Specific Cryptosporidium antigens associate with reinfection immunity and protection from cryptosporidiosis
Carol A. Gilchrist, … , Rashidul Haque, William A. Petri Jr.
Carol A. Gilchrist, … , Rashidul Haque, William A. Petri Jr.
Published June 22, 2023
Citation Information: J Clin Invest. 2023;133(16):e166814. https://doi.org/10.1172/JCI166814.
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Research Article Immunology Infectious disease

Specific Cryptosporidium antigens associate with reinfection immunity and protection from cryptosporidiosis

Abstract

There is no vaccine to protect from cryptosporidiosis, a leading cause of diarrhea in infants in low- and middle-income countries. Here, we comprehensively identified parasite antigens associated with protection from reinfection. A Cryptosporidium protein microarray was constructed by in vitro transcription and translation of 1,761 C. parvum, C. hominis, or C. meleagridis antigens, including proteins with a signal peptide and/or a transmembrane domain. Plasma IgG and/or IgA from Bangladeshi children longitudinally followed for cryptosporidiosis from birth to 3 years of age allowed for identification of 233 seroreactive proteins. Seven of these were associated with protection from reinfection. These included Cp23, Cp17, Gp900, and 4 additional antigens — CpSMP1, CpMuc8, CpCorA and CpCCDC1. Infection in the first year of life, however, often resulted in no detectable antigen-specific antibody response, and antibody responses, when detected, were specific to the infecting parasite genotype and decayed in the months after infection. In conclusion, humoral immune responses against specific parasite antigens were associated with acquired immunity. While antibody decay over time and parasite genotype-specificity may limit natural immunity, this work serves as a foundation for antigen selection for vaccine design.

Authors

Carol A. Gilchrist, Joseph J. Campo, Jozelyn V. Pablo, Jennie Z. Ma, Andy Teng, Amit Oberai, Adam D. Shandling, Masud Alam, Mamun Kabir, A.S.G. Faruque, Rashidul Haque, William A. Petri Jr.

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Figure 3

Antibody responses waned with time after a Cryptosporidium infection.

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Antibody responses waned with time after a Cryptosporidium infection. (A...
(A) The t-SNE plot identified a subset of children with a similar antibody profile. Each point corresponds to the immune profile of a child. Gray squares indicate children where no previous Cryptosporidium infections were identified by qPCR in clinical or surveillance stool samples (“qPCR–”), and orange circles represent children that had previous infections detected by qPCR (“qPCR+”), with the intensity of the overlaid color indicating the days since the last Cryptosporidium qPCR+ stool sample was identified. A group of infants had similar antibody profiles and a high density of recent infections (R1). (B) The split violin plot of antibody signals against the 100 most-reactive antigens (Y-axis) for each isotype (X-axis) shows the responses of children within the R1 region of the t-SNE plot compared with the remainder of the samples in R2. The median and quartile values are shown as horizontal lines in each split violin. (C) The split violin plot shows the same comparison as (B) using the antibody breadth (count of seropositive responses) among the 100 most-reactive antigens. P values above each split violin were calculated using linear mixed effects regression (LMER) and Wilcoxon’s rank sum tests for (B and C), respectively. (D) Antibody breadth among the 100 most-reactive antigens for each isotype is shown on the Y-axis after log10 transformation with the interval (days) between the last Cryptosporidium qPCR+ diagnostic assay and the time of antibody measurement shown on the X-axis. Linear regression P values and R2 values are shown for IgG and IgA, as well as a line and confidence intervals (colored bands; pink for IgA and green for IgG) fit to each. (E and F) PLS-DA is shown for IgA and IgG responses respectively. Each point corresponds to the immune profile of a child. The purple circles indicate the antibody response obtained from plasma that was collected from children where none of the stool samples (diarrheal or surveillance) collected during the first year of life, prior to the plasma sampling time point, were ever qPCR positive for Cryptosporidium parasites (“Yr0-1 qPCR–”). Green triangles indicate that the child had a verified Cryptosporidium subclinical or symptomatic infection (“Yr-0-1 qPCR+”). The percentage of the variation in the child’s antibody profile accounted for by each axis is indicated.