TY - JOUR
T1 - Binding of the von willebrand factor a domain of capillary morphogenesis protein 2 to anthrax protective antigen vaccine reduces immunogenicity in mice
AU - de Oliveira, Fabiana Freire Mendes
AU - Mamillapalli, Sireesha
AU - Gonti, Srinivas
AU - Brey, Robert N.
AU - Li, Han
AU - Schiffer, Jarad
AU - Casadevall, Arturo
AU - Bann, James G.
N1 - Funding Information:
We thank Scheherazade Sadegh-Nasseri (JHU, School of Medicine) for her kind reading of and comments on the manuscript and Livia Liporagi Lopes (JHU, Bloomberg School of Public Health) for her assistance in preparing samples for the TNA assay at the CDC. This publication was made possible by grant P20 RR016475 from the National Center for Research Resources and grant P20GM103418 from the National Institute of General Medical Sciences, National Institutes of Health. F.F.M.O. was supported by scholarships from the Brazilian funding agencies CNPq and CAPES. The findings and conclusions in this article are those of the authors and do not necessarily represent the official position of the CDC.
Publisher Copyright:
© 2020.
PY - 2020/1/1
Y1 - 2020/1/1
N2 - Protective antigen (PA) is a component of anthrax toxin that can elicit toxin-neutralizing antibody responses. PA is also the major antigen in the current vaccine to prevent anthrax, but stability problems with recombinant proteins have complicated the development of new vaccines containing recombinant PA. The relationship between antigen physical stability and immunogenicity is poorly understood, but there are theoretical reasons to think that this parameter can affect immune responses. We investigated the immunogenicity of anthrax PA, in the presence and absence of the soluble von Willebrand factor A domain of the human form of receptor capillary morphogenesis protein 2 (sCMG2), to elicit antibodies to PA in BALB/c mice. Prior studies showed that sCMG2 stabilizes the 83-kDa PA structure to pH, chemical denaturants, temperature, and proteolysis and slows the hydrogen-deuterium exchange rate of histidine residues far from the binding interface. In contrast to a vaccine containing PA without adjuvant, we found that mice immunized with PA in stable complex with sCMG2 showed markedly reduced antibody responses to PA, including toxin-neutralizing antibodies and antibodies to domain 4, which correlated with fewer toxin-neutralizing antibodies. In contrast, mice immunized with PA in concert with a nonbinding mutant of sCMG2 (D50A) showed anti-PA antibody responses similar to those observed with PA alone. Our results suggest that addition of sCMG2 to a PA vaccine formulation is likely to result in a significantly diminished immune response, but we discuss the multitude of factors that could contribute to reduced immunogenicity.
AB - Protective antigen (PA) is a component of anthrax toxin that can elicit toxin-neutralizing antibody responses. PA is also the major antigen in the current vaccine to prevent anthrax, but stability problems with recombinant proteins have complicated the development of new vaccines containing recombinant PA. The relationship between antigen physical stability and immunogenicity is poorly understood, but there are theoretical reasons to think that this parameter can affect immune responses. We investigated the immunogenicity of anthrax PA, in the presence and absence of the soluble von Willebrand factor A domain of the human form of receptor capillary morphogenesis protein 2 (sCMG2), to elicit antibodies to PA in BALB/c mice. Prior studies showed that sCMG2 stabilizes the 83-kDa PA structure to pH, chemical denaturants, temperature, and proteolysis and slows the hydrogen-deuterium exchange rate of histidine residues far from the binding interface. In contrast to a vaccine containing PA without adjuvant, we found that mice immunized with PA in stable complex with sCMG2 showed markedly reduced antibody responses to PA, including toxin-neutralizing antibodies and antibodies to domain 4, which correlated with fewer toxin-neutralizing antibodies. In contrast, mice immunized with PA in concert with a nonbinding mutant of sCMG2 (D50A) showed anti-PA antibody responses similar to those observed with PA alone. Our results suggest that addition of sCMG2 to a PA vaccine formulation is likely to result in a significantly diminished immune response, but we discuss the multitude of factors that could contribute to reduced immunogenicity.
KW - Anthrax
KW - Antigen processing
KW - Immunization
KW - Protein stability
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U2 - 10.1128/mSphere.0556-1955619
DO - 10.1128/mSphere.0556-1955619
M3 - Article
C2 - 31941807
AN - SCOPUS:85077940853
SN - 2379-5042
VL - 5
JO - mSphere
JF - mSphere
IS - 1
M1 - e00556
ER -