble mice.